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PHYSICS (554 journals)            First | 1 2 3 4 5 6 | Last

Optical Communications and Networking, IEEE/OSA Journal of     Hybrid Journal   (Followers: 4)
Optofluidics, Microfluidics and Nanofluidics     Open Access  
Organic Electronics     Hybrid Journal   (Followers: 3)
Organic Photonics and Photovoltaics     Open Access   (Followers: 2)
PAJ: A Journal of Performance and Art     Hybrid Journal   (Followers: 11)
Particle Physics Insights     Open Access   (Followers: 2)
Particuology     Hybrid Journal  
Pattern Recognition in Physics     Open Access   (Followers: 1)
Pergamon Materials Series     Full-text available via subscription  
Phase Transitions and Critical Phenomena     Full-text available via subscription   (Followers: 1)
Philosophical Magazine     Hybrid Journal   (Followers: 2)
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences     Full-text available via subscription   (Followers: 5)
Philosophy and Foundations of Physics     Full-text available via subscription  
Physica B: Condensed Matter     Hybrid Journal   (Followers: 5)
physica status solidi (a)     Hybrid Journal   (Followers: 1)
physica status solidi (b)     Hybrid Journal   (Followers: 1)
physica status solidi (c)     Hybrid Journal   (Followers: 1)
Physica Status Solidi - Rapid Research Letters     Hybrid Journal   (Followers: 1)
Physical Communication     Hybrid Journal  
Physical Review C     Full-text available via subscription   (Followers: 18)
Physical Review Special Topics - Physics Education Research     Open Access   (Followers: 6)
Physical Review X     Open Access   (Followers: 5)
Physical Sciences Data     Full-text available via subscription   (Followers: 1)
Physics - spotlighting exceptional research     Full-text available via subscription   (Followers: 1)
Physics and Chemistry of Glasses - European Journal of Glass Science and Technology Part B     Full-text available via subscription   (Followers: 2)
Physics and Chemistry of Liquids: An International Journal     Hybrid Journal   (Followers: 2)
Physics and Chemistry of the Earth, Parts A/B/C     Hybrid Journal   (Followers: 3)
Physics and Materials Chemistry     Open Access  
Physics Essays     Full-text available via subscription  
Physics in Medicine & Biology     Full-text available via subscription   (Followers: 9)
Physics in Perspective     Hybrid Journal   (Followers: 1)
Physics International     Open Access   (Followers: 2)
Physics Letters A     Hybrid Journal   (Followers: 10)
Physics Letters B     Open Access   (Followers: 3)
Physics of Fluids     Hybrid Journal   (Followers: 24)
Physics of Life Reviews     Hybrid Journal   (Followers: 1)
Physics of Plasmas     Hybrid Journal   (Followers: 6)
Physics of the Dark Universe     Open Access  
Physics of the Solid State     Hybrid Journal   (Followers: 3)
Physics of Wave Phenomena     Hybrid Journal   (Followers: 1)
Physics Procedia     Partially Free   (Followers: 1)
Physics Reports     Full-text available via subscription   (Followers: 2)
Physics Research International     Open Access   (Followers: 1)
Physics Today     Hybrid Journal   (Followers: 20)
Physics World     Full-text available via subscription   (Followers: 3)
Physics-Uspekhi     Full-text available via subscription  
Physik in unserer Zeit     Hybrid Journal  
Physik Journal     Hybrid Journal  
Plasma Physics Reports     Hybrid Journal   (Followers: 2)
Pramana     Open Access   (Followers: 9)
Preview     Hybrid Journal  
Proceedings of the National Academy of Sciences     Full-text available via subscription   (Followers: 502)
Proceedings of the National Academy of Sciences, India Section A     Hybrid Journal   (Followers: 3)
Progress in Materials Science     Hybrid Journal   (Followers: 19)
Progress in Planning     Hybrid Journal   (Followers: 1)
Progress of Theoretical and Experimental Physics     Open Access  
Quantum Electronics     Full-text available via subscription   (Followers: 2)
Quantum Measurements and Quantum Metrology     Open Access  
Quarterly Journal of Mechanics and Applied Mathematics     Hybrid Journal   (Followers: 3)
Radiation Effects and Defects in Solids     Hybrid Journal   (Followers: 1)
Radiation Measurements     Hybrid Journal   (Followers: 2)
Radiation Physics and Chemistry     Hybrid Journal   (Followers: 1)
Radiation Protection Dosimetry     Hybrid Journal   (Followers: 2)
Radiation Research     Full-text available via subscription   (Followers: 3)
Radio Science     Full-text available via subscription   (Followers: 3)
Radiological Physics and Technology     Hybrid Journal   (Followers: 1)
Reflets de la physique     Full-text available via subscription  
Reports on Mathematical Physics     Full-text available via subscription  
Reports on Progress in Physics     Full-text available via subscription   (Followers: 2)
Research & Reviews : Journal of Physics     Full-text available via subscription  
Research in Drama Education     Hybrid Journal   (Followers: 11)
Research Journal of Physics     Open Access  
Results in Physics     Open Access   (Followers: 1)
Reviews in Mathematical Physics     Hybrid Journal  
Reviews of Accelerator Science and Technology     Hybrid Journal  
Reviews of Geophysics     Full-text available via subscription   (Followers: 19)
Reviews of Modern Physics     Full-text available via subscription   (Followers: 17)
Revista Colombiana de Física     Open Access  
Revista Mexicana de Astronomía y Astrofísica     Open Access  
Revista Mexicana de Física     Open Access  
Revista mexicana de física E     Open Access  
Rheologica Acta     Hybrid Journal   (Followers: 3)
Russian Journal of Mathematical Physics     Hybrid Journal  
Russian Journal of Nondestructive Testing     Hybrid Journal   (Followers: 1)
Russian Physics Journal     Hybrid Journal  
Samuel Beckett Today/Aujourd'hui     Full-text available via subscription   (Followers: 2)
Science and Technology of Nuclear Installations     Open Access   (Followers: 1)
Science China : Physics, Mechanics & Astronomy     Full-text available via subscription   (Followers: 1)
Science Foundation in China     Full-text available via subscription   (Followers: 2)
Scientific Journal of Physical Science     Open Access  
Scientific Reports     Open Access   (Followers: 11)
Selected Topics in Applied Earth Observations and Remote Sensing, IEEE Journal of     Hybrid Journal   (Followers: 16)
Sensor Letters     Full-text available via subscription   (Followers: 1)
Sensors and Actuators A: Physical     Hybrid Journal   (Followers: 34)
Services Computing, IEEE Transactions on     Hybrid Journal   (Followers: 3)
Shock and Vibration     Hybrid Journal   (Followers: 7)
Shock Waves     Hybrid Journal   (Followers: 4)
Small     Hybrid Journal   (Followers: 9)
Software Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 20)
Solid State Physics     Full-text available via subscription  

  First | 1 2 3 4 5 6 | Last

Journal Cover physica status solidi (c)     [SJR: 0.397]   [H-I: 27]
   [3 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1862-6351 - ISSN (Online) 1610-1642
   Published by John Wiley and Sons Homepage  [1605 journals]
  • Towards single‐trap spectroscopy: Generation‐recombination
           noise in UTBOX SOI nMOSFETs
    • Authors: Eddy Simoen; Bogdan Cretu, Wen Fang, Marc Aoulaiche, Jean‐Marc Routoure, Regis Carin, Sara dos Santos, Jun Luo, Chao Zhao, Joao Antonio Martino, Cor Claeys
      Pages: n/a - n/a
      Abstract: An overview is given on the possibilities of using generation‐recombination (GR) noise as a tool for defect spectroscopy in semiconductor materials and devices. The method is illustrated by n‐channel MOSFETs fabricated on silicon‐on‐insulator (SOI) substrates with an ultra‐thin buried oxide (UTBOX). As will be shown, the use of fully depleted (FD) UTBOX devices offers some unique opportunities and challenges. In the first instance, one can apply the standard GR noise spectroscopy in function of the temperature to derive the relevant deep‐level parameters like the activation energy, the capture cross section and the concentration. In addition, some new type of spectroscopy can be applied to defects in the silicon film by exploiting the front‐ and/or back‐gate bias dependence of the Lorentzian noise parameters. Finally, it is shown that for small geometry transistors the GR noise is generated by one or only a few centres. This becomes obvious in the time domain, where the channel current exhibits random telegraph signal (RTS) fluctuations. The up and down time constants and the relative RTS amplitude can be used to derive the GR centre parameters and, moreover, its spatial location, when combined with numerical device simulations. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-01-23T08:10:50.318829-05:
      DOI: 10.1002/pssc.201400075
  • Plasma‐assisted molecular beam epitaxy of strain‐compensated
           a‐plane InGaN/AlGaN superlattices
    • Authors: Ryan W. Enck; N. Woodward, C. Gallinat, G. Metcalfe, A. V. Sampath, H. Shen, M. Wraback
      Pages: n/a - n/a
      Abstract: Strain‐compensated InGaN/AlGaN structures can enable the growth of thick layers of InGaN epitaxial films far beyond the critical thickness for InGaN grown pseudomorphically to GaN. In this paper, we demonstrate the epitaxial growth of high‐quality strain‐compensated a‐plane In0.12Ga0.88N/Al0.19Ga0.81N superlattices up to 5 times thicker than the critical thickness on free‐standing a‐plane GaN substrates by plasma‐assisted molecular beam epitaxy (PA‐MBE). The superlattices consist of 50 to 200 periods of 10 nm thick In0.12Ga0.88N and 6 nm thick Al0.19Ga0.81N layers. The structures are characterized using a double crystal X‐ray diffractometer, asymmetric reciprocal space mapping, and atomic force microscopy. We use X‐ray diffraction to determine the strain, composition, degree of relaxation, and superlattice period of our samples. The structural characteristics of periodic structures containing from 50 to 200 periods are compared to single layer, uncompensated In0.12Ga0.88N films. A 100 period structure exhibited only 15% relaxation compared to 69% relaxation for the bulk In0.12Ga0.88N film grown with the same total InGaN thickness but without strain‐compensating layers. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-01-23T08:10:49.21007-05:0
      DOI: 10.1002/pssc.201400208
  • HVPE homoepitaxy on freestanding AlN substrate with trench pattern
    • Authors: Yoshinobu Watanabe; Hideto Miyake, Kazumasa Hiramatsu, Yosuke Iwasaki, Shunro Nagata
      Pages: n/a - n/a
      Abstract: Conditions on chemical surface treatment and thermal treatment of sublimation‐freestanding AlN substrates were investigated to remove damage layers on surfaces for high‐quality and crack‐free AlN films grown by hydride vapour phase epitaxy (HVPE). By wet etching, the residue on the surface was removed and the polishing scratches were reduced. Atomic steps were formed on the surface by the subsequent thermal treatment at 1450 °C for 10 min, and surface layer of 220 nm in thickness was removed, Homoepitaxial growth on freestanding AlN substrate with trench pattern was also performed. A crack‐free AlN film with atomic steps was obtained on the trench‐patterned bulk AlN substrate, and the emission at the band edge near 206.9 nm was dominant. The wavelength of luminescence from cross‐sectional and surface of the HVPE‐AlN layer was maintained. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-01-23T08:10:48.179394-05:
      DOI: 10.1002/pssc.201400202
  • Time‐resolved photoluminescence characterization of 2 eV band in AlN
    • Authors: Ivan A. Aleksandrov; Vladimir G. Mansurov, Victor F. Plyusnin, Konstantin S. Zhuravlev
      Pages: n/a - n/a
      Abstract: We report time‐resolved and temperature‐dependent photoluminescence investigations of 2 eV photoluminescence band in AlN with below bandgap excitation. Series of the samples grown by molecular beam epitaxy on sapphire substrates with varying growth conditions have been studied. Intensity of the 2 eV photoluminescence band has been found to increase with increasing III/V flux ratio. The 2 eV photoluminescence band has been described in one‐dimensional configuration coordinate model. A possible origin of this orange emission has been discussed. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-01-23T08:10:47.139747-05:
      DOI: 10.1002/pssc.201400175
  • Degradation of external quantum efficiency of AlGaN UV LEDs grown by
           hydride vapor phase epitaxy
    • Authors: Natalia Shmidt; Alexander Usikov, Eugenia Shabunina, Anton Chernyakov, Alexey Sakharov, Sergey Kurin, Andrei Antipov, Iosif Barash, Alexander Roenkov, Heikki Helava, Yuri Makarov
      Pages: n/a - n/a
      Abstract: A comparative study of the degradation of HVPE‐grown 360 nm AlGaN/GaN UV and commercially available InGaN/GaN blue LED chips was performed. The common feature of the degradation of these two types of LEDs was found to be the increase of the conductivity of shunt paths under current injection. The paths (shunts) are localized in the extended defects system (EDS). It is proposed that the conductivity increase is due to defect formation under multiphonon carriers recombination in a part of the EDS enriched by Ga or In atoms. This process is accompanied by a local overheating and migration of Ga or In atoms. To increase the lifetime of the AlGaN/GaN UV LEDs to more than 2000 h it is necessary to improve their nano‐structural and nanoscale AlGaN composition ordering. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-01-23T08:10:46.189625-05:
      DOI: 10.1002/pssc.201400172
  • Unusual phonon mode behaviour in zinc‐blende BN/GaN superlattices
    • Authors: Devki N. Talwar; Andrew F. Zhou, Tzuen‐Rong Yang
      Pages: n/a - n/a
      Abstract: Comprehensive calculations of the long‐wavelength optical phonons are reported for zinc‐blende BN films by exploiting a linear response theory to simulate far‐infrared reflectivity and transmission spectra at oblique incidence. A rigid‐ion‐model is used to study the lattice dynamics of the unconventional BN/GaN short‐period superlattices (SLs). Besides empathizing, the anisotropic mode behaviour of optical phonons, the study has offered evidence of acoustic‐mode anti‐crossing, mini‐gap formation, confinement, as well as BN‐like modes falling between the gap regions separating the optical phonons of the two bulk (BN, GaN) semiconductor materials. A bond‐polarizability approach within the second‐nearest‐neighbour linear‐chain model is also employed to visualize the Raman intensity profiles of the short‐period BN/GaN SLs, revealing major trends of the phonon characteristics noted in many conventional SLs, while eliciting some interesting contrasts. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-01-23T08:10:45.055269-05:
      DOI: 10.1002/pssc.201400157
  • Accurate measurement of atomic segregation to grain boundaries or to
           planar faults by analytical transmission electron microscopy
    • Authors: Thomas Walther
      Pages: n/a - n/a
      Abstract: A method of analytical transmission electron microscopy is described that has been successfully applied to study dopant segregation to inversion domain boundaries in zinc oxide, to quantify the thicknesses of sub‐nanometre thin epitaxial layers grown by molecular beam epitaxy of indium arsenide (InAs) on gallium arsenide (GaAs) or silicon/germanium on silicon and proved the absence of any gettering of As or Ga dopants at Sigma=3 {111} grain boundaries in silicon, with a precision of
      PubDate: 2015-01-23T08:10:43.66336-05:0
      DOI: 10.1002/pssc.201400121
  • Characterization of TiO2 antireflection coatings elaborated by APCVD for
           monocrystalline silicon solar cells
    • Authors: D. Hocine; M. S. Belkaid, M. Pasquinelli, L. Escoubas, P. Torchio, A. Moreau
      Pages: n/a - n/a
      Abstract: In this work, high quality titanium dioxide thin films were grown by an efficient, less expensive and rapid method of Atmospheric Pressure Chemical Vapor Deposition (APCVD) from TiCl4 precursor for application as antireflection coatings on monocrystalline silicon solar cells with the aim to reduce the front surface reflection losses. The microstructural, electrical and optical properties of the produced coatings were successfully characterized by Atomic Force Microscopy (AFM), Four Point Probe (FPP) and Spectroscopic Ellipsometry (SE). The produced coatings were uniform, homogenous and relatively smooth. The density of the deposited TiO2 films is found to be ρ ′ = 3.11 g/cm3. The porosity of these films is estimated to ϕ = 24 %. A perfect agreement between the AFM results and the ellipsometric results was confirmed. The refractive index of our TiO2 thin films was found to be n = 2.25 at the wavelength λ = 550 nm, with a thickness of 56.2 nm. Our results show the possibility to fabricate TiO2 layers with the optimal optical qualities required for antireflection coating, using the APCVD technique. An excellent agreement is reached between our experimental results and calculated results for TiO2 single‐layer antireflection coating on monocrystalline silicon solar cells. The electrical resistivity of the deposited TiO2 films at 450°C annealed at 450°C for 1 hr, was found to be ρ = 1.7 × 10‐3 Ω.cm. The sheet resistance of our TiO2 films was equal to R□ = 303 Ω/□. The obtained results demonstrate the real opportunity of the APCVD technique to prepare high quality antireflection coatings for high efficiency silicon solar cells. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-01-23T08:10:42.468015-05:
      DOI: 10.1002/pssc.201400085
  • Reflectance analysis on the MOCVD growth of AlN on Si(111) by the virtual
           interface model
    • Authors: Tuoh‐Bin Ng; David A. Ewoldt, Debra A. Shepherd, Mark J. Loboda
      Pages: n/a - n/a
      Abstract: The reflectance‐time profile of AlN‐on‐Si(111) growth by MOCVD as acquired through an in‐situ optical reflectance monitor is analyzed. It is found that, similar to the case of GaN‐on‐sapphire nucleation and growth through the low temperature GaN or AlN buffer layer techniques, the reflectance profile for AlN‐on‐Si also contains information that relate to the growth mechanism, which can then be correlated to the as‐grown material quality. Based on the equations for the Virtual Interface model, a set of 6 parameters can be used to curve‐fit the reflectance traces of AlN growth as acquired by the in‐situ optical monitor. By analyzing a range of 405 nm AlN reflectance‐time data from single layer AlN growth to multilayer AlN/AlGaN/GaN stack grown on Si(111), the “goodness of fit” statistics are found to correlate with material quality metrics such as the XRD (002) rocking curve FWHM for AlN, microscopic morphological roughness of the AlN surface, as well as the resultant wafer bow and curvature for GaN/AlGaN grown on the AlN/Si(111) substrate. The correlations provide useful insight into the desirable mechanism and growth mode for the high temperature MOCVD growth of AlN and GaN on Si(111). When fully established, the technique has the potential of being used as an in‐situ pass/fail screen for the MOCVD growth of GaN‐on‐Si. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-01-23T08:10:41.27289-05:0
      DOI: 10.1002/pssc.201400159
  • Hybrid ZnO:polystyrene nanocomposite for all‐polymer photonic
    • Authors: Paola Lova; Giovanni Manfredi, Luca Boarino, Michele Laus, Giulia Urbinati, Tonia Losco, Franco Marabelli, Valentina Caratto, Maurizio Ferretti, Maila Castellano, Cesare Soci, Davide Comoretto
      Pages: n/a - n/a
      Abstract: We report on ZnO nanoparticles‐polystyrene (PS) nanocomposites (NC) engineered to modify PS matrix permeability and refractive index (n), and to fabricate 1D all‐polymer photonic crystals (PC) for sensing applications. The new NC can be easily processed from solutions to prepare high quality thin films by spin coating. ZnO nanoparticles (n = 1.98) have been synthetized by solvothermal route and grafted with a silane to reduce phase segregation in the PS matrix (n = 1.58). Such procedure led to an increase of the matrix refractive index of about 1%. By casting alternated layers of the NC and cellulose acetate (CA, n = 1.46), we fabricated free‐standing and flexible distributed Bragg reflectors (DBRs) of excellent optical quality. Preliminary results on the use of such DBRs as solvent vapor sensors are reported. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-11-26T06:30:11.689709-05:
      DOI: 10.1002/pssc.201400209
  • Influence of doping on the optical properties of silicon nanocrystals
           embedded in SiO2
    • Authors: Mathieu Frégnaux; Rim Khelifi, Yann Le Gall, Dominique Muller, Daniel Mathiot
      Pages: n/a - n/a
      Abstract: Co‐implantation, with overlapping implantation projected ranges, of Si and doping species (P, As, B) followed by a thermal annealing step is a viable route to form doped Si nanocrystals (NCs) embedded in SiO2. This presentation deals with optical characterizations of both doped and undoped Si‐NC prepared by this method. The NC effective presence in the oxide layer and their crystallinity is verified by Raman spectrometry. Photoluminescence (PL) and PL excitation measurements reveal quantum confinement effects and a gradual PL quenching with increasing dopant concentrations. The measured Stokes shift remains constant and its value ∼ 0.2 eV is almost twice the Si–O vibration energy. This suggests that a possible radiative recombination path is a fundamental transition assisted by a local phonon. Lifetime investigations show that PL time‐decays follow a stretched exponential. Atomic probe tomography analyses demonstrate that n‐type dopants (P, As) are efficiently introduced in the NC core, whereas p‐type dopant (B) are located at the NC/SiO2 interface. All together these experimental observations question on possible different carrier recombination paths in P or As doped NC compared to B one's. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-11-26T06:30:10.354883-05:
      DOI: 10.1002/pssc.201400079
  • Localization of dislocation‐related luminescence centers in
           self‐ion implanted silicon and effect of additional boron ion doping
    • Authors: D. I. Tetelbaum; A. N. Mikhaylov, A. I. Belov, D. S. Korolev, A. N. Shushunov, A. I. Bobrov, D. A. Pavlov, E. I. Shek, N. A. Sobolev
      Pages: n/a - n/a
      Abstract: The depth distribution of light‐emitting centers of the D1 dislocation‐related photoluminescence line (∼ 1.5 μm) in silicon implanted with Si+ ions and annealed at 1100 °C in the oxidizing chlorine‐containing atmosphere has been investigated by means of the layer‐by‐layer chemical etching. It is established with the application of cross‐sectional transmission electron microscopy that the main contribution to the D1 line is made by the centers located at the depths of up to ∼ 150 nm, i.e. in the region of Si+ ion ranges, whereas the dislocations produced by Si+ implantation and annealing at 1100 °C penetrate to the depth of ∼ 1000 nm. Additional boron ion doping with subsequent annealing at 800 °C in N2 atmosphere improves the emission in comparison with the undoped but annealed reference sample, however the additional annealing at 800 °C per se results in the photoluminescence weakening. The dependence of the D1 line intensity on boron ion dose is found to be nonmonotonous. The interpretation of the obtained results is given in relation to the key role of selfinterstitials and boron impurity in the formation of radiative and nonradiative centers. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-11-26T06:30:09.233848-05:
      DOI: 10.1002/pssc.201400099
  • Cover Picture: Phys. Status Solidi C 11–12/2014
    • Pages: n/a - n/a
      Abstract: In their article “Temperature dependent switching behaviour of nickel silicided undoped silicon nanowire devices“ (see pp. 1611–1617), Beister et al. investigate the Schottky barriers in back‐gated, single crystalline, undoped silicon nanowire field‐effect transistors with Ni‐silicided source/drain contacts. These devices exhibit an ambipolar behaviour, which gives the opportunity to measure both electron and hole transport on a single nanowire. For the purpose of barrier height extraction, the temperature dependence of the elec‐trical switching properties is analysed in detail. A simple, phenomenological model illustrates the leading order temperature dependence of the source–drain current, which originates predominantly from charge carrier injection by tunnel‐ ling through the first Schottky junction. Drain current versus gate voltage measurements have been performed for various temperatures between 280 K and 360 K and for several drain voltages on a single nanowire device. The temperature dependence of the source–drain current for specific gate and drain voltages is evaluated within the framework of voltage dependent effective barrier heights. As a result, the temperature dependence of the tunnelling current is not only important for the sub‐threshold region, but also plays a significant role in the transistor “on‐state”. In addition, the effective barrier heights for electrons and holes tend towards the natural Schottky barriers of the NiSi2–Si interface, if the applied external fields generate the case of flat band condition at the injection‐sided Schottky barrier, i.e. in the deep “off‐state” region.
      PubDate: 2014-11-21T10:35:44.910828-05:
      DOI: 10.1002/pssc.201470063
  • Issue Information: Phys. Status Solidi C 11–12/2014
    • Pages: n/a - n/a
      PubDate: 2014-11-21T10:35:42.155886-05:
      DOI: 10.1002/pssc.201470064
  • Bio‐organic memristive device: polyaniline–Physarum
           polycephalum interface
    • Authors: Angelica Cifarelli; Tatiana Berzina, Victor Erokhin
      Pages: n/a - n/a
      Abstract: Organic memristive device is an electronic system mimicking some properties of biological synapses. Slime mold – Physarum polycephalum – is a single cell living being, widely considered now for the unconventional computing application. This work is dedicated to the realization of hybrid organic memristive device/Physarum polycephalum system and studying of its electrical properties. It was found that the slime mold remains alive only when the appropriate biocompatible layer is inserted into the structure and that the characteristics of the system are very different from those of the standard organic memristive devices. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-11-20T06:40:13.603688-05:
      DOI: 10.1002/pssc.201400191
  • Resistive switching on MgO‐based metal‐insulator‐metal
           structures grown by molecular beam epitaxy
    • Authors: M. Menghini; C. Quinteros, C.‐Y Su, P. Homm, P. Levy, J. Kittl, J.‐P. Locquet
      Pages: n/a - n/a
      Abstract: We report on non‐polar switching of the resistance between a low and a high resistive state in MgO‐based metal‐insulator‐metal structures. The MgO films were grown by MBE on top of Pt/Si substrates and Pt electrodes were evaporated on top. The obtained resistance ratio is of the order of 108‐109, much larger than previously reported values in similar devices. We observe a gradual degradation during consecutive switching events and a significant large dispersion of the voltages at which the resistance switch occurs. The overall behavior of the devices is assigned to a low defect density in these samples. The obtained results suggest that the resistive switching is produced by the formation and disruption of Mg metallic filaments. In order to analyze the influence of interfaces, we also study the effect of adding an intermediate layer of either Al2O3 or Mg within the Pt/MgO/Pt structures. The switching performance appears to be enhanced when Al2O3 is used. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-11-20T06:40:12.408238-05:
      DOI: 10.1002/pssc.201400192
  • Defect‐enhanced F– ion conductivity in layer‐structured
           nanocrystalline BaSnF4 prepared by high‐energy ball milling combined
           with soft annealing
    • Authors: Florian Preishuber‐Pflügl; Viktor Epp, Suliman Nakhal, Martin Lerch, Martin Wilkening
      Pages: n/a - n/a
      Abstract: Fast ion conductors play one of the most important roles in solid state ionics as there is a great demand for their application in safe and powerful electrochemical energy storage systems. For such materials, it is known that the synthesis conditions may have significant impact on the final properties of the materials prepared. In this contribution, we made use of mechanosynthesis, carried out via high‐energy ball milling, to influence the ionic transport parameters of tetragonal, i.e., layer‐structured, BaSnF4. X‐ray powder diffraction (XRD) revealed that mechanical treatment of the binary fluorides BaF2 and SnF2 leads to a powder pointing to a nanocrystalline fluoride with (distorted) cubic symmetry. Differential scanning calorimetry (DSC) as well as preliminary in situ XRD measurements were used to follow the transformation towards the tetragonal modification with the composition BaSnF4. Broadband impedance spectroscopy was used to measure the overall electrical conductivity of the ternary fluoride. Remarkably, the layered form shows a room temperature conductivity of 7 × 10–4 S cm–1. Further emphasis was put on the characterization of the dielectric properties of the material, which was investigated by using different electrode materials to distinguish artefacts from intrinsic properties. Since we found a strong dependence of the real part of the permittivity on the electrode materials applied (carbon paste or sputtered Pt), we tend to assign the huge increase in permittivity, which was recently interpreted as giant dielectric constant, to interfacial polarization effects rather than to intrinsic properties. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-11-20T06:40:11.012985-05:
      DOI: 10.1002/pssc.201400193
  • Detection of nano‐structured particles with organic electrochemical
    • Authors: Agostino Romeo; Giuseppe Tarabella, Pasquale D'Angelo, Nicola Coppedè, Francesca Rossi, Roberto Mosca, Salvatore Iannotta
      Pages: n/a - n/a
      Abstract: Recently big efforts have been addressed to the development of techniques for sensing and characterization of nanoparticles (NPs), especially in aqueous environment, due to their possible harmfulness related to their nanometric size. In this work we describe a real time detection of NPs based on organic electrochemical transistors (OECTs). OECTs were employed to detect core‐shell super‐paramagnetic NPs (Fe3O4) functionalized with different polymeric coatings. The OECT response resulted to be a function of the density of NPs suspended in the solution, with sensitivity down to tens of µg/ml. The data, interpreted in terms of the effective gate voltage shift induced by the NPs, indicate that the sensing mechanism is correlated to the electrostatic interaction of NPs with the PEDOT:PSS transistor channel. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-11-20T06:40:09.841928-05:
      DOI: 10.1002/pssc.201400195
  • Employing threshold‐based behavior and network dynamics for the
           creation of memristive logic circuits and architectures
    • Authors: Ioannis Vourkas; Georgios Ch. Sirakoulis
      Pages: n/a - n/a
      Abstract: This work focuses on the creation of logic circuits by employing the collective dynamics of assembles of reciprocal memristors. A novel circuit design methodology is described where the computing systems comprise passive memristors interfaced with active CMOS circuitry, working under already known circuit design principles from the CMOS technology. The accuracy and completeness of this straightforward methodology is demonstrated through SPICE simulations which are based on a threshold‐type device model for memristors. Overall, this work contributes to the creation of proper methodologies which will enable the development of efficient design flows for circuits and architectures comprising memristors. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-11-20T06:30:16.949571-05:
      DOI: 10.1002/pssc.201400161
  • Numerical investigation of nanoscale SiGe DG MOSFET performance against
           the interfacial defects
    • Authors: Toufik Bentrcia; Fayçal Djeffal, Zouhir Dibi, Djemai Arar
      Pages: n/a - n/a
      Abstract: The SiGe‐based alloy is considered as one of the most promising materials for reliable and high performance microelectronic devices. The use of a lower band‐gap material in the channel region of the MOSFET, such as SiGe, is a potential candidate given their compatibility with the process developed for pure Si‐based devices. Moreover, the important increasing in the drain current due to the increased electrons mobility in SiGe material is expected. However, the growth of this material is not totally controlled, and the presence of defects is more than expected after a growth run of this material. Therefore, in order to obtain a global view of SiGe‐based nanoscale Double Gate (DG) MOSFET performance under critical conditions, numerical modeling of nanoscale SiGe DG MOSFET including Interfacial defect effects (SiGe/Si) is indispensable for the comprehension of the fundamentals of such device characteristics. Based on numerical investigation of a nanoscale SiGe DG MOSFET, including the defects in the interface region, in the present paper a numerical model for I‐V and small signal characteristics by including the interfacial defects, after considering the uniform function approximation for the interface defects distribution at the drain side, is developed to explain the immunity behavior of the nanoscale SiGe‐based transistor against the defect densities. In this context, DC and RF characteristics of the proposed design are analyzed by 2‐D numerical simulation and compared with conventional Si DG MOSFET characteristics. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-11-20T06:30:15.916208-05:
      DOI: 10.1002/pssc.201400088
  • Implementation of adaptive coupling through memristor
    • Authors: Mattia Frasca; Lucia Valentina Gambuzza, Arturo Buscarino, Luigi Fortuna
      Pages: n/a - n/a
      Abstract: Since its discovery, memristor attracted a lot of attention for its potential applications as next generation electronic device, as system for modeling and implementing biological synapses and as key component in nonlinear circuits. Here we exploit the peculiarities of the HP memristor in order to realize an adaptive coupling, able to reach consensus and synchronization between two dynamical systems. In particular, the coupling scheme consists of two HP memristors connected in antiparallel which allow to deal with consensus/synchronization error of either positive and negative sign. Simulation results on consensus of two agents with integrator dynamics and synchronization of two Chua's circuits show the suitability of the proposed approach. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-11-20T06:30:15.067691-05:
      DOI: 10.1002/pssc.201400097
  • Memristors under the influence of noise and temperature
    • Authors: G. A. Patterson; F. Sangiuliano Jimka, P. I. Fierens, D. F. Grosz
      Pages: n/a - n/a
      Abstract: We study the performance of a manganite sample meant for memresistive applications. In particular, we experimentally address the interplay between temperature and electrical noise the sample is subject to. Results reveal an optimum noise amplitude that maximizes the contrast between low‐ and high‐resistive states, and a decaying contrast with increasing temperature. We introduce a numerical model accounting for the observed experimental behavior. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-11-20T06:30:14.041592-05:
      DOI: 10.1002/pssc.201400125
  • Comparative study of defect evolution in carbon implanted strained SiGe
           and SiSn layers
    • Authors: Peter I. Gaiduk; John Lundsgaard Hansen, Arne Nylandsted Larsen, Wolfgang Skorupa
      Pages: n/a - n/a
      Abstract: By combining secondary ion‐mass spectrometry, transmission‐electron microscopy (TEM) and Rutherford‐backscattering spectrometry we show that the redistribution of implanted carbon atoms around epitaxially strained Si/SiGe layers results in their accumulation on the Si side and depletion on the SiGe side. On the contrary, uphill diffusion of carbon into SiSn layers takes place in the case of Si/SiSn structures. The TEM study demonstrates formation of dislocation loops, stacking faults and interstitial clusters in the Si/SiGe layers, but elimination of interstitial dislocation loops and suppression of tin precipitates in the Si/SiSn layers. We deduced different evolution of dislocation loops and a precipitate is due to dopant‐defect complexes. The complex formation is enhanced by separation of implanted point defects in strain‐fields of Si/SiSn and Si/SiGe layers. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-11-20T06:30:12.913759-05:
      DOI: 10.1002/pssc.201400135
  • Formation of nanodimensional structures on surfaces of GaAs and Si by
           means of ion implantation
    • Authors: S. B. Donaev; F. Djurabekova, D. A. Tashmukhamedova, B. E. Umirzakov
      Pages: n/a - n/a
      Abstract: We obtained the two‐ and three‐component nanostructures by means of ion implantation of low‐energy Co and Ba ions in the surface layers of Si and GaAs in combination with the post‐implantation annealing. We show that flat shaped nanocrystals (nanoislands) of two‐ and three‐component composition, Co‐Si and Ga‐Ba‐As, start forming at ion fluences of Φ = (6¸8)×1014 cm‐2. After the laser annealing and short time electron heating we observed the formation of CoSi2 and Ga0.4Ba0.6As nanocrystals. Our results show that the size effects are clearly seen in electronic properties (opening of the band gap) when the lateral size of nanocrystals is less than 15‐30 nm, or in case of solid nanofilms, similar effect is observed at the thickness less than 3‐4 nm. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-11-20T06:30:11.72748-05:0
      DOI: 10.1002/pssc.201400156
  • Memristive sorting networks
    • Authors: Milan Frátrik; Martin Klimo, Ondrej Šuch, Ondrej Škvarek
      Pages: n/a - n/a
      Abstract: Resistive switching in thin‐film solid state devices is a rapidly progressing research area. Several new devices and applications, based on resistive switching, were proposed. The devices fall into realm of unconventional computing. In this paper we present memristor implementation of fuzzy logic. We describe fuzzy logic operations, simulation method used in our experiments and finally we compare two sorting algorithms implemented in memristive network. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-11-20T06:30:10.00131-05:0
      DOI: 10.1002/pssc.201100000
  • Charged defects and defect‐induced processes in nitrogen films
    • Authors: Elena Savchenko; Ivan Khyzhniy, Sergey Uyutnov, Andrey Barabashov, Galina Gumenchuk, Alexey Ponomaryov, Vladimir Bondybey
      Pages: n/a - n/a
      Abstract: Radiation effects in solid nitrogen irradiated with an electron beam were studied with emphasis on the role of charged centers in radiation‐induced phenomena. The experiments were performed employing luminescence method and activation spectroscopy techniques – spectrally resolved thermally stimulated luminescence TSL and thermally stimulated exoelectron emission. Samples were probed in depth by varying electron energy, thus discriminating radiation‐induced processes in the bulk and at the surface. Spectroscopic evidence of the excited N2* (C3Πu) molecule desorption was obtained for the first time and mechanism of the phenomenon based on recombination of electron with intrinsic charged center N4+ was proposed. The key role of N3+ center dissociative recombination in generation of N radicals is suggested. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-11-20T06:30:08.845066-05:
      DOI: 10.1002/pssc.201400166
  • Error control on spectral data of four‐wave mixing based on
           a‐SiC technology
    • Authors: M. A. Vieira; M. Vieira, V. Silva, P. Louro, M. Barata
      Pages: n/a - n/a
      Abstract: In this paper we exploit the nonlinear property of the SiC multilayer devices to design an optical processor for error detection that enables reliable delivery of spectral data of four‐wave mixing over unreliable communication channels. The SiC optical processor is realized by using double pin/pin a‐SiC:H photodetector with front and back biased optical gating elements. Visible pulsed signals are transmitted together at different bit sequences. The combined optical signal is analyzed. Data show that the background acts as selector that picks one or more states by splitting portions of the input multi optical signals across the front and back photodiodes. Boolean operations such as EXOR and three bit addition are demonstrated optically, showing that when one or all of the inputs are present, the system will behave as an XOR gate representing the SUM. When two or three inputs are on, the system acts as AND gate indicating the present of the CARRY bit. Additional parity logic operations are performed using four incoming pulsed communication channels that are transmitted and checked for errors together. As a simple example of this approach, we describe an all‐optical processor for error detection and then provide an experimental demonstration of this idea. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-11-20T06:23:40.372568-05:
      DOI: 10.1002/pssc.201400067
  • Unconventional digital computing approach: memristive nanodevice platform
    • Authors: Mahyar Shahsavari; M. Faisal Nadeem, S. Arash Ostadzadeh, Philippe Devienne, Pierre Boulet
      Pages: n/a - n/a
      Abstract: Memristor is a two‐terminal nanodevice that has recently attracted the attention of many researchers. Its simple structure, non‐volatility behavior, high‐density integration, and low‐power consumption make the memristor a promising candidate to act as a switch in digital gates for future high‐performance and low‐power nanocomputing applications. In this paper, we model the behavior of memristor by using Verilog‐A. To investigate its characteristics in a circuit, we use the HSPICE simulator. Furthermore, a library of digital gates are provided by using two approaches to make digital gates: the first one is based on material implication (IMP) and the second one is based on crossbar arrays. Finally, we perform a comparison and evaluation between the two methods. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-11-20T06:23:39.214285-05:
      DOI: 10.1002/pssc.201400069
  • Band alignment and effective work function of atomic‐layer deposited
           VO2 and V2O5 films on SiO2 and Al2O3
    • Authors: F. Cerbu; H.‐S. Chou, I. P. Radu, K. Martens, A. P. Peter, V. V. Afanas'ev, A. Stesmans
      Pages: n/a - n/a
      Abstract: The effective work function (EWF) and the energy position of the valence band in 20‐40‐nm thick VO2and V2O5layers grown by atomic layer deposition (ALD) on top of insulating SiO2 and γ‐Al2O3 films were evaluated using the comparison between capacitance‐voltage and internal photoemission measurements. From the capacitance measured at different temperatures on the metal‐VO2(V2O5)‐insulator‐silicon and metal‐insulator‐silicon diodes we found that the both studied vanadium oxides have the same EWF as gold electrodes evaporated on the same oxides. This result is further collaborated by the internal photoemission experiments at the VO2/SiO2 and V2O5/SiO2 interfaces which indicate the energy barrier between the top of the vanadium oxide valence band (in the insulating phase) and the insulator conduction band to be 4.1 ± 0.1 eV. Since the transition from the narrow‐gap VO2 to the wide‐gap V2O5 oxide causes no change in the WF or in the photoemission threshold, we conclude that the ALD‐grown VO2 in its insulating phase represents a a heavily‐doped semiconductor which becomes metallic upon metal‐insulator transition without significant EWF change. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-11-20T06:23:32.486562-05:
      DOI: 10.1002/pssc.201400037
  • Conductivity patterning with Physarum polycephalum: natural growth and
    • Authors: Alice Dimonte; Tatiana Berzina, Angelica Cifarelli, Valentina Chiesi, Franca Albertini, Victor Erokhin
      Pages: n/a - n/a
      Abstract: The present work is dedicated to the use of Physarum polycephalum slime mold, an unicellular organism self‐adapting, self‐repairing and self‐repellent, for the realization of elements for unconventional computational systems. Physarum continuously changes its shape under the influence of different stimuli like attractors (food in the most of cases) and repellents (light, temperature, humidity, chemicals), creating optimized networks. Here we introduced a new, softer, element able to influence the motion and the shape of Physarum: the DEFLECTOR. Physarum polycephalum, loaded with magnetic particles and placed under a magnetic field, is conditioned in its active zones routing and shape topology networks. Thus, slime mold can be used as particles carrier and, moreover, it is possible to deflect the mold movement and realize chemical composites in defined places what allows to consider Physarum as a simple version of bio‐robot. On the other hand, we have realized the idea of creating networks with the varied conductivity with the slime mold on polyaniline (PANI) substrates. As the result, it was shown that Physarum growth results in the changing of the conductivity state of PANI layers in different ways, providing negative and positive patterning of the sample. The possibility to control mold's direction with a deflector together with the capability of Physarum to pattern PANI surfaces are the main points of this work. This paper opens new possibilities of the development in many fields and areas from the electrical circuit design and the bio‐actuators (bio‐) robot research, up to the unconventional computing and realization of a novel category of polymer‐mold‐modified. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-11-19T08:10:25.729133-05:
      DOI: 10.1002/pssc.201400077
  • Nanoengineered polymeric capsules as elements of unconventional computing
    • Authors: Svetlana Erokhina; Laura Pastorino
      Pages: n/a - n/a
      Abstract: Nanoengineered polymeric capsules are smart objects with a shell of 4‐20 nm thick and a core volume, that can be filled with the different substances. The capsules can be delivered to a desirable place and the encapsulated material release can be triggered by the variation of the environmental medium parameters or by the external action. In this paper, we present important steps of the capsule preparation and discuss how they can be used in the field of chemical and bio‐chemical unconventional computer systems. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-11-19T08:10:24.536825-05:
      DOI: 10.1002/pssc.201400074
  • Microscopic and spectroscopic analysis of the nature of conductivity
           changes during resistive switching in silicon‐rich silicon oxide
    • Authors: Mark Buckwell; Luca Montesi, Adnan Mehonic, Omer Reza, Leon Garnett, Manveer Munde, Stephen Hudziak, Anthony J. Kenyon
      Pages: n/a - n/a
      Abstract: Redox‐based resistive random access memory (RRAM) has the scope to greatly improve upon current methods of data storage, despite incomplete understandings of material switching mechanisms. We make use of atomic force microscopy (AFM), conductive atomic force microscopy (cAFM) and X‐ray photoelectron spectroscopy (XPS) to characterise the physical processes occurring in the changes in conductance state in silicon‐rich silicon oxide RRAM. Surface analyses of the insulating oxide layer of our devices are employed to establish the chemical and structural properties of pristine and switched states. The removal of oxygen from the active layer is observed to be concomitant with the appearance of varying degrees of surface distortion and regions of high conductivity in an otherwise‐insulating material. These results support the currently‐recognised model of a resistive switching mechanism that is reliant upon the migration of oxygen ions under an electrical bias. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-11-19T07:40:25.645425-05:
      DOI: 10.1002/pssc.201400160
  • Formation and properties of SiC and C particle nano‐colloids in
           non‐polar liquids
    • Authors: Hamza Hajjaji; Yuriy Zakharko, Sergeï Alekseev, Gérard Guillot, David Philippon, Philippe Vergne, Jean‐Marie Bluet
      Pages: n/a - n/a
      Abstract: Electrochemical etching of polycrystalline SiC is used in order to form SiC nanoparticles. During the process, both SiC and carbon‐related nanoparticles like onion like carbon are formed. The two different species can be selected by centrifugation. Both nanoparticles have been functionalized for dispersion in non‐polar liquids. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-11-19T07:40:24.383773-05:
      DOI: 10.1002/pssc.201400210
  • Perspectives of enhancement of p‐type conductivity in ZnO nanowires
    • Authors: Tamar Tchelidze; Tamaz Kereselidze, Teimuraz Nadareishvili
      Pages: n/a - n/a
      Abstract: Semiconductor nanowires are believed to act as key elements in future nanoscaled optoelectronic devices, as they offer intriguing electrical and optoelectronic properties. However, the future of any semiconductor nanowire technology will essentially rely on their doping capability. The availability of both n‐ and p‐type semiconductors is important for the realization of nanowire‐based electronics. Wide band gap semiconductors, such as ZnO, suffer from doping polarity. They can be easily doped n‐ (or p‐type) to the expense of difficulties for doping of opposite type. Space confinement changes donor and acceptor ionization energies. The main factor that makes difficult to obtain n‐ or p‐conductivity is the formation of compensating defects. Compensating processes are strongly affected by electronic structure of the system: band gap, ionization energies of donors, acceptors and their compensation centers. In the presented work we calculated energy levels of an electron bound to Coulomb impurity that is incorporated in semiconductor nanowire. Effect of dielectric confinement on ionization energies are considered as well. For analyzing perspectives of suppressing processes of compensation and achieving low ohmic p‐conductivity Kröger method of quasi‐chemical equations is used. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-11-19T07:40:23.506535-05:
      DOI: 10.1002/pssc.201400150
  • Crystalline structure and optical properties of GaS‐CdS
    • Authors: Iuliana Caraman; Elmira Vatavu, Liviu Leontie, Marius Stamate, Dumitru Untila
      Pages: n/a - n/a
      Abstract: The GaS‐CdS composite has been obtained by intercalation of Cd in GaS single crystalline plates. The XRD analysis show that peaks determined by CdS and CdGa2S4 are found along with GaS characteristic reflection in intercalated samples. The spectral dependence of absorption coefficient for the GaS‐CdS composite is determined by both absorption mechanisms in GaS and in CdS components for α > 103 cm–1. The photoluminescence spectrum (78 K) of the composite consists of radiative recombination bands characteristic for both CdS and GaS. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-11-19T07:40:22.527132-05:
      DOI: 10.1002/pssc.201400146
  • Ion current rectification effect of porous graphene membrane
    • Authors: Jian Zeng; Huijun Yao, Dan Mo, Jinglai Duan, Jiande Liu, Dianliang Cao, Pengfei Zhai, Jie Liu, Youmei Sun
      Pages: n/a - n/a
      Abstract: Graphene, as an important ideal two‐dimensional material, is driving more and more attention because of its unique mechanical strength and chemical stability. In this work, the rectification effect of nanopores in graphene/PET structure at different KCl concentration is investigated. Porous graphene membrane is obtained by using heavy ion irradiation technology. During investigating the ion current rectification effect, PET membrane with conical pores acts as porous graphene's substrate. The rectification coefficient of nanopores in graphene/PET is deduced from the current‐voltage curves at KCl solution with different concentrations. The porous graphene/PET shows a relative higher rectification ratio and is more resistive to pH value while comparing the nanopores in PET. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-11-19T07:40:21.71662-05:0
      DOI: 10.1002/pssc.201400144
  • X‐ray photoelectron spectroscopy of gold nanowire arrays embodied in
           ion‐track template
    • Authors: Huijun Yao; Lu Xie, Jinglai Duan, Dan Mo, Yonghui Chen, Shuangbao Lv, Jie Liu, Youmei Sun
      Pages: n/a - n/a
      Abstract: The gold nanowire arrays with different diameter and length were successfully prepared in etched ion‐track template assisted with electrochemical deposition method and the nanowire's crystal structure and morphology were characterized by transmission electron spectroscopy (TEM) and scanning electron spectroscopy (SEM). The X‐ray photoelectron spectroscopy (XPS) was used to analyse the electronic states of gold nanowire arrays embodied in the template. It was found that the 4f core level binding energy of gold nanowire shifted toward higher binding energy when comparing with bulk gold. The positive binding energy shift increased significantly with decreasing nanowire's length or diameter. The enhanced final‐state effect was considered to explain the 4f binding energy shift of gold nanowire arrays embodied in template finally. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-11-19T07:40:20.556391-05:
      DOI: 10.1002/pssc.201400134
  • Effect of TiOx/TiO2 layer thickness on the properties of the pulsed laser
           deposited memristive device
    • Authors: G. I. Tselikov; A. V. Emelyanov, I. M. Antropov, V. A. Demin, P. K. Kashkarov
      Pages: n/a - n/a
      Abstract: Memristive properties of the pulsed laser deposited Pt/TiOx/TiO2/Pt heterostructures with different layer thicknesses are studied. It was found that the memristor device provides nonmonotonic dependence of the ratio of its resistance in low and high conductive states Roff/Ron on layers thickness. The maximum value of the ratio Roff/Ron = 200 is obtained when the thickness of both TiOx and TiO2 layers is 30 nm. The dependence of the stoichiometry index of deposited layers from their thicknesses is studied by means of Auger spectroscopy measurements. The nonmonotonic behaviour of the ratio Roff/Ron on layer thickness is discussed in terms of wide stoichiometry distribution through the amorphous TiOx/TiO2 structure. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-11-19T07:40:19.341634-05:
      DOI: 10.1002/pssc.201400123
  • Features of titanium oxide memristor fabrication by pulsed laser
    • Authors: Natalia Maslova; Yulia Khrapovitskaya, Ivan Sokolov, Yulia Grishchenko, Dmitry Mamichev, Maxim Zanaveskin
      Pages: n/a - n/a
      Abstract: The structural and electrophysical properties of titanium oxide based memristor obtained by pulsed laser deposition were analysed. The experimental results found the possibility of fine tuning of memristor active layers stoichiometry during deposition. In addition, the atomic force microscopy analysis of the surface of titanium oxide films revealed its high morphological homogeneity and continuity. The obtained memristors with gold contacts have been possessed bipolar switching mechanism and high endurance. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-11-19T07:40:18.480223-05:
      DOI: 10.1002/pssc.201400110
  • The titanium oxide memristor contact material's influence on element's
           cyclic stability to degradation
    • Authors: Yulia Khrapovitskaya; Natalia Maslova, Ivan Sokolov, Yulia Grishchenko, Dmitry Mamichev, Maxim Zanaveskin
      Pages: n/a - n/a
      Abstract: The effect of contact material on cyclic degradation stability of titanium oxide based memristor has been investigated. The memristors were made by pulsed laser deposition which has several advantages in comparison with other methods of memristor fabrication. The use of gold instead of platinum as a contact allows significantly the increase in memristor endurance. The results obtained are interpreted with a lower oxygen diffusion by gold contact compared to platinum which retains the properties of memristor functional layers. The titanium oxide memristor with high stability to cyclic resistive switching (up to 3000 cycles) has been obtained. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-11-19T07:40:17.503183-05:
      DOI: 10.1002/pssc.201400109
  • Morphologic, structural, and optical characterization of sol‐gel
           derived TiO2 thin films for memristive devices
    • Authors: Valentina Prusakova; Cristina Armellini, Alessandro Carpentiero, Andrea Chiappini, Cristian Collini, Sandra Dirè, Maurizio Ferrari, Leandro Lorenzelli, Marco Nardello, Simone Normani, Alessandro Vaccari, Alessandro Chiasera
      Pages: n/a - n/a
      Abstract: Sol‐gel derived TiO2 thin films were prepared by spin‐ coating from an alcoholic solution of titanium isopropoxide. With the aim to develop titania layers suitable for memristive devices, the films were deposited onto test structures based on fused silica quartz substrates patterned with a Ti (5nm)/Pt (50nm) layer. The reported fabrication protocol is suitable for the development of a memristive device. Optical, structural, and morphological features of the samples were investigated with complementary techniques, such as scanning electron microscopy (SEM), prism coupling m‐line and micro‐Raman spectroscopy as well as transmittance and profilometry measurements. The quality of the surface of the obtained films was evaluated by SEM technique, and the morphology of samples deposited with different fabrication protocols was investigated. Additionally, a computer code for the refractive index and thickness estimation from the transmittance spectra was developed by unconstrained optimization procedure. The results of simulation were in good agreement with the experimental data obtained by m‐line measurements. Moreover, the porosity of a specific set of test unannealed films has been estimated. TiO2 films exhibit thickness of tens of nm, and micro‐Raman spectroscopy in conjunction with SEM indicate the presence of anatase phase after thermal annealing at 400 °C. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-11-19T07:40:16.314219-05:
      DOI: 10.1002/pssc.201400101
  • Preparation and characterization of doped and undoped nanoporous carbon
           for heavy metal removal from aqueous solution
    • Authors: Imed Ghiloufi; Lassaad El Mir
      Pages: n/a - n/a
      Abstract: Nanoporous composites based on pyrogallol and formaldehyde (PF) reached by metallic nickel nanoparticles have been prepared using sol‐gel method to obtain PF/Ni adsorbent materials. The obtained samples were subjected of heat treatment under inert atmosphere at different pyrolysis temperatures during two hours. The X‐ray diffraction analysis (XRD) shows that PF sample were composed by amorphous material while PF/Ni XRD spectra exhibited the presence of metal nickel characteristic lines. The transmission electron microscopy (TEM) images indicate that PF sample was formed by homogenous material, and metallic nickel nanoparticles sized around 30 nm were dispersed in the PF/Ni nanocomposite. These materials were used to study the effect of pyrolysis temperatures on the uptake of Cr, Ni, Cd and Co from aqueous solution. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-10-29T05:10:22.550571-05:
      DOI: 10.1002/pssc.201400017
  • Investigation of AlGaInP heterostructures under gamma‐irradiation in
           the field of restructuring defect structure
    • Authors: Alexander Gradoboev; Ksenia Orlova
      Pages: n/a - n/a
      Abstract: The given paper presents the results of studying the resistance of AlGaInP heterostructures with multiple quantum wells to 60Co gamma‐quantum irradiation. The research was completed for light emitting diodes (λ = 630 nm). The irradiation was completed under the passive powering mode without the imposition of the electric field while the level of exposure was characterized by the absorbed dose. It has been established that the emission power reduction has three stages. At the first stage the radiation power reduces due to radiation‐induced transformation of the initial structure defects, at the second stage – due to the introduction of radiation defects, in the extreme case the second stage transforms into the third stage (low electron injection mode). On the boundary between the first and the second stages transient processes are observed – restoration of emission power against its general reduction. The authors identify the heterostructures for which a pronounced effect of small doses is observed – restoration of emission power due to radiation‐induced relaxation of mechanical stresses without formation additional structural defects. The given process precedes the first stage of emission power reduction under gamma quantum irradiation. Besides, the authors identify the heterostructures which demonstrate two additional transient processes at the first stage. The researchers also establish the relations allowing describing the emission power change at the given stages. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-10-29T05:10:21.200279-05:
      DOI: 10.1002/pssc.201400072
  • Magnetic resonance in ion‐beam synthesized Fe3Si films (computer
    • Authors: N. A. Balakirev; V. A. Zhikharev
      Pages: n/a - n/a
      Abstract: High dose Fe+ ion implantation into Si assisted by an external magnetic field parallel to silicon surface results in the formation of thin granular film with pronounced uniaxial magnetic anisotropy in the film plane. It was suggested that the anisotropy is caused by the growth of elongated clusters of magnetic silicide Fe3Si. In the present work, the features of magnetic resonance spectra for two‐dimensional array of elongated clusters are numerically studied. Absorption spectra reveal anisotropy when observed in the magnetic field lying in the film plane. In magnetic field perpendicular to the film the dipole‐dipole interaction between the clusters results in a bimodal resonance signal at low level of the film filling. The dipolar field distribution over the (400x400) lattice for several values of the lattice filling is computer simulated. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-10-29T05:10:20.182638-05:
      DOI: 10.1002/pssc.201400083
  • Effect of 2.5 MeV proton irradiation on the critical parameters of
           composite HTS tapes
    • Authors: Landysh Antonova; Timofey Demikhov, Alexey Troitskii, Alexander Didyk, Alexander Kobzev, Alexander Yurasov, Sergey Samoilenkov, Galina Mikhailova
      Pages: n/a - n/a
      Abstract: In this paper we study the radiation resistance of high temperature superconductor (HTS) tapes based on GdBCO produced by SuperOx‐Japan Company to proton irradiation with an energy of 2.5 MeV in the fluence range from 6.1×1014 p/cm2 to 1×1017 p/cm2. The dependences of critical parameters on radiation fluencies were investigated. Strong influence of radiation on critical current is revealed at T=77 K in the self‐field of the sample. The change of the critical temperature dependence is not so significant. The critical current increase after proton irradiation was not revealed at the experiment conditions (at T = 77 K). The Van de Graaff accelerator in Dubna was used for the iradiation. Measurements of Tc and Ic of the samples were carried out by the DC resistive method. A radiation resistance threshold Φ = 6×1015 p/cm2 was determined. This means that the critical current does not drop by more than 20% of the initial value. The current decreases by more than an order of magnitude at Φ = 6×1016 p/cm2 and 77 K without external magnetic field. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-10-29T05:10:19.659513-05:
      DOI: 10.1002/pssc.201400104
  • Ion beam synthesis of embedded III‐As nanocrystals in silicon
    • Authors: Rim Khelifi; Mathieu Frégnaux, Yann Le Gall, Dominique Muller, Guy Schmerber, Daniel Mathiot
      Pages: n/a - n/a
      Abstract: Our goal is to use the versatility of ion beam synthesis to grow nanocrystals of InxGa1‐xAs alloys embedded in a silicon substrate. We study, first, the annealing conditions necessary to grow well defined InAs and GaAs binary nanocrystals. High dose of As, Ga and In is implanted, respectively, at 130, 130 and 180 keV to have overlapping as‐implanted profiles. The nanocrystals growth is then achieved by rapid thermal annealing at various temperatures between 650 and 800 °C for 1 min under an argon gas flow. Rutherford backscattering spectroscopy profiles show that no significant impurity out‐diffusion occurs below 800 °C for both systems. In and As thermal redistributions lead to superposed profiles. Raman spectroscopy measurements prove that InAs nanocrystals are formed above 650 °C, while 800 °C annealing is necessary to obtain GaAs nanocrystals and show that these thermal budgets are enough to fully recrystallize the implanted layer. Grazing incidence X‐ray diffraction patterns exhibit clearly InAs and GaAs related peaks. These results prove that GaAs and InAs nanocrystals can be grown in a common temperature range (700‐800 °C), opening the route to the growth of ternary InxGa1‐xAs alloys in the same conditions. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-10-29T05:10:18.297695-05:
      DOI: 10.1002/pssc.201400107
  • Contribution of iron silicide nanoparticles to the magnetic behavior of
           annealed Fe‐implanted 6H‐SiC
    • Authors: M. L. Diallo; A. Fnidiki, M. Viret, M. Drouet, D. Eyidi, A. Declémy
      Pages: n/a - n/a
      Abstract: The Fe‐implanted SiC is an interesting system in the DMS field although ion implantation induces strong microstructural defects needing post‐implantation treatments for recovery. These post‐implantation treatments often induce the formation of parasitic magnetic secondary phases. In this work, using XRD, SEM, TEM, CEMS and SQUID it is shown that post‐annealing of Fe‐implanted 6H‐SiC at 380°C with a few 1016Fe+ ions/cm2 at 900°C/60min, 1000°C/85min and 1300°C/4min enhanced the ferromagnetic ordering which can be partially explained by the formation of iron rich superparamagnetic nanoparticles. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-10-29T05:10:17.51796-05:0
      DOI: 10.1002/pssc.201400114
  • Photoluminescence properties of lamellar nano‐composites obtained by
           Cd intercalation of GaSe and GaSe:Eu single crystals
    • Authors: Dumitru Untila; Valeriu Cantser, Mihail Caraman, Igor Evtodiev, Liviu Leontie, Liliana Dmitroglo
      Pages: n/a - n/a
      Abstract: In this work surface morphology, composition and photoluminescence at 293 K and 78 K, of composite obtained by intercalation of GaSe and GaSe:Eu (0.49 at.% and 1.00 at.%) single crystal lamellas with Cd from vapor phase at 753 K and 830 K are investigated. As‐obtained composite consists of CdSe and microstructured GaSe single crystallites. Photoluminescence spectrum of GaSe:Eu single crystal lamellas is composed of Eu3+ emission band 5D0 → 7F1, 5D0 → 7F2 and 5D1 → 7F3 transitions) and indirect exciton line in GaSe crystallites. Emission spectrum of single crystalline GaSe–CdSe composite, at 78 K and 293 K, consists of donor‐acceptor band in GaSe microcrystallites and emission band of CdSe crystallites. Composite derived from the intercalation of GaSe:Eu (0.49 at.%) single crystals with Cd exhibits strong visible luminescence. Its quasi‐continuous photoluminescence spectrum is produced by superposition of luminescent emissions of CdSe nano‐ and microparticles, and microstructured GaSe. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-10-29T05:10:16.088233-05:
      DOI: 10.1002/pssc.201400127
  • Raman microscopy as a defect microprobe for hydrogen bonding
           characterization in materials used in fusion applications
    • Authors: Cédric Pardanaud; Younès Addab, Céline Martin, Pascale Roubin, Bernard Pegourié, Martin Oberkofler, Martin Köppen, Timo Dittmar, Christian Linsmeier
      Pages: n/a - n/a
      Abstract: We present the Raman microscopy ability to detect and characterize the way hydrogen is bonded with elements that will be used for ITER's plasma facing components. For this purpose we first use hydrogenated amorphous carbon samples, formed subsequently to plasma‐wall interactions (hydrogen implantation, erosion, deposition...) occurring inside tokamaks, to demonstrate how this technique can be used to retrieve useful information. We pay attention in identifying which spectroscopic parameters are sensitive to the local structure (sp3/sp2) and which gives information on the hydrogen content using isothermal and linear temperature ramp studies on reference samples produced by plasma enhanced chemical vapor deposition. We then focus on the possibility to use this fast, non‐destructive and non‐contact technique to characterize the influence of hydrogen isotope implantation in few nanometers of graphite and beryllium as C is still used in the JT‐60 tokamak and Be is used in JET and will be used as plasma‐facing component in the future reactor ITER. We also pay attention on implantation in tungsten oxide which may be formed accidently in the machine. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-10-29T05:10:15.463186-05:
      DOI: 10.1002/pssc.201400141
  • Ion‐induced degradation of phase stability and hardness of TiZrSiN
           nanocomposite thin films
    • Authors: V. V. Uglov; G. Abadias, S. N. Dub, G. N. Tolmachova, S. V. Zlotski, A. Michel, I. A. Saladukhin, S. S. Leshkevich, P. I. Gaiduk, V. Jasulaitene
      Pages: n/a - n/a
      Abstract: The effects of ion irradiation (180 keV Xe2+, doses 1×1016 cm–2 and 5×1016 cm–2) on the structure, phase composition and hardness of thin (300 nm) nanocomposite (Ti,Zr)1‐xSixNy films deposited by magnetron sputtering (silicon concentration x≤0.22) were studied. It was found that the increase in Si content results in the transformation of structure from nanocrystalline (x ≤ 0.07, grain size about 18 nm) to nanocomposite (0.07 ≤ x ≤ 0.11, grain size about 8 nm) and then to amorphous (x ≥ 0.18) state. Nanocomposite films consist of two‐phase: crystalline cubic (Ti,Zr)N grains (∼ 8 nm size) surrounded by a thin amorphous a ‐TiSiN layer. Ion irradiation with Xe ions triggers the crystallization of (Ti,Zr)N‐rich grains for amorphous films (x≥0.18). It was found that irradiation leads to a decrease in nanoindentation hardness, due to the accumulation of Xe ion in the film, as well as the elemental redistribution of solid solution constituents in the area of collisions cascades. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-10-29T05:10:13.959331-05:
      DOI: 10.1002/pssc.201400142
  • Kinetic Monte Carlo simulation of nanostructural evolution under
           post‐irradiation annealing in dilute FeMnNi
    • Authors: M. Chiapetto; C. S. Becquart, C. Domain, L. Malerba
      Pages: n/a - n/a
      Abstract: Post‐irradiation annealing experiments are often used to obtain clearer information on the nature of defects produced by irradiation. However, their interpretation is not always straightforward without the support of physical models. We apply here a physically‐based set of parameters for object kinetic Monte Carlo (OKMC) simulations of the nanostructural evolution of FeMnNi alloys under irradiation to the simulation of their post‐irradiation isochronal annealing, from 290 to 600 °C. The model adopts a “grey alloy” scheme, i.e. the solute atoms are not introduced explicitly, only their effect on the properties of point‐defect clusters is. Namely, it is assumed that both vacancy and SIA clusters are significantly slowed down by the solutes. The slowing down increases with size until the clusters become immobile. Specifically, the slowing down of SIA clusters by Mn and Ni can be justified in terms of the interaction between these atoms and crowdions in Fe. The results of the model compare quantitatively well with post‐irradiation isochronal annealing experimental data, providing clear insight into the mechanisms that determine the disappearance or re‐arrangement of defects as functions of annealing time and temperature. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-10-29T05:10:13.214493-05:
      DOI: 10.1002/pssc.201400143
  • Study on optical properties and γ‐ray irradiation resistance of
           heavy metal oxide tellurite glasses
    • Authors: Yongtao Zhou; Stefania Baccaro, Alessia Cemmi, Yunxia Yang, Guorong Chen
      Pages: n/a - n/a
      Abstract: Optical properties and irradiation resistance of heavy metal oxide tellurite glasses in the TeO2‐PbO‐Bi2O3‐B2O3 system doped with different ions are investigated. The results indicate that the matrix glass has a moderate UV cut‐off edges at about 386 nm wavelength. The UV cut‐off positions are obviously shifted to red by the addition of Ce4+. The introduction of Cr3+, Ce4+ and Ni2+ into the matrix glass exerts positive influences on irradiation resistance of glasses and cerium plays the most pronounced role. Such phenomena are mainly attributed to the variable valences of these cations. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-10-29T05:10:11.935369-05:
      DOI: 10.1002/pssc.201400148
  • The inelastic thermal spike model applied to metal/insulator interfaces
    • Authors: A. Chettah; H. Amekura, R. Baeker, H. Kucal, Y. Takeda, M. Matsuda, A. Iwase
      Pages: n/a - n/a
      Abstract: Recently, inter‐diffusion induced by 200 MeV Xe ion irradiation in metal‐insulator interfaces (Bi/Al2O3and Au/Al2O3) was investigated experimentally via in‐situ RBS measurements using 16 MeV C ions. In this work, the experimental results were tried to be explained by the inelastic thermal spike model (ITSM). Although these results explained qualitatively the inter‐diffusion, the experimentally observed diffusion length (∼800 nm) at a fluence value of 7 x 1013cm‐2was much larger than the estimated maximum value within the ITSM (∼80 nm). It was found that the Bi concentration profiles measured via in‐situ RBS could not be fitted by simple diffusional ones. We suggested that the main responsible of the huge atomic diffusion exhibited by Bi in Al2O3could be the directional motion of Bi atoms in molten Al2O3triggered off by the pressure due to liquid‐vapor phase transition of Bi near the interface. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-10-29T05:10:11.231224-05:
      DOI: 10.1002/pssc.201400149
  • Modification and reduction of defects in thin gate dielectric of MIS
           devices by injection‐thermal and irradiation treatments
    • Authors: Vladimir V. Andreev; Gennady G. Bondarenko, Vladimir M. Maslovsky, Alexander A. Stolyarov, Dmitry V. Andreev
      Pages: n/a - n/a
      Abstract: The effect of high‐field injection‐thermal and irradiation treatments on the MIS structures reliability and defect reduction in the nanoscale gate dielectric has been investigated. Injection‐thermal treatment (ITT) of MIS structures consisted of high‐field electron injection into gate dielectric with the charge of defined value and subsequent parameter stabilization of MIS structures by means of thermal annealing. The MIS structures have been studied using novel techniques of multilevel current stress. Our study shows that the ITT can improve reliability of MIS structures (increase of charge‐to‐breakdown value) and identify defective structures. The ITT provides structural modification of SiO2 and Si–SiO2 interfaces. It has been shown that the ITT at elevated temperatures can reduce the reliability of MIS devices. Performing ITT at high temperatures leads to decrease of charge‐to‐breakdown average value in MIS structures. It has been demonstrated that irradiation treatment allows to reduce density of defects in thermal SiO2 films, SiO2 films doped with phosphorus, oxynitride films and as a result to increase reliability of MIS devices. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-10-29T05:10:09.449695-05:
      DOI: 10.1002/pssc.201400151
  • Thermodynamic analysis of defect formation in BiFeO3
    • Authors: T. Tchelidze; T. Gagnidze, A. Shengelaya
      Pages: n/a - n/a
      Abstract: In this paper the thermodynamic analysis of equilibrium concentration of defects for the system BiFeO3(solid)‐O2 (gas) is carried out. The analysis is performed by the Kroger method of quasi‐chemical equations. The concentration of defects and free carriers vs. oxygen partial pressure in surrounding atmosphere at definite temperature are obtained. The calculations were carried out for 3 nm BiFeO3 nanowires too. When the defects ionization energies and material band gap are increased in nanowires, the picture of defects thermodynamics is changed. In 3 nm nanowire the area of self‐compensation is significantly broadened. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-10-29T05:10:08.322224-05:
      DOI: 10.1002/pssc.201400153
  • Low temperature hydrogenated microcrystalline silicon‐carbon alloys
           deposited by RF‐PECVD
    • Authors: Sofia Gaiaschi; Marie‐Estelle Gueunier‐Farret, Erik V. Johnson
      Pages: n/a - n/a
      Abstract: Two sets of hydrogenated microcrystalline silicon carbon alloys were deposited by standard radio frequency (RF) plasma enhanced chemical vapor deposition at a substrate temperature of 175 °C. The effect of the methane flow rate and of the RF‐power were investigated. Samples were deposited from a silane and methane gas mixture, highly diluted in hydrogen. The increase in methane flow rates leads to a decrease of the crystalline volume fraction and an increase in carbon incorporation. On the other hand, decreasing the RF‐power shifts the microcrystalline‐to‐amorphous transition at higher methane flow rates. Moreover, for similar amount of carbon incorporated, the decrease in RF‐power leads to materials showing higher crystalline volume fraction and average grains sizes. Both ion bombardment energy and carbon incorporation contributes to the microstructural properties of the deposited alloys. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-10-10T08:20:57.60578-05:0
      DOI: 10.1002/pssc.201400034
  • Nanoscale electrical characterization of graphene contacts to AlGaN/GaN
    • Authors: Gabriele Fisichella; Giuseppe Greco, Salvatore Di Franco, Fabrizio Roccaforte, Sebastiano Ravesi, Filippo Giannazzo
      Pages: n/a - n/a
      Abstract: In this paper, we describe a highly reproducible method to transfer graphene (Gr) grown on copper by chemical vapour deposition to the surface of AlGaN/GaN heterostructures and we report a nanoscale electrical characterization of current transport at Gr contact to AlGaN. This latter investigation has been carried out using local current‐voltage measurements by conductive atomic force microscopy (CAFM), performed both on the Gr‐coated and bare AlGaN surface (reference). These analyses provide information on the lateral uniformity of the Schottky barrier height (SBH) between Gr and AlGaN. Gr contacts to AlGaN exhibit much more uniform and significantly lower SBH (∼0.4 eV) than common metals, such as gold, with SBH∼0.96 eV. These results can be useful for future applications in high frequency transistors based on AlGaN/GAN heterostructures and Gr. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-10-10T08:20:56.325426-05:
      DOI: 10.1002/pssc.201400078
  • Thermodynamic study of the ternary system
    • Authors: N. Elayech; H. Fitouri, Y. Essouda, A. Rebey, B. El Jani
      Pages: n/a - n/a
      Abstract: Binary thermodynamic data, successfully used for phase diagram calculations of binary system Ga‐As, Ga‐Bi and As‐Bi were used for prediction of phase equilibria in ternary Ga‐As‐Bi system. The parameters for the thermodynamic models of the constituent binary systems and those for the Ga‐As‐Bi system are optimized in this study using data on phase equilibria and data on the different alloys available in the literature and calculated in the present work. The implications of the phase data for solution epitaxy are discussed. The liquidus surface and isothermal section were calculated. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-10-10T08:20:54.653667-05:
      DOI: 10.1002/pssc.201400147
  • Optical properties of plasmonic nanoparticles distributed in size
           determined from a modified Maxwell‐Garnett‐Mie theory
    • Authors: Y. Battie; A. Resano‐Garcia, N. Chaoui, A. En Naciri
      Pages: n/a - n/a
      Abstract: The optical properties of spherical gold and silver nanoparticles distributed in size are investigated through a new effective medium theory. It is about the modified Maxwell‐Garnett‐Mie theory (MMGM) that takes into account the intrinsic confinement, dynamic effects and the nanoparticle radius distribution. In the case of monodispersed nanoparticles with a radius in the 1 nm‐25 nm range, MMGM is equivalent to the Mie theory. Compared to the conventional effective medium theory, we demonstrate that MGMM gives better description of the measured extinction spectra of colloidal gold and silver solutions. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-10-10T08:20:53.365108-05:
      DOI: 10.1002/pssc.201400190
  • Monte Carlo study of the early growth stages of 3C‐SiC on
           misoriented <11‐20> and <1‐100> 6H‐SiC
           substrates: role of step‐island interaction
    • Authors: M. Camarda; A. La Magna, F. La Via
      Pages: n/a - n/a
      Abstract: In this paper, we use three‐dimensional kinetic Monte Carlo simulations on superlattices to study the hetero‐polytypical growth of cubic silicon carbide polytype (3C‐SiC) on hexagonal 6H‐SiC step‐bunched substrates with miscuts towards the and directions. We find that the preferential 3C conversion observed on misoriented substrates could be due to a different step‐to‐island interaction which enhances island stability and expansion in this specific direction. For this reason 3‐4 degrees off step‐bunched 6H substrates with miscut towards the direction should be the best choice for the stable and reproducible hetero‐polytypical growth of high quality cubic epitaxial films. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-10-10T08:20:52.000426-05:
      DOI: 10.1002/pssc.201400197
  • Green light‐emitting CdTe nanocrystals: synthesis and optical
    • Authors: Luciana Algieri; Roberta Rosato, Maria Elena Mosca, Maria Lucia Protopapa, Anna Grazia Scalone, Francesca Di Benedetto, Luigi Bucci, Leander Tapfer
      Pages: n/a - n/a
      Abstract: In this work, we report on the synthesis of CdTe nanocrystals (NCs) by using of two different saturated long‐chain capping ligands, oleic (OA) and myristic acids (MA), and investigate their influence on the nanocrystals optical properties. The main goal of our study is to identify the ligand that allows slowing down the growth rate of the NCs after nucleation, in order to obtain small enough nanocrystals emitting in the blue‐green part of the optical spectrum. Our results show clearly that oleic acid allows a good control on the CdTe NCs growth, finally leading to a fine‐tuning of the NCs size‐dependent emission from the green to the yellow part of the spectrum. Instead, a faster reaction kinetics, which arises in a lower possibility to produce small NCs emitting in the green part of the spectrum, was noticed using myristic acid. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-10-10T08:20:50.640015-05:
      DOI: 10.1002/pssc.201400203
  • Electroluminescence of germanium LEDs on silicon: Influence of antimony
    • Authors: Bernhard Schwartz; André Klossek, Martin Kittler, Michael Oehme, Erich Kasper, Jörg Schulze
      Pages: n/a - n/a
      Abstract: Antimony‐doped Ge‐LEDs were subjected to electroluminescence studies at temperatures about 300 K and 80 K. The LEDs were grown on Si substrates by MBE. The thickness of the active layer was 300 nm. For the p+nn+‐LEDs the Sb concentrations were 1 × 1018, 1 × 1019, 3 × 1019, 4 × 1019, 7 × 1019 or 1 × 1020 cm–3, respectively. As reference a p+in+‐LED without intentional doping in the active layer was used. The investigated specimen exhibited dominance of the direct transition line at about 0.8 eV. Moreover, luminescence indirect transition was observed. In general, the spectra reveal higher EL intensities at room temperature as compared to 80 K. With decreasing temperature the direct peak was blue shifted. The highest EL intensity was found for the LED with Sb concentration of 3 × 1019 cm–3. With increasing Sb doping a red‐shift of the direct peak was observed, caused by band gap narrowing. In addition, a simulated curve of the direct transition was compared with our samples and fits well with the measured spectra. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-10-10T08:20:49.145608-05:
      DOI: 10.1002/pssc.201400056
  • Silicon film deposition on crystalline, sintered and powder substrates
           using an inline optical processing CVD system
    • Authors: André Augusto; Filipe Serra, António Vallêra, João M. Serra
      Pages: n/a - n/a
      Abstract: An inline optical CVD process operating at low temperature (10 mm/min) inside the furnace. Solid silicon substrates were laser textured to reduce the reflectivity, leveraging the growth rates. Laser patterning has a strong influence in the growth rate, reaching values up to 9 µm/min. Using pressed silicon powder substrates, growth rates increase dramatically to 40‐90 µm/min. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-09-30T14:40:28.076031-05:
      DOI: 10.1002/pssc.201400126
  • Properties of electrodeposited germanium thin films
    • Authors: Yasutaka Uchida; Tomoko Funayama, Yoshiaki Kogure, Kazuyoshi Ueno
      Pages: n/a - n/a
      Abstract: In this paper, the results of Ge film deposited by electroplating method was studied and showed the possibility of making a NIRS sensor by the Ge film. Cu/Ti double layer structure could use the cathode electrode on the glass substrate during the GeCl4 electroplating. The deposition rate of electroplating Ge film was 100 nm/h, however, that rate was improved to 570 nm/h by introducing a spacer between Cu thin film and extraction electrode and Ar gas bubbling. The oxygen content of as‐deposited film was about 10%, however, this value reduced to lower than 1% by using the Ar bubbling. The deposited film was amorphous and its optical band gap was 0.73 eV. 200 nm‐thick Ge film was formed on flexible substrate by electroplating method. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-09-30T14:40:27.001746-05:
      DOI: 10.1002/pssc.201400094
  • Effect of total gas pressure in sputtered hydrogenated amorphous silicon
    • Authors: Abdelkrim Fedala; Aghilas Dad, Moussa Khefiani‐Guellil, Sonia Tata, Claude Simon, Tayeb Mohammed‐Brahim
      Pages: n/a - n/a
      Abstract: Hydrogenated amorphous silicon (a‐Si:H) thin films are prepared using DC magnetron sputtering method at a substrate temperature of 200 °C using a plasma of argon and hydrogen gas mixture. The effects of the total gas pressure (TGP) during the deposition on structural, optical and electrical properties of the films are investigated. A decrease of the polyhydride bonding groups concentration (SiHn) is observed in FTIR spectra when the TGP increases. The optical gap remains constant. With increasing TGP the dark and photoconductivity increase, the defect density of states determined from constant photocurrent method (CPM) decreases, and the quantum efficiency mobility lifetime product (ημτ) is enhanced by a factor of more than fifty. Thus, the structural and electrical properties are enhanced by only increasing the TGP. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-09-30T14:40:25.827951-05:
      DOI: 10.1002/pssc.201400070
  • Structural and photoconductivity properties of silicon carbon thin films
    • Authors: U. Coscia; G. Ambrosone, D. K. Basa, V. Rigato, S. Binetti
      Pages: n/a - n/a
      Abstract: Nanostructured films composed of silicon crystallites dispersed in an hydrogenated amorphous silicon carbon matrix have been deposited by plasma enhanced chemical vapour deposition from silane‐methane mixtures diluted in hydrogen by varying the rf power. Compositional, structural, optical and photoconductivity properties of the films have been investigated. The increase in rf power in the 40‐80 W range enhances the incorporation of carbon and hydrogen in the amorphous matrix and decreases the volume fraction and size of the silicon crystallites leading to an enlargement of the optical band gap from 2.07 to 2.20 eV. Steady state photoconductivity measurements, performed under monochromatic radiations in the visible range, have demonstrated the occurrence of monomolecular recombination kinetics in the samples under illumination and that the mobility‐lifetime product of the free electrons as a function of the optical gap decreases from 1.9 × 10–7 to 2.5 × 10–9 cm2V–1 as in the case of device quality films deposited by silane‐methane mixtures diluted in hydrogen. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-09-30T14:40:24.646207-05:
      DOI: 10.1002/pssc.201400063
  • Analysis of the reduction of tensile stress by post‐growth annealing
           methods in multicrystalline silicon wafers produced by the RST process
    • Authors: O. Martínez; A. Tejero, E. Tupin, M. A. González, J. Jiménez, C. Belouet, C. Baillis
      Pages: n/a - n/a
      Abstract: In this work, we analyze the residual stress, in both as‐grown and post‐growth annealed silicon ribbon on a sacrificial carbon template, by the simulation of the thermo‐mechanical behavior of the cooling ribbon using the Abaqus software, and the measurement of stress on the free silicon surface by µ‐Raman spectroscopy. The results of the simulations gave limits within which flat ribbons could be obtained for a combination of silicon thickness, ribbon width and pull rate. Stress relaxation by off‐line thermal treatments is used to optimize a post‐growth annealing furnace in line with the ribbon growth system. The fragile behavior of the ribbon during laser cutting can be considerably reduced by a short relaxation of the ribbon at medium temperatures around 850 °C, which were observed to give the best behavior in terms of residual tensile stress relaxation. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-09-30T14:40:22.957361-05:
      DOI: 10.1002/pssc.201400047
  • Oxygen gettering in low‐energy arsenic or antimony ion implanted
    • Authors: O. Oberemok; V. Kladko, V. Litovchenko, B. Romanyuk, V. Popov, V. Melnik, J. Vanhellemont
      Pages: n/a - n/a
      Abstract: Low energy As or Sb ion implantation followed by furnace annealing was used to create ultra shallow junctions. It was found that a significant amount of oxygen was redistributed from the Si bulk to the As implanted layer leading even to an increase of the screening oxide film thickness. Using a marker layer created by implantation of 18O ions, it was confirmed that a large number of interstitial oxygen atoms are transferred from the bulk of the Si wafer to the wafer surface during implanted As activation annealing. Estimation of the O diffusivity in Si during the 950 °C activation anneal, yields a value of about 10–10 cm2 /s which is more than an order of magnitude larger than the literature value which is close to 7 × 10–12 cm2/s. In the case of Sb implantation, the oxygen gettering effect is much reduced. This difference in oxygen behavior can be attributed to the influence of mechanical stress in the near surface highly doped layer. The configuration of the mechanical stress field is different for the cases of As and Sb implantation, with tensile stress dominating for the latter. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-09-17T14:10:20.912161-05:
      DOI: 10.1002/pssc.201431562
  • Room temperature kerfless silicon thin foils obtained via a stress
           inducing epoxy layer
    • Authors: João Serra; Pierre Bellanger, Pierre O. Bouchard, Marc Bernacki
      Pages: n/a - n/a
      Abstract: We present 5 × 5 cm2 SLIM‐cut foils obtained by cooling form curing temperatures of 150 °C to room temperature using an epoxy stress inducing layer. Numerical simulations were performed to help the definition of an optimum geometry and we demonstrate the capability to obtain several thin foils from the same substrate. The evolution of minority carrier lifetime upon successive exfoliation of the same substrate is presented. Measured lifetimes in these silicon foils increase after etching suggesting that recombination centers are present close to the foil surface. Effective lifetimes of 50 microseconds were obtained in 120 µm thick foils, corresponding to diffusion length much larger than the foil thickness. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-09-17T14:10:18.426638-05:
      DOI: 10.1002/pssc.201400105
  • An amazing semiconductor choice for high‐frequency FET:
           H‐terminated polycrystalline diamond film prepared by DC arc jet CVD
    • Authors: C. M. Li; J. L. Liu, L. X. Chen, J. J. Wei, L. F. Hei, J. J. Wang, Z. H. Feng, H. Guo3
      Pages: n/a - n/a
      Abstract: With the development of information and communication technology, conventional semiconductors such as Si and GaAs cannot satisfy the requirement of high‐frequency and high‐power electronic devices. By contrast, diamond film has been considered to be a potential material alternative due to the highest Johnson and Keyse figures of merit. In this paper, H‐terminated polycrystalline diamond films with different quality were prepared by DC arc jet CVD through adjusting the deposition conditions. The conductive behaviour of p‐type channel on H‐terminated diamond surface was compared and analyzed based on the N‐related impurity and spontaneous polarization model. After that, MESFETs (metal‐semi‐conductor field effect transistor) were fabricated on H‐terminated diamond and the radio frequency (RF) performance was evaluated. The cut off frequency (fT) of 11 GHz and the maximum oscillation frequency (fmax) of 18.5 GHz for MESFET in our situation were obtained. It was found that equivalent circuit elements were lower or comparable with the reported values for the FETs with the highest fT and fmax except the gate capacitance, which indicates that the carrier mobility should be improved further for high‐frequency devices application. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-09-17T14:10:16.294012-05:
      DOI: 10.1002/pssc.201400076
  • Processing‐induced near‐interfacial thermal donor generation
           in (100)Si/Si‐oxycarbide insulator structures revealed by electron
           spin resonance
    • Authors: S. Iacovo; A. Stesmans, S. Nguyen, V. V. Afanas'ev
      Pages: n/a - n/a
      Abstract: Low temperature electron spin resonance (ESR) study of Cz‐(100)Si/insulator structures with organosilicate films of low dielectric constant κ grown at 300 °C using plasma‐enhanced chemical vapor deposition (PECVD) reveals, after subjection to UV‐irradiation assisted thermal curing at 430 °C to remove organics, the observation of the NL8 ESR spectrum. This indicates the generation in the c‐Si substrate of singly ionized thermal double donor (TDD) defects with a core contained of oxygen atoms. The generation is found to be highly non uniform, which is concluded to be the result of interfacial stress acting as the major driving component in the enhancement of TDD formation during thermal treatment. This suggests substantial stress being involved with PECVD organosilicate low‐κ glasses. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-09-17T14:10:14.279615-05:
      DOI: 10.1002/pssc.201400064
  • Properties of a‐SiGe:H thin films: correlation between
           photosensitivity density of states
    • Authors: Lamia Laidoudi; Abdelkrim Fedala, Abla Rahal
      Pages: n/a - n/a
      Abstract: Thin films of hydrogenated amorphous silicon germanium (a‐Si1‐xGex:H) alloy are prepared using DC magnetron sputtering method, at a substrate temperature of 150 °C. Silicon and germanium are co‐pulverized. All our films are deposited in the same preparation conditions except for those having a germanium content from 27% to 40%. Structural, optical and electrical properties are systematically studied from IR absorption, optical transmission and electrical measurements. Hydrogen content is determined by integrating the wagging mode infrared absorption. The increase of the Ge content from 27% to 40% is responsible for a decrease in optical bandgap of 1.59 to 1.43 eV and a reduction of the total content of hydrogen bonds in both Si‐H and Ge‐H configurations. A good correlation is observed between the reduction of the optical gap and the increase of one order of magnitude of the dark conductivity. The white light sensitivity shows a significant degradation due to germanium incorporation in the silicon matrix. Therefore, this degradation increases with germanium content. The density of states (DOS) located at the Fermi level g(EF) is estimated from the analysis of capacitance‐frequency measurements on Au/a‐Si1‐xGex:H/c‐Si(N+) Schottky structure, in zero bias condition. In our layers, the turn on condition which permits to measure the complete response of the deep states, for 1 kHz frequency, occurs at a relatively high temperature (over 75 °C). The measured density of states increases from 3x1016 cm‐3 eV‐1 to 3x1018 cm‐3 eV‐1 when the germanium content increases. This can highlight the narrow correlation between sensitivity degradation and density of states augmentation. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-09-17T14:10:12.440977-05:
      DOI: 10.1002/pssc.201400059
  • Effect of nitrogen mole fraction on hydrogenated amorphous silicon nitride
           deposited by DC magnetron sputtering: transition between metallic and
           reactive sputtering
    • Authors: Kamel Mokeddem; Mohamed Kechouane
      Pages: n/a - n/a
      Abstract: The hydrogenated amorphous silicon nitride thin films are deposited by DC magnetron sputtering in argon, molecular hydrogen and nitrogen plasma mixture. The films are deposited at 150 °C and at 130 W sputtering power with wide range of nitrogen mole fraction. The plasma is characterized by the target voltage measurement. The samples are characterized by the optical transmission measurements and the physicochemical structure is studied by the FTIR absorption spectroscopy. When the nitrogen mole fraction increases from 0.075 to 0.24 the target voltage decrease from 413 to 325 V and increases suddenly to 450 V when nitrogen mole fraction increases to 0.69. The decrease of target voltage may be due to the transition from metallic to reactive sputtering process and its increase can be explained by the implantation of reactive ions in the target. Sputtering rate and refractive index decrease respectively from 8.33 to 1.73 Å/sec and from 2.52 to 1.68 with nitrogen mole fraction. The value of refractive index at critical nitrogen mole fraction is about 1.8. When the nitrogen mole fraction increases the frequency related to Si‐H band, on FTIR spectrum, shift from 2097 cm‐1 to reach 2209 cm‐1 at the critical nitrogen mole fraction. Thereafter it varies sharply to 2190 cm‐1 and remains constant. A sudden change is observed on the sputtering rate, on the intensity of the band attributed to the stretching vibration of N‐H and Si‐H bonds. From these results we believe that the stoichiometric composition is reached at the critical nitrogen mole fraction and beyond this the deposited films are rich of nitrogen and hydrogen. This is consistent with the explanation given of the variation of the target voltage. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-09-17T14:10:10.419148-05:
      DOI: 10.1002/pssc.201400058
  • Non‐contact high precision alternative to Hg‐probe for dopant
           profiling in SiC
    • Authors: Andor Czett; Csaba Buday, Sasha Savtchouk, Dmitriy Marinskiy
      Pages: n/a - n/a
      Abstract: The silicon carbide industry has been expanding in the recent years, producing a search for SiC non‐contact electrical characterization methods capable of replacing the commonly used Hg‐probe technique. In this work we present doping metrology based on the corona‐Kelvin method, which was originally developed and used for silicon IC dielectric and interface characterization. The method employs corona discharge in air to deposit precise doses of charge on the SiC surface. The corresponding depletion voltage is then measured with a Kelvin probe enabling non‐contact determination of the static charge‐voltage and capacitance‐voltage characteristics. The approach incorporates three novel elements: 1. corona charging of SiC to high depletion voltage with constant surface potential method; 2. the derivative charge‐voltage measurements for d(1/C2)/dV analysis and doping profiling; 3. surface charge neutralization with appropriate SiC illumination for repeated measurements. We demonstrate excellent repeatability and accuracy of the novel approach for n and p‐type SiC doping measurements in a range from 1014cm‐3 to mid 1018cm‐3 and excellent correlation with results obtained with mercury‐probe C‐V. Using multi‐layer epitaxial SiC structures, we further demonstrate the effectiveness of novel non‐contact depth profiling. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-09-17T14:10:07.925429-05:
      DOI: 10.1002/pssc.201400057
  • Silicon nanowires: synthesis, optical properties and applications
    • Authors: Cristiano D'Andrea; Maria José Lo Faro, Paolo Musumeci, Barbara Fazio, Fabio Iacona, Giorgia Franzò, Pietro Gucciardi, Cirino Vasi, Francesco Priolo, Alessia Irrera
      Pages: n/a - n/a
      Abstract: Group‐IV semiconductor nanowires (NWs) are attracting the interest of a wide scientific community as building blocks for a wide range of future nanoscaled devices. We used metal‐assisted chemical etching of Si substrates to synthesize Si NWs with different length and nanometer‐size diameter. NWs obtained by this technique have exactly the same structure and doping of the substrate and present quantum confinement effects. Photoluminescence (PL) emission at room temperature from Si NWs is reported. We observed an increasing behaviour of the PL intensity as a function of the NWs length. The fabrication of light emitting devices based on Si NWs, showing electroluminescence emission at room temperature under low voltage excitation, is also reported. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-09-12T05:10:13.275103-05:
      DOI: 10.1002/pssc.201400052
  • Ion beam analysis of Heusler alloy Fe3Si epitaxially grown on Si(111)
    • Authors: Yoshihito Maeda; Yuki Kawakubo, Yuya Noguchi, Kazumasa Narumi, Seiji Sakai
      Pages: n/a - n/a
      Abstract: We have investigated atomic ordering of Heusler alloy Fe3Si(111) epitaxially grown on Si(111) by using ion beam analysis. The total atomic displacement along Si directions was deduced from the minimum yield χmin and the critical angle Ψ1/2 for channeling. The total displacement consists of both one‐dimensional thermal vibrations computed by the Debye theory and static displacements due to imperfections, lattice mismatch, thermal expansion etc. The atomic displacement increased as the annealing temperature increased from 373 to 573 K. We found that this static displacement came from a difference in thermal expansion between the Fe3Si film and Si substrates at the anneal temperature and was quenched into room temperature as a remnant displacement. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-09-12T05:10:12.417819-05:
      DOI: 10.1002/pssc.201400027
  • First principles analysis of atomic configurations of group IV elements in
           Ge crystal for solar cells
    • Authors: Ryo Matsutani; Koji Sueoka, Eiji Kamiyama
      Pages: n/a - n/a
      Abstract: We focused on group IV semiconductors, i.e., Ge (Si), containing C, Si (C, Ge), and/or Sn atoms as alternative candidates for poly‐Si crystals to achieve higher engineering efficiency in solar cells in this research. The main target of this study was to obtain basic data on atomic configurations, such as bond strain and stable sites for substituted C, Si, and Sn atoms in Ge and for C, Ge, and Sn atoms in Si crystals through first principles analysis. We found that ((C, Si)/C) atoms with smaller covalent radii than (Ge/Si) formed tensile local strain along zigzag bonds in the direction while (Sn/(Ge, Sn)) atoms with larger covalent radii than (Ge/Si) formed compressive local strain. Another important result was that local strains except for zigzag bonds had opposite signs to strains along zigzag bonds. The main results to summarize stable configurations of substitutional IV elements were: (1) C and Sn (Si) atoms were stable at positions next to one another, while Si and Sn atoms were stable at mostly separated positions in Ge crystals. (2) C (Ge) and Sn atoms were stable at positions next to one another, while C and Ge atoms were stable at mostly separated positions in Si crystals. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-09-12T05:10:11.555634-05:
      DOI: 10.1002/pssc.201400029
  • Influence of copper contamination on the illuminated forward and dark
           reverse current‐voltage characteristics of multicrystalline
           p‐type silicon solar cells
    • Authors: Tleuzhan Turmagambetov; Sébastien Dubois, Jean‐Paul Garandet, Benoit Martel, Nicolas Enjalbert, Jordi Veirman, Etienne Pihan
      Pages: n/a - n/a
      Abstract: We studied the influence of copper (Cu) on the performances of conventional photovoltaic (PV) solar cells by growing two multicrystalline (mc) boron‐doped silicon (Si) ingots from ultra‐pure feedstocks, one of these feedstocks being deliberately contaminated with 90 ppm wt of Cu. Industrial‐like solar cells were fabricated and the associated external gettering and hydrogenation effects were studied. An originality of our approach consisted in evaluating the forward but also reverse current‐voltage (I‐V) characteristics of the fabricated cells. Furthermore we assessed the stability under illumination of the PV parameters as Cu is known to be responsible for light‐induced degradations (LID) of the carrier lifetime. On the one hand we unexpectedly showed that the PV conversion efficiency (η) was not affected by the initially large Cu concentrations. We demonstrated that it was due to the complementary actions of the external gettering effect developed by the phosphorus‐diffusion and the bulk hydrogenation. The Cu‐addition slightly enhanced the pn junction hard breakdown, however the extracted junction breakdown voltages fulfilled the common industrial requirements for this parameter. On the other hand we highlighted significant decreases under illumination of the PV performances for the Cu‐contaminated solar cells fabricated from wafers coming from the upper part of the ingot (i.e., samples with the highest Cu concentration). These decreases could be explained by the previously proposed mechanisms in the literature, which argue that the excess charge carriers could reduce the electrostatic repulsion between interstitial Cu ions and Cu precipitates, this effect enhancing the Cu precipitation. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-09-12T05:10:10.418578-05:
      DOI: 10.1002/pssc.201400036
  • Quantitative analysis of carbon impurity concentration in silicon
           epitaxial layers by luminescence activation using carbon ion implantation
           and electron irradiation
    • Authors: Satoko Nakagawa; Kazuhiko Kashima
      Pages: n/a - n/a
      Abstract: The calibration curve for the carbon concentration in silicon epitaxial layers was obtained by photo‐luminescence spectroscopy after carbon ion implantation and electron irradiation. Low carbon concentrations on the order of 1014 atoms/cm3 affected properties such as the on‐resistance and carrier lifetime of insulated gate bipolar transistors (IGBTs). We focused on carbon impurities because interstitial carbon can form complexes, such as complexes of interstitial and substitutional carbon (Ci‐Cs) and of interstitial carbon and oxygen (Ci‐Oi), which produce deep levels in the energy band gap. To verify the effects of carbon impurities separately from those of oxygen impurities, oxygen‐free silicon epitaxial layers were studied. The carbon concentration in silicon epitaxial wafers was evaluated quantitatively by using our calibration curve. Carbon ion implantation and photoluminescence spectrum measurements were performed to obtain the slope of the calibration curve. In addition, secondary ion mass spectrometry measurement gave absolute carbon concentration against photo‐luminescence intensity for fixing the calibration curve. The calibration curve was used to determine the carbon concentration for each IGBT. Carbon impurity concentrations as low as 1014 atoms/cm3 in silicon epitaxial layers lowered device performance. Therefore, decreasing the carbon impurity concentration is essential for improving the performance of advanced IGBTs. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-09-12T05:10:09.410256-05:
      DOI: 10.1002/pssc.201400046
  • Outdoor characterization of amorphous silicon based photovoltaic modules
           with different structures
    • Authors: Thomas Mambrini; Anne Migan‐Dubois, Christophe Longeaud, Mustapha Elyaakoubi
      Pages: n/a - n/a
      Abstract: Three different amorphous silicon structures of PV modules were analyzed in outdoor condition during one month. The Staebler‐Wronski effect (or light induced degradation effect) is well known for the amorphous technology and depends strongly on the manufacturing process and its structure. Due to this effect, the amorphous PV modules loose performances compared to their initial characteristics. The behaviour, during and after the aging of different amorphous silicon PV module, is investigated and a new amorphous structure, less sensitive to the Staebler‐Wronski effect and with a better response under real conditions of use is exposed. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-09-12T05:10:08.507824-05:
      DOI: 10.1002/pssc.201400048
  • Multi‐frequency electron spin resonance study of inherent Si
           dangling bond defects at the thermal (211)Si/SiO2 interface
    • Authors: S. Iacovo; A. Stesmans
      Pages: n/a - n/a
      Abstract: Multifrequency low temperature electron spin resonance (ESR) studies were carried out to atomically assess inherent point defects at the thermal ‘higher index' (211)Si/SiO2 interface. This reveals, as dominant imperfections, Pb‐type centers (generic entity Si3≡Si•, the dot representing an unpaired sp3‐like hybrid) occurring in densities of ∼1 × 1013 cm–2 for oxidation temperatures ∼400 °C. On the basis of the pertinent ESR characteristics, the inherent basic defect is typified as the Pb0(211) variant, resembling closely the Pb0 center in standard (100)Si/SiO2. At the higher index (211)Si/SiO2 interface, these defects predominantly pertain to defected Si atoms located at (111)‐face terraces. Combination of angular and frequency (ν) dependent studies show the Pb0(211) peak‐to‐peak line width ΔBpp to be composed of a residual width (ν→0) of 2.2 ± 0.1 G, to which dipolar broadening contributes an essential part, and a substantial inhomogeneous broadening component due to g distribution, predominantly in g⊥, induced by non‐uniform interface strain –also similar to the Pb0(100) properties. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-08-08T04:40:13.233383-05:
      DOI: 10.1002/pssc.201400071
  • Sol–gel deposited phosphorus and boron doped thin silica films for
           diffused n+p and n+pp+ structures
    • Authors: Armel Duvalier Pene; Bouchaib Hartiti, Laurent Bitjoka, Phillippe Thevenin, Cesar Kapseu
      Pages: n/a - n/a
      Abstract: The realization of a silicon solar cell emitter is a critical and very important step in photovoltaic technology. Indeed, the surface concentration of boron (B) or phosphorus (P) and junction depth determines the photovoltaic conversion efficiency of silicon solar cells. Several techniques are used for the realization of emitters n+p and n+pp+ among which the vapor diffusion, ionic implantation and diffusion from solid sources are the most common. This work will be devoted to the realization of emitters made by diffusion of P or B from solid doping sources developed by the sol–gel method associated to spin coating on monocrystalline and polycrystalline silicon wafers. The doping solutions were prepared by sol–gel method using methyltriethoxysilane “MTEOS” or tetramethoxysilane “TEOS” and H4PO3 or H3BO3 as precursors. The n+ junction was realized by emulsion of phosphoric acid in isopropanol while the p+ junction was obtained by emulsion of boric acid H3BO3 in isopropanol or by diffusion of aluminium at high temperatures. Our samples were annealed at temperatures ranging from 850 to 1000 °C in a classical furnace under Nitrogen atmosphere. The four point technique has been used to study the electrical properties of n+p and n+pp++ structures. The results of measurements showed values of the sheet resistance Rs comparable to those of literature and confirm the diffusion of phosphorus and boron from liquid and solid sources prepared by sol–gel method. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-08-08T04:40:12.172213-05:
      DOI: 10.1002/pssc.201400060
  • Temperature dependent switching behaviour of nickel silicided undoped
           silicon nanowire devices
    • Authors: Jürgen Beister; Andre Wachowiak, André Heinzig, Jens Trommer, Thomas Mikolajick, Walter M. Weber
      Pages: n/a - n/a
      Abstract: In this work, we investigate the temperature dependence of electrical switching properties of back‐gated, undoped Si‐nanowire field‐effect transistors with Ni‐silicided source/drain contacts. A simple, phenomenological model illustrates the leading order temperature dependence of the source‐drain current, which originates predominantly from charge carrier injection by tunneling through the Schottky junction. Drain current versus gate voltage measurements have been performed for various temperatures and several drain voltages on a single nanowire device. The temperature dependence of the drain‐source current for specific gate and drain voltages is analysed within the framework of voltage dependent effective barrier heights. As a result, the temperature dependence of the tunnelling current is not only important for the sub‐threshold region, but also plays a significant role in the transistor “on‐state”. In addition, the effective barrier heights for electrons and holes tend towards the natural Schottky barriers of the NiSi2‐Si interface, if the applied external fields generate the case of flat band condition at the injection Schottky barrier, i.e. in the deep “off‐state” region. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-08-08T04:40:10.98697-05:0
      DOI: 10.1002/pssc.201400055
  • Band engineering and absorption spectra in compressively strained
           Ge0.92Sn0.08/Ge (001) double quantum well for infrared photodetection
    • Authors: N. Yahyaoui; N. Sfina, J.‐L. Lazzari, A. Bournel, M. Said
      Pages: n/a - n/a
      Abstract: We report a theoretical investigation of strained Ge1−xSnx/Ge (001)‐oriented quantum wells as a bulding block in active region of infrared photodetector. The electronic band parameters, gaps, discontinuities and effective masses for heterointerfaces between compressively strained Ge1−xSnx and relaxed Ge have beencomputed at room temperature. From this preliminary and mendatory work, we conclude that pseudomorphic Ge1−xSnx alloys become direct band gap semiconductors at a Sn‐fraction of 15.3%, e.g. a lattice mismatch as high as 2.3%. Due to achievable critical layer thickness and mainly solid solubility limit, a type‐I compressively strained Ge/Ge0.92Sn0.08/Ge (double) quantum well is studied by solving Schrödinger equation without and applied bias voltage. A strong absorption coefficient (> 1×104 cm−1) and a Stark shift of the direct transition between 2.01 μm and 2.25 μm at large external fields (40kV/cm) are attractive characteristics for the design of infrared photodetectors (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-08-08T04:40:09.615156-05:
      DOI: 10.1002/pssc.201400054
  • Electrically detected magnetic resonance study on defects in Si
           pn‐junctions created by proton implantation
    • Authors: Gernot Gruber; Stefan Kirnstoetter, Peter Hadley, Markus Koch, Thomas Aichinger, Holger Schulze, Werner Schustereder
      Pages: n/a - n/a
      Abstract: The present study focuses on electrically detected magnetic resonance (EDMR) investigations of proton implanted silicon. The samples were prepared on n‐type silicon wafers highly doped diffused boron (B) p‐region, forming a pn‐junction. A large additional n‐type doping was introduced by proton (H+) implantation. We compare samples with implantation doses up to 1015 H+/cm–2 and investigate the effects of anneals at 350 °C. We observe different types of defects in the differently prepared samples. One doublet with 118.5 G HF splitting and a g ‐value of 2.0095(4) is only observed in the samples implanted with the highest dose and is assigned to hydrogen. The structure of the other observed defects remains unidentified and can only tentatively be assigned to hydrogen. More extensive measurements would have to be performed to get a better picture. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-08-08T04:40:08.136114-05:
      DOI: 10.1002/pssc.201400053
  • High dose proton implantations into silicon: a combined EBIC, SRP and TEM
    • Authors: Stefan Kirnstoetter; Martin Faccinelli, Christian Gspan, Werner Grogger, Moriz Jelinek, Werner Schustereder, Johannes G. Laven, Hans‐Joachim Schulze, Peter Hadley
      Pages: n/a - n/a
      Abstract: Proton (H+) implantations are used in power semiconductor devices to introduce recombination centers (Hazdra et al., Microelectron. J. 32(5), 449–456 (2001)) or to form hydrogen related donor complexes (Zohta et al., Jpn. J. Appl. Phys. 10, 532–533 (1991)). Proton implantations are also used in the 'smart cut' process to generate defects that can be used to cleave thin wafers (Romani and Evans, Nucl. Instrum. Methods Phys. Res. B 44, 313–317 (1990)). However, the implantation damage resulting from H+implantations is not completely understood. In this study, protons with energies from 400 keV up to 4 MeV and doses up to 1016 H+/cm² were implanted into highly ohmic boron doped m:Cz silicon (100). Electron Beam Induced Current (EBIC) measurements were performed to locally determine the minority charge carrier diffusion length. The diffusion length decreases with increasing implantation dose and incorporated damage. Spreading Resistance Profiling (SRP) measurements were performed to analyze the charge carrier concentration profiles for different annealing procedures. The electrical activation and growth of the defect complexes varies strongly with the annealing parameters. Transmission Electron Microscopy measurements were made to investigate the microscopic structures formed by the high dose implantation processes. Due to the high local damage density resulting from low energy and high dose H+ implants, platelet structures are formed. During high‐energy high‐dose H+implantations, the implanted hydrogen generates strain in the crystal lattice resulting in changes in the distances between atomic planes. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-08-08T04:40:06.968116-05:
      DOI: 10.1002/pssc.201400051
  • Depletion of superjunction power MOSFETs visualized by electron beam
           induced current and voltage contrast measurements
    • Authors: Stefan Kirnstoetter; Martin Faccinelli, Moriz Jelinek, Werner Schustereder, Johannes G. Laven, Hans‐Joachim Schulze, Peter Hadley
      Pages: n/a - n/a
      Abstract: Electron Beam Induced Current (EBIC) measurements were used to produce cross sectional images of superjunction power transistors. These images show how the depletion width expands under reverse bias. Superjunctions are alternating p‐ and n‐type doped vertical columns placed between drain and source in a power transistor (Deboy et al., in: Proc. IEDM, 983–685 (1998); Lorenz et al., in: Proc. PCIM Europe, 250–258 (1998)). These columns allow a higher substrate doping of the drift region, resulting in a lower on‐state resistance while still maintaining a high breakdown voltage. When the device is reverse biased, the space charge region of the superjunction should expand symmetrically due to the homogeneous doping (in the n and p region) until the complete device depletes. The depletion process was also visualized using voltage contrast (VC) measurements. Here the secondary electron signal was detected when the device was reverse biased. We show that EBIC and VC measurements can provide valuable input for process tuning and process simulations, enabling the use of smaller dimensions and higher doping levels
      PubDate: 2014-08-08T04:30:06.467238-05:
      DOI: 10.1002/pssc.201400050
  • An EBIC and SRP study on thermal donors in proton implanted p‐type
           magnetic Czochralski silicon
    • Authors: Martin Faccinelli; Stefan Kirnstoetter, Werner Schustereder, Johannes G. Laven, Peter Hadley
      Pages: n/a - n/a
      Abstract: The concentration of defects in silicon can be changed by ion implantations and thermal annealing steps. Some of the defects incorporated during these processes form complexes which can act as donors or acceptors and their concentration can even overcome the initial doping concentration of the material, and hence, cause an inversion of the doping type. One way to introduce defects and also to catalyse the formation of defect complexes is by proton implantation. For our project, a high resistivity p‐type magnetic Czochralski (m:Cz) grown silicon wafer was implanted with 4 MeV protons at an implantation dose of 2 ×1014 cm–2. The wafer was broken into pieces and these pieces were annealed at different temperatures resulting in different concentrations of defect complexes. The defects were investigated in the proton implanted region and in the substrate region beyond the penetration depth of the protons (where only the heat treatment caused a change in the defect concentrations). The local doping type and the relative change of the minority carrier diffusion length were measured using Electron Beam Induced Current (EBIC). Furthermore, resistivity profiles were measured using Spreading Resistance Profiling (SRP). The results show several changes of the doping type, the minority carrier diffusion length and the resistivity profile. In addition to donor complexes already reported in the literature, the formation of additional high temperature donor complexes has been observed. The data shows that the presence of hydrogen in silicon has a far higher influence on the changes of the electrical properties of the material at annealing temperatures between 400 °C and 510 °C than at higher annealing temperatures. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-08-08T04:30:05.270823-05:
      DOI: 10.1002/pssc.201400045
  • Electron beam silicon purification
    • Authors: Anatoly Kravtsov; Alexey Kravtsov
      Pages: n/a - n/a
      Abstract: Purification of heavily doped electronic grade silicon by evaporation of N‐type impurities with electron beam heating was investigated in process with a batch weight up to 50 kilos. Effective temperature of the melt, an indicative parameter suitable for purification process characterization was calculated and appeared to be stable for different load weight processes. Purified material was successfully approbated in standard CZ processes of three different companies. Each company used its standard process and obtained CZ monocrystals applicable for photovoltaic application. These facts enable process to be successfully scaled up to commercial volumes (150‐300 kg) and yield solar grade silicon. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-08-08T04:23:33.625363-05:
      DOI: 10.1002/pssc.201400031
  • Determination of the single crystal Ge Young’s modulus between room
           temperature and melting temperature using the impulse excitation technique
    • Authors: Akhilesh K. Swarnakar; Omer Van der Biest, Jan Van Humbeeck, Jan Vanhellemont
      Pages: n/a - n/a
      Abstract: In the present study, the vibrational properties of single crystal Ge samples are studied between room and melt‐ing temperature using the impulse excitation technique (IET). From the IET measurements, the temperature dependent Young's moduli Eijk of single crystal Ge are extracted in the (100), (110) and (111) crystallographic directions in inert atmosphere. The results show an anomalous softening of an elastic constant around 890 °C temperature during the measure‐ment. The Young's moduli values between 88 to 132 GPa are obtained close to the melting temperature, depending on the crystallographic direction. Empiric expressions are derived for the temperature dependence of E(100), E(110) and E(111). (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-08-08T04:20:05.544496-05:
      DOI: 10.1002/pssc.201400011
  • Photoluminescence properties of Ce3+ ions in Ce‐doped SiO1.5 thin
           films containing Si nanocrystals
    • Authors: J. Weimmerskirch‐Aubatin; M. Stoffel, X. Devaux, A. Bouché, M. Vergnat, H. Rinnert
      Pages: n/a - n/a
      Abstract: We investigate the luminescence properties of Ce3+ ions in Ce‐doped SiO1.5 thin films containing Si nanocrystals (Si‐ncs) by means of steady‐state photoluminescence (PL), time‐resolved PL and PL excitation spectroscopy. Strong Ce‐related blue luminescence is observed with the naked eye at room temperature. The Ce‐related lumines‐cence is found to ncrease with the Ce content in the films while simultaneously, the Si‐nc‐related luminescence decreases. Moreover, the decay time of the Si‐nc related luminescence decreases for increasing Ce concentrations thus suggesting a possible indirect excitation of the Ce3+ ions via Si‐ncs. However, PL excitation measurements show that Ce3+ ions are mainly directly excited with only a negligible influence of the Si‐ncs. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-07-25T05:10:14.445674-05:
      DOI: 10.1002/pssc.201400042
  • Tuning optical a‐SiC/a‐Si active filters by UV bias light in
           the visible and infrared spectral ranges
    • Authors: M. Vieira; M. A. Vieira, I. Rodrigues, V. Silva, P. Louro
      Pages: n/a - n/a
      Abstract: Visible range to telecom band spectral translation is accomplished using an amorphous SiC pi'n/pin wavelength selector under appropriate front and back optical light bias. Results show that background intensity works as selectors in the infrared region, shifting the sensor sensitivity. Low intensities select the near‐infrared range while high intensities select the visible part according to its wavelength. Here, the optical gain is very high in the infrared/red range, decreases in the green range, stays close to one in the blue region and strongly decreases in the near‐UV range. The transfer characteristics effects due to changes in steady state light intensity and wavelength backgrounds are presented. The relationship between the optical inputs and the output signal is established. A capacitive optoelectronic model is presented and tested using the experimental results. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-07-25T05:10:13.125023-05:
      DOI: 10.1002/pssc.201400020
  • Comparison between experimental and simulated strain profiles in Ge
           channels with embedded source/drain stressors
    • Authors: R. Bühler; G. Eneman, P. Favia, H. Bender, B. Vincent, A. Hikavyy, R. Loo, J. A. Martino, C. Claeys, E. Simoen, N. Collaert, A. Thean
      Pages: n/a - n/a
      Abstract: Two planar Ge‐based MOSFET structures were analysed for n‐ and p‐type transistors with tensile and compressive strain implemented in the channel direction using source/drain stressors. Strain profiles measured by nano‐beam diffraction (NBD) have been compared with Sentaurus process simulations. The TCAD simulations were tuned with the actual process using NBD measurements, resulting in a more realistic simulation and, therefore, a more reliable interpretation is now possible. dark‐field scanning transmission electron microscopy images added to the strain profiles returned interesting results about the Ge virtual substrate condition and how it disturbs the NBD readings due to the presence of extended defects in strain relaxed Ge buffer layers. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-07-25T05:10:12.035703-05:
      DOI: 10.1002/pssc.201400021
  • Mediation effect of sub‐monolayer carbon on interfacial mixing in Ge
           growth on Si(100)
    • Authors: Yuhki Itoh; Ryo Hayase, Shinji Hatakeyama, Tomoyuki Kawashima, Katsuyoshi Washio
      Pages: n/a - n/a
      Abstract: The mediation effect of carbon (C) on interfacial mixing in Ge growth was studied using C‐covered Si surface (Ge/C/Si) and C over thin Ge buffer layer (Ge/C/Ge/Si) systems. The samples were prepared by solid‐source molecular beam epitaxy system with electron beam gun for C sublimation and K‐cell for Ge evaporation. The interdiffusion at the interface and deterioration in crystallinity of Ge layer was evaluated by Raman spectroscopy and X‐ray diffraction, respectively. In the case of Ge/C/Si system, the interdiffusion of Si and Ge atoms was suppressed by more than 0.3 monolayer (ML)‐C depositions while crystallinity of Ge layer was deteriorates by the formation of Si‐C at the Si surface and the incorporation of C atoms in Ge layer. In the case of Ge/C/Ge/Si system, the crystallinity of Ge layer was maintained even at C coverage of a few MLs, however, the amount of C to suppress the Ge/Si interdiffusion was more than 3 ML. From the correlation between Ge crystallinity and surface roughness, Ge/C/Ge/Si structure is considered to be more effective to take advantage of C mediation. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-07-25T05:10:11.101235-05:
      DOI: 10.1002/pssc.201400032
  • Viability of the use of an a‐SiC:H multilayer device in a domestic
           VLC application
    • Authors: P. Louro; V. Silva, M. A. Vieira, M. Vieira
      Pages: n/a - n/a
      Abstract: In this paper the viability of an integrated wavelength optical filter and photodetector for visible light communication (VLC) is discussed. The proposed application uses indoor warm light lamps lighting accomplished by ultra‐bright light‐emitting diodes (LEDs) pulsed at frequencies higher than the ones perceived by the human eye. The system was analyzed at two different wavelengths in the visible spectrum (430 nm and 626 nm) with variable optical intensities. The signals were transmitted into free space and measured using a multilayered photodetector based on a‐SiC:H/a‐Si:H. The detector works as an optical filter with controlled wavelength sensitivity through the use of optical bias. The output photocurrent was measured for different optical intensities of the transmitted optical signal and the extent of each signal was tested. The influence of environmental fluorescent lighting was also analysed in order to test the strength of the system. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-07-25T05:10:10.256382-05:
      DOI: 10.1002/pssc.201400035
  • Enhancement of IR photoluminescence of β‐FeSi2 nanocrystals by
           Cu‐doping and study of its mechanism
    • Authors: Yoshihito Maeda; Takahide Tatsumi, Yuki Kawakubo, Yuya Noguchi, Hiroyuki Kobayashi, Kazumasa Narumi, Seiji Sakai
      Pages: n/a - n/a
      Abstract: We have investigated the IR photoluminescence (PL) behavior of Cu‐doped β‐FeSi2 nanocrystals (β‐NCs) embedded in Si layers. The diffusion rate of Cu atom was controlled by annealing. The most appropriate condition brought the largest intensities of both the intrinsic A band emission at 0.803 eV by 214% and the acceptor related C band emission at ∼0.75 eV by 582% in comparison with those of non‐doped β‐NCs. Rutherford backscattering spectrometry (RBS) revealed increase of Cu atoms in the Si layer with β‐NCs with increasing the anneal duration. The C band enhancement surely is originated from increase of a density of state at acceptor levels relating to increase of Cu in β‐lattice. Photocarrier injection PL measurements (PCI‐PL) reveal that the enhancement of the A band emission may be attributed to a controlled migration process of holes with a repeated trap process due to Cu‐doping into the Si phase. This dynamic condition leads to an increase of valence band offset at the β‐NCs/Si heterointerfaces where the migration of holes from the β‐NCs to Si is prevented, so that a radiative recombination rate can be enhanced. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-07-25T05:10:09.416628-05:
      DOI: 10.1002/pssc.201400039
  • Raman analysis of gold catalyst vapor liquid solid germanium nanowires
    • Authors: M. Israel; A. Moreac, R. Rogel, J. P. Landesman, L. Pichon
      Pages: n/a - n/a
      Abstract: Germanium nanowires (GeNWs) were synthesized in a low pressure chemical vapor deposition reactor (LPCVD) using a vapor‐liquid‐solid process (VLS). In this work, the focus is put on the characterization of these GeNWs using scanning electron microscopy (SEM) combined with Raman spectroscopy. In particular, NWs with conical shape grown at a moderate temperature (320 °C) were investigated in terms of the intensity measured for the Ge‐related Raman line. The two main observations, discussed in this paper, are the anomalous magnitude of this line, as compared to measurements under the same conditions on a Ge(100) substrate, and the oscillations observed when the Raman line intensity is measured while scanning the laser beam along the axis of the conical shaped NWs, from the tip to the bottom. These effects are discussed involving the fact that optical modes appear in such NWs (both for the incident and Raman scattered light) when conditions on the diameter, the laser excitation wavelength, and substrate (on which the NWs are transferred after growth) are fulfilled. Taking into account these specific optical modes, the effects observed can be explained. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-07-25T05:10:08.278128-05:
      DOI: 10.1002/pssc.201400041
  • Modeling and multifractal analysis of radiation defect evolution in solids
    • Authors: Kazbek Baktybekov; Aliya Baratova
      Pages: n/a - n/a
      Abstract: The results of modeling of radiation defects formation and evolution on the surface and in the volume of a crystal are presented in this paper. Statistical properties are calculated for the investigated system. It is revealed that defect structure is a multifractal and system entropy decreases, while observing self‐organization of the physical system. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-05-20T07:23:11.964285-05:
      DOI: 10.1002/pssc.201400005
  • Contents: Phys. Status Solidi C 1–12/2014
    • Pages: 1539 - 1543
      PubDate: 2014-11-21T10:35:38.995509-05:
      DOI: 10.1002/pssc.201470065
  • Materials Research for Group IV Semiconductors
    • Authors: Sergio; Pizzini, Gudrun Kissinger
      Pages: 1544 - 1544
      Abstract: This volume is a collection of papers presented at Symposium X “Materials Research for Group IV Semiconductors: Growth, Characterization, and Technological Developments” at the E‐MRS Spring Meeting 2014 held from May 26–30 in Lille, France. Different from the recent past, the major challenges for fundamental research and technological development in microelectronics and photovoltaics are no more confined to bulk silicon and silicon devices but to a variety of options based on silicon alloys, nanocrystalline silicon, silicon nanowires, Ge films on silicon, and graphene. Group IV elements are dominating microelectronics, photovoltaics, and nano‐technology in their whole variety and with ongoing innovation potential. The overall development is driven more and more by defect engineering procedures, optimized deposition processes and growth techniques, advanced diagnostics and modeling tools. Basic research on point defects and extended defects remains in the center of interest for both electronic and photovoltaic applications, being still important for solving defect related problems, for improved defect engineering, and to increase the efficiency of gettering processes in photovoltaic and electronic materials. Crystal growth for electronic applications moves towards 450 mm diameter silicon ingots while photovoltaic applications are seeking a tradeoff between high quality of large volumes and cost efficiency. Advanced float‐zone processes open new opportunities, and modeling of crystal growth and defect generation for Si, Ge and Si–Ge alloys can help to facilitate these developments. Optimization of epitaxial deposition of nitrides on silicon substrates as well as novel methods for the growth of graphene on silicon are in the center of interest because of their innovation potential for the optoelectronic and microelectronic industry. Selective epitaxy for advanced electronic applications and strain engineering in strained layer epitaxy are still important for the heterogeneous integration of Si or Ge in high‐end silicon device technologies. Eventually, nanocrystalline group IV semiconductors in their whole variety from quantum dots, nanowires and superlattices offer a number of novel opportunities for new applications in view of “more than Moore”. The symposium addressed its interest to all these topics and provided a successful forum for scientists coming from research institutions and industry of Asia, America, Australia, Africa, and Europe to discuss recent results and developments in materials research on group IV elements. In total, 72 oral and 113 poster presentations have made this symposium a fruitful expert meeting, with mutual benefits arising from technical and scientific interactions between academy and industry. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2014-11-21T10:35:43.764053-05:
      DOI: 10.1002/pssc.201470066
  • Numerical analysis of light elements transport in a unidirectional
           solidification furnace
    • Authors: Koichi Kakimoto; Bing Gao, Satoshi Nakano
      Pages: n/a - n/a
      Abstract: Quantitative study of light elements such as carbon and oxygen in multi‐crystalline silicon for solar cells is required to grow crystals with high quality. The transport of both carbon and oxygen is one of the critical issues to increase efficiency of solar cells made of silicon materials. Concentrations of carbon and oxygen in a furnace affect each others, therefore it is important to control mass transfer of carbon and oxygen in a furnace. Numerical calculation with a chemical reaction between carbon and oxygen was carried out to study how both light impurities are incorporated into crystals through the melt and gas during solidification process. The effects of flow rate and pressure on the impurities were examined. An increase in the flow rate can reduce both carbon and oxygen impurities in the crystal, though the reduction of carbon is more obvious. An increase in gas pressure can also obviously reduce the oxygen impurity but has only a small effect on the carbon impurity (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2010-11-15T04:22:05.648279-05:
      DOI: 10.1002/pssc.200900117
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