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 physica status solidi (c)   [SJR: 0.471]   [H-I: 31]   [1 followers]  Follow         Hybrid journal (It can contain Open Access articles)    ISSN (Print) 1862-6351 - ISSN (Online) 1610-1642    Published by John Wiley and Sons  [1598 journals]
• Issue Information: Phys. Status Solidi C 7–9/2016
• PubDate: 2016-07-26T05:23:35.72582-05:0
DOI: 10.1002/pssc.201670129

• Cover Picture: Phys. Status Solidi C 7–9/2016
• Abstract: In this work, polycrystalline n‐doped ZnO layers and n‐doped ZnO nanowires are coated with the p‐doped organic polymers polypyrrole and PEDOT by using oxidative chemical vapor deposition (oCVD). The goal of S. Bley and coworkers (pp. 614–617) is to form hybrid hetero‐junctions for developing efficient and low‐cost optoelectronic devices for applications such as LEDs and solar cells, and to show that oCVD is a versatile technique for the fabrication of inorganic/organic core–shell structures. The structural, electrical, and optical properties of polymer‐coated ZnO structures have been investigated by SEM, TSEM, EDX, electrical, and PL measurements. SEM and electrical measurements on the polypyrrole‐coated ZnO layers show that a de‐creasing amount of the used oxidizing agent (FeCl3) from 0.3 g to 0.1 g leads to thin and homogeneous coating which increases the quality of the formed pn‐heterojunction. Structural and optical investigations of the coated ZnO nanowires show that a thin and conformal polymer coating of the nanowires is achieved by using 0.1 g FeCl3 without affecting the general optical properties of ZnO. Cl doping of the polymer shell is confirmed by EDX measurements.
PubDate: 2016-07-26T05:23:30.557459-05:
DOI: 10.1002/pssc.201670128

• Electrical characterization of MIS structures with HfOx gate dielectric
films fabricated on silicon substrates modified by ultra‐shallow ion
implantation from RF plasma
• Abstract: The feasibility of ultra‐shallow fluorine and nitrogen implantation from RF plasma into silicon substrates, and the correlation between implantation process parameters, and electro‐physical properties of obtained Metal‐Insulator‐Semiconductor (MIS) structures with hafnium oxide (HfOx) layer as a gate dielectric was investigated. The analysis of electrical characteristics of MIS structures proved that almost all fabricated structures after plasma implantation are characterized by lower flat‐band voltage (Ufb) value (in absolute values) and lower effective charge (Qeff) in comparison to reference samples. However, the limitation of such an improvement is the specified value of power applied to the reactive chamber (i.e., 120 W). MIS structures are also characterized by a lower leakage current and very significant increase in the breakdown voltage (Ubr) value. The structural characterization has demonstrated that both types of plasma implantation result in the introduction of the relatively high concentration of fluorine and nitrogen into silicon subsurface area. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-07-19T07:30:06.557295-05:
DOI: 10.1002/pssc.201600061

• Stress relaxation mechanism in the Si‐SiO2 system and its influence
on the interface properties
• Authors: Daniel Kropman; Viktor Seeman, Sergei Dolgov, Ivo Heinmaa, Artur Medvid
Abstract: The results of the investigation of stress relaxation by strain by means of EPR spectra, IR absorption spectra, SEM and samples deflection are presented. It has been shown that stress relaxation mechanisms depend on the oxidation conditions: temperature, cooling rate, oxide thickness. In the Si‐ SiO2‐Si3N4 system the stress relaxation by strain occur due to the opposite sign of the thermal expansion coefficient of Si‐SiO2 and Si3N4 on Si. Laser irradiation allows to modify the system stresses. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-07-19T07:30:05.706696-05:
DOI: 10.1002/pssc.201600051

• Simulation of the proton implantation process in silicon
• Abstract: Proton implantation is one of many processes used to ad‐just the electronic and mechanical properties of silicon. Though the process has been extensively studied, it is still not clear which exact defects are formed and what their concentration profiles are. In this article, a simulation method is presented, which provides a better understanding of the implantation process. The simulation takes into account the diffusion of mobile point defects and their reactions to defect complexes, as well as the dissociation of defect complexes. Concentration profiles for a set of defect complexes after an implantation at 400 keV and a dose of 5 × 1014 H+cm−2 are presented. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-07-19T07:30:04.549686-05:
DOI: 10.1002/pssc.201600038

• Grain boundary effect on lifetime in high performance multicrystalline
silicon during solar cell processing
• Abstract: High performance multicrystalline silicon wafers used in solar cell processing have been investigated with focus on quantification of the grain boundary effect on lifetime. The lifetime of a set of 16 wafers from different positions along the ingot and after different process steps – phosphorus gettering, SiNx:H layer deposition and firing – is measured by µPCD and compared with microstructural information from EBSD. This allows for analysis of the behaviour of grain boundaries and their influence on lifetime during solar cell processing. The minority carrier lifetime of HPMC‐Si wafers is not increased after the gettering step, but even reduced for some samples. It is shown that the lifetime in areas close to grain boundaries is reduced during the gettering step and this has a stronger effect on the average value than the improvement within the grains. Only wafers after both gettering and hydrogenation show an overall improvement in carrier lifetimes. However, in the regions close to the bottom of the ingot, wafers show lifetime degradation after the hydrogenation process. The results are used to obtain quantitative information on recombination velocity of grain boundaries. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-07-11T04:50:08.153198-05:
DOI: 10.1002/pssc.201600059

• Investigation of different cases of dislocation generation during
industrial Cz silicon pulling
• Abstract: This study aims at better understanding the generation of dislocations causing a structure loss issue during the pulling of Czochralski silicon ingots. Several industrial‐scale n‐type ingots containing this issue were characterized. The generation and propagation of dislocations were observed in each ingot along with an investigation of the perturbation at the origin of the structure loss. The results show that for the two ingots characterized in this study, particles entering in contact with the ingot edge during crystal growth are responsible for the generation of dislocations. Moreover, the propagation of dislocations was compared for two different structure loss origins: particles in contact with the ingot edge and the crystallization around a gas bubble (pinhole) in the middle of the ingot. In each case, a fast transition between the original dislocation‐free growth and a growth with dislocations was observed at the perturbation position. Differences in the propagation of slip dislocations backward in the crystal are discussed as well as differences in the transition to a multicrystalline silicon growth regime. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-07-11T04:50:07.130943-05:
DOI: 10.1002/pssc.201600063

• Capacitance‐voltage spectroscopy and analysis of dielectric
intrinsic amorphous silicon thin films
• Authors: Sebastian Gerke; Gabriel Micard, Reinhart Job, Giso Hahn, Barbara Terheiden
Abstract: Capacitance‐voltage (CV) spectroscopy of classic metal‐insulator‐semiconductors (MIS) using insulating oxides as well as highly passivating intrinsic and hydrogenated amorphous silicon ((i) a‐Si:H) has been discussed extensively in literature, particularly with regard to photovoltaic applications. Imperfectly passivating as well as thermal or light‐induced degraded (i) a‐Si:H exhibits a reduced passivation quality and an increased defect‐based shunt conductivity. These properties cannot be accounted for by classical CV spectroscopy as described in literature for insulating oxides or highly passivating (i) a‐Si:H. To characterize such imperfectly passivating or degraded (i) a‐Si:H thin films by CV spectroscopy, the required MIS samples have to be prepared following special design rules. Design rules were defined on the base of electric field FEM investigations and empirically validated. In combination with an adapted approach to calculate the number of defects (ND) CV spectrometry becomes a more reliable analytic tool to describe imperfectly passivating as well as degraded (i) a‐Si:H. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-07-11T04:40:15.607232-05:
DOI: 10.1002/pssc.201600019

• Detection and reduction of tungsten contamination in ion implantation
processes
• Authors: M. L. Polignano; A. Galbiati, S. Grasso, I. Mica, F. Barbarossa, D. Magni
Abstract: In this paper, we review the results of some studies addressing the problem of tungsten contamination in implantation processes. For some tests, the implanter was contaminated by implantation of wafers with an exposed tungsten layer, resulting in critical contamination conditions. First, DLTS (deep level transient spectroscopy) measurements were calibrated to measure tungsten contamination in ion‐implanted samples. DLTS measurements of tungsten‐implanted samples showed that the tungsten concentration increases linearly with the dose up to a rather low dose (5×1010 cm–2). Tungsten deactivation was observed when the dose was further increased. Under these conditions, ToF‐SIMS revealed tungsten at the wafer surface, showing that deactivation was due to surface segregation. DLTS calibration could therefore be obtained in the linear dose regime only. This calibration was used to evaluate the tungsten contamination in arsenic implantations. Ordinary operating conditions and critical contamination conditions of the equipment were compared. A moderate tungsten contamination was observed in samples implanted under ordinary operating conditions. This contamination was easily suppressed by a thin screen oxide. On the contrary, implantations in critical conditions of the equipment resulted in a relevant tungsten contamination, which could be reduced but not suppressed even by a relatively thick screen oxide (up to 150 Å). A decontamination process consisting of high dose implantations of dummy wafers was tested for its efficiency to remove tungsten and titanium contamination. This process was found to be much more effective for titanium than for tungsten. Finally, DLTS proved to be much more sensitive that TXRF (total reflection X‐ray fluorescence) in detecting tungsten contamination. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-07-11T04:40:14.491906-05:
DOI: 10.1002/pssc.201600022

• A statistical model for the gettering of impurities on an atomistic scale
• Authors: Eiji Kamiyama; Koji Sueoka, Jan Vanhellemont
Abstract: The phenomena of impurities in Si in thermal equilibrium can be described on an atomistic scale. This model can statistically estimate the thermal equilibrium concentrations and the distribution of any metallic contamination atoms in advanced wafer structures if the gettering site densities in the wafer and their binding energies for the metallic impurity atoms are known. This model has the advantage that gettering phenomena can be calculated based on ab initio calculation results. Ab initio calculations indeed allow calculating the binding energy of any kind of contamination atom at any position in crystals without the need to perform extensive experiments. The model is illustrated for the gettering of Cu atoms in a p‐type Si double layer structure consisting of a moderately B‐doped layer, the “device layer,” and a heavily B‐doped layer, the “substrate.” By using this statistical approach, we can also predict Cu solubility in Si wafers for various B‐doping levels without the assumption of any solubility data in a previously‐known doping level, as is typically found in the literature. The calculated results show good agreement with published experimental observations. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-07-11T04:40:13.64033-05:0
DOI: 10.1002/pssc.201600031

• Reduced oxygen precipitation in heavily arsenic‐doped
Cz‐silicon crystals
• Authors: M. Porrini; S. Haringer, A. Giannattasio
Abstract: Oxygen precipitation in heavily arsenic doped Czochralski silicon is investigated for a wide dopant concentration range (from 3 × 1018 cm–3 to 4 × 1019 cm–3) and it is compared with that observed in lightly doped silicon having similar initial oxygen concentration. A lower density of oxide precipitates after an anneal of 4 h at 800 °C followed by 16 h at 1000 °C is measured in the case of arsenic doped samples, in comparison to lightly doped ones, when the dopant concentration exceeds 1.6 × 1019 cm–3. In addition, no radial bands (rings) of precipitation are observed in arsenic‐doped samples, contrary to lightly doped samples grown at the same V/G (ratio between pull rate V and axial thermal gradient G). These findings are explained by considering the role played by vacancies in the formation of oxygen precipitates and the impact of the arsenic concentration on the total concentration of point defects in silicon. Data obtained by computer simulation of microdefect formation in silicon are also presented in support of this explanation. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-07-11T04:40:12.898534-05:
DOI: 10.1002/pssc.201600045

• Identification of carbon‐hydrogen complexes in n‐ and
p‐type silicon
• Abstract: The origin of several deep traps E42, E90, E262, and H180 in hydrogenated n ‐type and p ‐type FZ and CZ Si is investigated. Comparing the depth profiles of these defects in samples with different C, O, H, and shallow donor (acceptor) concentrations we conclude that they belong to carbon‐hydrogen‐related defects consisting of one C and one H atom. The similar annealing behavior and identical depth profiles of E42 and E262 correlate them with two different charge states of the same defect. From a comparison with earlier calculations we attribute E42 to the double acceptor and E262 to the single acceptor state of the CH1AB complex. In good agreement with the results of previous studies E90 is assigned to the acceptor state of the CH1BC complex. Our preliminary Laplace DLTS studies on SiGe with a Ge content
PubDate: 2016-07-11T04:40:12.097938-05:
DOI: 10.1002/pssc.201600046

• On the use of hopping conduction for the determination of dopant
concentration in compensated silicon
• Abstract: This work explores the possibility to use the mechanism of hopping conduction – and particularly the transition temperature between band and hopping conduction – on low temperature resistivity measurements, for the control of dopants densities in p‐type compensated silicon. This work first establishes a parametric study of the hopping conductivity: the impact of the majority dopant density and of the compensation ratio is investigated. In the range of majority dopant concentration studied (5×1016 cm–3–5×1017 cm–3), a linear relation seems to appear between the majority dopant concentration and the transition temperature, and this, apparently whatever the compensation impurity type or the crystalline structure. It was then shown that both minority and majority dopant densities can be estimated from a single resistivity versus temperature curve. To our knowledge, this work presents the first experimental study of the feasibility of using such mechanisms to collect relevant information on the compensated Si composition. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-07-11T04:40:11.242703-05:
DOI: 10.1002/pssc.201600048

• Wafering of ultra‐thin silicon substrates by MeV hydrogen
implantation: effects of fluence and energy
• Abstract: In this paper, we report on implantation parameters allowing the delamination of large surface of ultra‐thin silicon substrates by using MeV hydrogen implantation. We particularly focus on the effects of both hydrogen fluence and implantation energy, on the size of the largest delaminated surface in one piece. We demonstrate that thin silicon substrates with thicknesses between 30 µm and 70 µm can be extracted from silicon commercial wafers. In this study, the used‐material, the implantation energy and the hydrogen fluence ranges are (100) Si, 1.5 MeV‐2.5 MeV, 1×1017cm–2‐2×1017cm–2, respectively. We find that, by increasing hydrogen fluence, the maximum achievable surface of delaminated substrates in one piece can be doubled. Indeed, by XTEM, we observed that fracture precursor defects are mostly oriented along {111} in the case of the lowest fluence, which are unfavorable for a good surface‐parallel crack propagation. For the highest fluence, precursors are oriented along {100} which are parallel to the substrate surface, therefore they allow propagation over longer distances of cracks parallel to the substrate surface. We also find that, despite of the raise of the proportion of precursors oriented along {111}, the total surface of delaminated substrates significantly increases with the implantation energy. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-07-11T04:40:10.369794-05:
DOI: 10.1002/pssc.201600054

• A novel kerf‐free wafering process combining stress‐induced
spalling and low energy hydrogen implantation
• Abstract: In this work, we studied the potential use of low‐energy hydrogen implantation as a guide for the stress‐induced cleavage. Low‐energy, high fluence hydrogen implantation in silicon leads, in the right stiffening conditions, to the detachment of a thin layer, around a few hundreds nm thick, of monocrystalline silicon. We implanted monocrystalline silicon wafers with low‐energy hydrogen, and then glued them on a cheap metal layer. Upon cooling down, the stress induced by the stressor layers (hardened glue and metal) leads to the detachment of a thin silicon layer, which thickness is determined by the implantation energy. We were then able to clearly demonstrate that, as expected, hydrogen oversaturation layer is very efficient to guide the stress. Using such process, thin silicon layers of around 710 nm‐thick were successfully detached from low‐energy implanted silicon wafers. Such layers can be used for the growth of very good quality monocrystalline silicon of around 50 µm‐thick or less. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-07-11T04:40:09.487809-05:
DOI: 10.1002/pssc.201600056

• Effects of substrate temperature on change in percolation properties of
ultra thin dielectric films
• Abstract: In this paper, we explored the impact of surface roughness on ultra‐thin dielectrics characteristics. Simple cubic lattice is used as a base for depositing spheres of radius R, designed as a thin film, as the base for simulation of defects generation and deposition. Continuum percolation model, used to generate a rough surface in order to analyse how roughness and temperature influence the conductivity, consists of randomly placed spheres of either one or some distribution of radii, which then form a thin, rough layer in question. It is shown that when the temperature of the substrate is increased material defects tend to form within the film contributing to a faster cluster growth and greater film conductivity. The influence of temperature on average cluster size for homogeneous distribution of defects is assumed according to the applied temperature (depending on the free carrier's diffusion length) is researched. It is evident from the performed simulations that temperature has an important influence on thin film conductivity in several different ways; it can contribute to the increase of the number of spanning clusters or the average size of clusters. This way, defects can either provide starting points for new spanning clusters or can encourage clusters merging. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-06-03T03:10:10.670256-05:
DOI: 10.1002/pssc.201610041

• Deposition of a‐Si:H thin films using tailored voltage waveform
plasmas: impact on microstructure and stability
• Authors: Junkang Wang; Christophe Longeaud, Federico Ventosinos, Dmitri Daineka, Mustapha El Yaakoubi, Erik V. Johnson
Abstract: Exciting processing plasmas using non‐sinusoidal, “Tailored” voltage waveforms (TVWs), have recently been shown to be effective to separately control the maximum ion bombardment energy (IBE) and the ion flux on each electrode in the capacitively coupled plasma (RF‐CCP) processes. In this work, we use it to deposit hydrogenated amorphous silicon (a‐Si:H) thin films from hydrogen‐diluted silane by low temperature plasma‐enhanced chemical vapor deposition. The impact of using TVWs on the material's structural and electronic properties is examined. Excessively low IBE can lead to a high Si‐H2bonded hydrogen content within the deposited films, which results in a deterioration of the material stability upon light‐soaking, detectable at a microstructure level. A low content of hydrogen bonded in a Si‐H2configuration and a low sub‐gap density of states was observed in the film deposited using a “sawtooth‐down” type of waveform. Such excitation also produced the a‐Si:H films with the best transport properties (majority and minority carrier μτ‐products and the ambipolar diffusion length) and stability under light‐soaking. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-06-03T03:10:09.73298-05:0
DOI: 10.1002/pssc.201600024

• Jan Vanhellemont – 35 years of materials research in
microelectronics
• Abstract: On the occasion of the decease of Prof. Jan Vanhellemont, a brief overview of his scientific career, covering more than 35 years in semiconductor materials science, is given in this paper. The main scientific highlights are summarized. Besides the different positions he has taken in his career at different universities and companies, he has also been very active in establishing a world‐wide network of collaborations and contacts, who often became also good friends. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-06-03T03:10:08.529745-05:
DOI: 10.1002/pssc.201600023

• High performance InGaZnO‐based Schottky diodes fabricated at room
temperature
• Authors: Linlong Yan; Qian Xin, Lulu Du, Jiawei Zhang, Yi Luo, Qingpu Wang, Aimin Song
Abstract: Recently, Indium gallium zinc oxide (InGaZnO or IGZO) has attracted much attention for flexible and transparent electronics, because of its superior electric properties, optical transparency and low processing temperature. In this work, Schottky diodes with a structure of Pd/IGZO/Ti/Au were fabricated by radio‐frequency magnetron sputtering at room temperature without any thermal treatment. The optimised diode with a 66‐nm‐IGZO layer shows an extremely large barrier height (1.02 eV), a very high rectification ratio (> 8.5 × 107), and a close to unit ideality factor (1.23). Our results suggest that Pd and IGZO can form very high quality Schottky contact with a large barrier height, extremely low defects density and high uniformity. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-06-03T03:10:07.432455-05:
DOI: 10.1002/pssc.201510291

• HgCdTe p+‐n structures grown by MBE on Si (013) substrates for high
operating temperature SWIR detectors
• Authors: V. M. Bazovkin; S. A. Dvoretskiy, A. A. Guzev, A. P. Kovchavtsev, D. V. Marin, Z. V. Panova, I. V. Sabinina, Yu. G. Sidorov, G. Yu. Sidorov, A. V. Tsarenko, V. S. Varavin, V. V. Vasiliev, M. V. Yakushev
Abstract: Electrophysical properties of multilayered heteroepitaxial structures of Hg1‐xCdxTe with x=0.3‐0.4 grown by molecular beam epitaxy on silicon substrates are presented. The passivating effect of thin CdTe layers grown on top of the structures in single process is demonstrated. Comparison between experimental and theoretical temperature dependencies of reverse currents in n‐on‐p and p‐on‐n diodes fabricated by boron and arsenic ion implantation in vacancy‐doped p‐type and In‐doped n‐type Hg1‐xCdxTe films, respectively, are presented. The influence of p‐n junction position in double‐layer heterostructure on temperature dependencies of reverse currents is examined. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-05-13T06:30:15.827321-05:
DOI: 10.1002/pssc.201510259

• ZnSe:Mn aqueous colloidal quantum dots for optical and biomedical
applications
• Authors: Thiago G. Silva; Igor M. R. Moura, Paulo E. Cabral Filho, Maria I. A. Pereira, Clayton A. Azevedo Filho, Goreti Pereira, Giovannia A. L. Pereira, Adriana Fontes, Beate S. Santos
Abstract: In this study, we present the optimization of the optical properties of Mn2+ doped ZnSe QDs (also referred to as d‐dots) coated with thioglycolic acid in aqueous medium. The nanoparticles were characterized by ionic coupled plasma, electron paramagnetic resonance, transmission electron microscopy and X‐ray diffractometry. By applying a controlled dose of UV irradiation, we obtained efficient orange emitting d‐dots (4T1→ 6A1 transition centered at 580 nm). The results point out to a doping fraction in the nanoparticles smaller than 1% (0.89%), and that the Mn2+ ions are preferentially located close to the particle's surface. The UV photoactivation procedure has a definite influence on the emission intensity and on the colloidal stability of the particles. Photoactivated Mn2+ d‐dots were conjugated to Concanavalin A and labeled specifically Candida albicans yeast cells, by targeting carbohydrate residues depicting the successful use of these QDs as fluorescent probes. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-05-13T06:30:14.725451-05:
DOI: 10.1002/pssc.201510300

• Authors: Vladimir Voronkov; Robert Falster
Abstract: Light‐induced degradation of minority carrier lifetime in silicon is caused by the formation of two B‐O recombination centres: fast‐stage centres (FRC) and slow‐stage centres (SRC). FRC were concluded to emerge by a carrier‐assisted reconfiguration of a latent BO2 defect composed of a substitutional boron atom and an oxygen dimer. The nature of SRC however remained uncertain; this defect appeared to involve an interstitial boron atom rather than a substitutional one. More recent data on SRC in boron‐containing compensated p‐Si and n‐Si now show that the SRC actually emerge in the same way as FRC: by a reconfiguration of BO2, but from a different latent form. The two latent BO2 defects (the precursors for FRC and for SRC) are created during a cooling stage after the last high‐temperature anneal, and their concentration, proportional to the boron concentration and squared oxygen concentration, depends on the cooling rate. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-05-13T06:30:13.688865-05:
DOI: 10.1002/pssc.201600016

• Comparison between Si/SiO2 mid‐gap interface states and deep levels
associated with silicon‐oxygen superlattices in p‐type silicon

• Authors: Eddy Simoen; S. Jayachandran, A. Delabie, M. Caymax, M. Heyns
Abstract: In this paper, the deep levels found by deep‐level transient spectroscopy in Si‐O superlattices on p‐type silicon substrates are compared with the band of near mid‐gap hole traps typically observed at the Si/SiO2 interface. In addition, the impact of a post‐deposition Forming Gas Annealing is investigated. A large similarity between the two material systems is reported, which indicates that similar silicon‐oxygen bonds may be responsible for the deep hole traps.(© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-05-13T06:30:12.682755-05:
DOI: 10.1002/pssc.201600018

• Towards multifunctional heterostructured materials: ZnO nanowires growth
on mesoscale periodically patterned Si
• Authors: Anisha Gokarna; Agnieszka Gwiazda, Hind Kadiri, Anna Rumyantseva, Komla Nomenyo, Roy Aad, Gilles Lerondel
Abstract: We report the growth of ZnO nanowires on mesoscale periodically patterned silicon. The aim of this work is to go towards fabrication of multifunctional heterostructured materials for increasing the specific surface area and light absorption properties. ZnO nanowires (NWs) were grown by chemical bath deposition technique on patterned silicon. Silicon patterning was conducted by two methods, namely, laser interference lithography and nanosphere lithography. We have studied the structural and optical properties of the ZnO NWs grown on these silicon patterns. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-05-03T03:40:48.47202-05:0
DOI: 10.1002/pssc.201510295

• Structural, electronic and thermodynamic properties of SrxCa1‐xS: A
first‐principles study
• Authors: S. Labidi; M. Boudjendlia, M. Labidi, J. Zeroual, R. Bensalem, F. El Haj Hassan
Abstract: The principal purpose of this work is to further the understanding of the structural, electronic, and thermodynamic properties of the SrxCa1–xS alloys (0≤x ≤1) in Rock‐salt phase using the full potential augmented plane wave (FP‐LAPW) method within density functional theory. The exchange‐correlation potential for structural properties was calculated by the standard local density approximation (LDA) and GGA (PBE) and the new form of GGA (WC) which is an improved form of the most popular Perdew‐Burke‐Ernzerhof (PBE), while for electronic properties, the alternative form of GGA modified by Becke‐Johnson exchange correlation potential (MBJ) was also applied. It is shown that investigation on the effect of composition on lattice constant, bulk modulus, and band gap for ternary alloys shows almost nonlinear dependence on the composition. On the other hand, the thermodynamic stability of these alloys was investigated by calculating the excess enthalpy of mixing ΔHm as well as the phase diagram. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-05-03T03:40:47.247638-05:
DOI: 10.1002/pssc.201510247

• Effect of electron blocking layers on the conduction and valence band
profiles of InGaN/GaN LEDs
• Abstract: In this paper we investigate the effect of including an electron blocking layer between the quantum well active region and the p‐type layers of a light emitting diode has on the conduction and valence band profile of a light emitting diode. Two light emitting diode structures with nominally identical quantum well active regions one containing an electron blocking layer and one without were grown for the purposes of this investigation. The conduction and valence band profiles for both structures were then calculated using a commercially available Schrödinger‐Poisson calculator, and a modification to the electric field across the QWs observed. The results of these calculations were then compared to photoluminescence and photoluminescence time decay measurements. The modification in electric field across the quantum wells of the structures resulted in slower radiative recombination in the sample containing an electron blocking layers. The sample containing an electron blocking layer was also found to exhibit a lower internal quantum efficiency, which we attribute to the observed slower radiative recombination lifetime making radiative recombination less competitive. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-05-02T06:10:04.718911-05:
DOI: 10.1002/pssc.201510288

Al2O3 insulator
• Authors: Alexander V. Voitsekhovskii; Sergey N. Nesmelov, Stanislav M. Dzyadukh, Vladimir V. Vasil`ev, Vasiliy S. Varavin, Sergey A. Dvoretsky, Nikolay N. Mikhailov, Maxim V. Yakushev, Georgiy Y. Sidorov
Abstract: The paper presents the results of studies of the admittance of MIS structures based on heteroepitaxial MBE n (p)‐Hg0.78Cd0.22Te with insulator coating SiO2/Si3N4 and Al2O3 in the test signal frequency range 10 kHz‐1 MHz at temperatures ranging from 8 to 220 K. The main parameters of MIS structures with different insulators were determined. MIS structures with Al2O3 have a large enough insulator capacitance (compared to SiO2/Si3N4), a significant modulation capacitance on the CV characteristics, high dielectric strength and low values of the flat‐band voltage. The effective charge density found from the value of the flat‐band voltage and slow interface trap density for structures with Al2O3 comparable with the corresponding densities for structures with SiO2/Si3N4. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-04-14T04:12:17.329356-05:
DOI: 10.1002/pssc.201510227

• Electrical and optical studies of a tellurium‐related defect in
molecular‐beam epitaxy‐grown HgCdTe
• Abstract: Electrical and optical studies of defects in molecular beam epitaxy (MBE)‐grown HgCdTe films, undoped and doped with arsenic, were carried out. By comparing results of ion milling‐assisted Hall‐effect measurements with micro‐Raman spectroscopy data, it was shown that the films contained electrically neutral defects related to excessive tellurium. It is suggested that these defects are Te nanocomplexes and that they are typical of the MBE HgCdTe technology. Under ion milling, they get electrically activated by interstitial mercury and form donor centers with concentration of ∼1017 cm‐3, which allows for detecting them with measurements of electrical parameters of the material. Also, it can be suggested that in films doped with arsenic with high‐temperature cracking, As2 dimers in the arsenic flux react with excessive tellurium and form As2Te3 donor complexes, thus preventing formation of Te nanocomplexes. Arsenic activation annealing may break As2Te3 complexes and release Te, which can again form the complexes under ion milling. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-04-14T04:12:16.310419-05:
DOI: 10.1002/pssc.201510234

• Photosensitive MIS structures with ultrathin dielectric based on
CdXHg1‐XTe (x ∼ 0.4)
• Authors: Valeriy G. Kesler; Alexander A. Guzev, Sergey A. Dvoretskiy, Evgeniy R. Zakirov, Anatoliy P. Kovchavtsev, Zoya V. Panova, Maxim V. Yakushev
Abstract: The work is aimed to studying a possibility of CdHgTe surface passivation and stabilization by tunnel‐thin (∼ 2 nm) native oxide formed by glow discharge plasma oxidation. Kinetics of MCT plasma treatment in two regimes has been obtained. Investigation of the stabilization effect during vacuum annealing and platinum deposition has been performed. It has been established that presence of a native oxide layer on MCT surface results in elimination of mercury out diffusion during the processes. MIS structures with platinum contacts and thin native oxide have been made. They have rectifying behaviour in contrast with structures without the native oxide layer. The barrier height and the detectivity have been determined from the capacitance‐voltage and current‐voltage dependences. The detectivity value of 4×1011cm.Hz1/2W‐1 (at 78 K) determined by dark current shot noise has been reached. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-04-14T04:12:15.186306-05:
DOI: 10.1002/pssc.201510275

• Growth of zinc sulfide by mist chemical vapor deposition depending on mist
size and thermal conditions in susceptor
• Authors: Kazuyuki Uno; Yuichiro Yamasaki, Ping Gu, Ichiro Tanaka
Abstract: Zinc sulfide (ZnS) films were successfully grown by using mist chemical vapor deposition (mist‐CVD) with fine‐channel susceptor made of quartz. For the investigation of growth dynamics, two types of mist generators and two types of susceptors were prepared and distribu¬tion profiles of film thickness were examined. Thermal efficiency of susceptor depends on heat¬penetration efficiency and line‐velocity of the mists, which are influenced by the fine‐channel gap‐height of the susceptors. Using larger size of mists requires higher thermal efficiency in susceptor to obtain a flat thickness distribution. This result indicates that the optimization of the mist size and the susceptor structure is important for the film uniformity of grown films by the mist‐CVD. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-04-14T04:12:13.791215-05:
DOI: 10.1002/pssc.201510309

• Fabrication and characterization of Au/Zn composite electrode on
p‐CdZnTe (111) B plane
• Abstract: Electrode fabrication is a key procedure for preparation of high‐performance CdZnTe detectors, and the metal–semiconductor contact contributes greatly to the performance of detectors. In the present paper, a vacuum evaporation method was used to deposit a Au/Zn composite electrode on the (111) plane of p‐CdZnTe. Based on the AFM, SEM, current–voltage testing and the barrier‐height calculations, the effects of an Au/Zn contact on CdZnTe detector properties were investigated. The results showed that a lower Schottky barrier height was attained by depositing a Au layer on p‐CdZnTe(111) A plane and a Au/Zn double layers on (111) B plane, decreasing the influence of the Te‐enriched surface on the metal–semiconductor contact, and suggesting a better ohmic contact for CdZnTe detectors. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-03-29T03:34:04.771146-05:
DOI: 10.1002/pssc.201510279

• Electronic spectrum of Bi‐related defects in crystalline CdTe
• Authors: Vladimir Krivobok; Sergey Nikolaev, Evgeny Onischenko, Anna Pruchkina, Sergey Kolosov, Yuri Klevkov, Victor Bagaev
Abstract: Using measurements of conductivity and low‐temperature photoluminescence, we have studied electronic levels in the band gap of CdTe:Bi and CdTe:Bi,Cl single crystals grown by the modified Bridgman technique. Three type of deep levels (EV+0.29 eV, EV+0.4 eV, EV+0.72 eV) and Bi‐related shallow acceptor have been observed depending on the doping conditions. Energy spectrum of a shallow Bi‐related acceptor has been measured and its low symmetry has been established. The tentative interpretation for all the levels observed has been proposed. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-03-16T06:20:15.499157-05:
DOI: 10.1002/pssc.201510274

• Growth and characterization of Mg1‐xCdxO thin films
• Abstract: In this paper, we study the growth of thin films of the Mg1–xCdxO alloy in the Mg‐rich range of compositions by using the metal organic chemical vapour deposition (MOCVD) method at low pressure. X‐ray diffraction (XRD) has been used to analyse the compound formation and the progressive incorporation of Cd2+ ions into the cubic MgO lattice. Both, layers with a single‐cubic phase of Mg1–xCdxO and layers with a phase separation, where Cd1–xMgxO and Mg1–xCdxO coexist, have been studied. Finally, a morphological study of the layers has been carried out by using scanning electron microscopy (SEM) and the layers' composition has been measured by energy dispersive X‐ray analysis (EDX). (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-03-16T06:20:14.563297-05:
DOI: 10.1002/pssc.201510276

• Structural, optical and magnetic characteristics of II‐VI
semiconductor nanocrystal‐graphene hybrid nanostructures
• Authors: Andriy I. Savchuk; Ihor D. Stolyarchuk, Serhii A. Savchuk, Eugeniusz M. Sheregij, Jacek Polit
Abstract: CdS, CdTe, ZnO, and ZnO:Co nanocrystals and related hybrid nanostructures, in which the nanoparticles combined with graphene, have been studied. Different chemical approaches for synthesis of II‐VI semiconductor nanocrystal‐graphene hybrids have been applied depending on chemical composition. Transmission electron microscopy characterizations proved the formation of graphene based hybrid nanostructures. Absorption spectra near band‐gap edge have shown changes due to the interaction of the nanocrystals with graphene. The revealed photoluminescence quenching effect in II‐VI semiconductor nanocrystal‐graphene hybrids can be served as evidence for electron transfer from the nanoparticles to graphene. Results of Faraday rotation measurements in doped ZnO:Co nanocrystals and their hybrids at room temperature demonstrated paramagnetic behaviour for both kinds of samples. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-03-16T06:20:13.065783-05:
DOI: 10.1002/pssc.201510283

• Structural properties and vertical transport in ZnSe/CdSe superlattices
grown on an In0.3Ga0.7As metamorphic buffer layer
• Authors: E. A. Evropeytsev; S. V. Sorokin, G. V. Klimko, S. V. Gronin, I. V. Sedova, K. G. Belyaev, S. V. Ivanov, G. Pozina, A. A. Toropov
Abstract: We report on the growth by molecular‐beam epitaxy of short‐period ZnSe/CdSe superlattices (SLs) on an In0.3Ga0.7As metamorphic buffer layer. Such SLs are considered as a promising material for a wide band‐gap photoactive p‐n junction in a hybrid monolithic Ge/InxGa1‐xAs/Iny(Al,Ga)1‐yAs/II‐VI solar cell. Lattice‐matching of the SLs to the In0.3Ga0.7As layer is confirmed by X‐ray diffractometry. Vertical transport of photoexcited carriers is investigated by means of both steady state and time‐resolved photoluminescence techniques in heterostructures containing the ZnSe/CdSe SL with an enlarged quantum well (EQW). Characteristic times of the carrier transport across the SL towards EQW are evaluated in the temperature range 120–300 K. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-03-16T06:20:11.814723-05:
DOI: 10.1002/pssc.201510305

• Influence of source transport rate upon fractions of Mg and Se in
Zn1‐xMgxSeyTe1–y layers grown by metalorganic vapor phase
epitaxy
• Authors: Katsuhiko Saito; Masakatsu Abiru, Eiichiro Mori, Yasuhiro Araki, Daichi Tanaka, Tooru Tanaka, Qixin Guo, Mitsuhiro Nishio
Abstract: The growth of undoped Zn1–xMgx Sey Te1–y layers on (100) ZnTe substrates by metalorganic vapor phase epitaxy has been carried out. The fractions of Mg and Se, Raman property and surface roughness have been characterized as a function of bis‐methylcyclopentadienyl‐magnesium ((MeCp)2Mg) or diethylselenide (DESe) transport rates. It has been demonstrated that the Mg and Se fractions in Zn1–xMgx Sey Te1–y layer can be controlled successfully by these source transport rates. Furthermore, the behaviors of two Raman peaks related to ZnSeTe‐like longitudinal optical phonon mode and MgSeTe‐like one have been clarified for some Mg and Se fractions in Zn1–xMgx Sey Te1–y layers. It has been shown by varying (MeCp)2Mg or DESe transport rates that Zn1‐xMgx Sey Te1–y layer nearly‐lattice‐matched to ZnTe substrate shows low surface roughness. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-03-16T06:20:10.744695-05:
DOI: 10.1002/pssc.201510304

• A comparative study of the gas sensing properties of hierarchical ZnO
nanostructures
• Abstract: Two types of ZnO nanostructure have been fabricated to make a comparative study on their gas sensing performance: the conventional ZnO nanowire arrays were synthesized by hydrothermal method and the hierarchical ZnO nanowires/nanofibers nanostructures were prepared through a combination of the hydrothermal and electrospinning methods. Field emission scanning electron microscopy study showed a quiet homogeneous morphology both for both nanostructures. Three kinds of commonly used gases, such as ethanol, acetone and ammonia were chosen for ZnO nanostructure gas sensing property study. The UV‐Visible spectroscopy measurements showed a higher detection sensitivity of ZnO NWs for ammonia compared to ethanol and acetone, and an enhanced sensing performance for the hierarchical nano‐ structure, which has a higher surface to volume ratio. On the other hand, the enhancement was more obviously in the case of ethanol sensing. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-03-16T06:20:09.844942-05:
DOI: 10.1002/pssc.201510301

• 2D‐localization and delocalization effects in quantum Hall regime in
HgTe wide quantum wells
• Authors: Svetlana V. Gudina; Yurii G. Arapov, Vladimir N. Neverov, Sergey M. Podgornykh, Mikhail R. Popov, Nina G. Shelushinina, Mikhail V. Yakunin, Sergey A. Dvoretsky, Nikolay N. Mikhailov
Abstract: We have measured the longitudinal and Hall resistivities in the quantum Hall regime at magnetic fields B up to 9 T and temperatures T = (2.9–50) K for HgTe/HgCdTe heterostructure with wide HgTe quantum well. The results are analysed within the scaling concept for the conductivity on the delocalized states at the center of the Landau level and within the variable‐range hopping model for the conductivity on the localized states between the Landau levels. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-03-16T06:20:08.88983-05:0
DOI: 10.1002/pssc.201510299

• Tamm plasmon polaritons in the visible spectral region and its optical
properties in ZnSe‐based microcavities
• Abstract: We report on the formation of Tamm plasmon (TP) modes in the visible spectral region at the interface between a Ag film and a ZnSe‐based distributed Bragg reflector (DBR). The tuning of the TP eigenenergies within the stop‐band in dependence on the DBR top layer thickness is investigated by micro‐reflectivity measurements. The experimental findings are compared with calculations using the transfer matrix method. The latter calculations show that strong coupling can be achieved between quantum well (QW) excitons and the TP modes. In addition, the Rabi‐splitting energy can be enhanced in a simple TP structure by increasing the number of QWs inside the top layer of the DBR. When a metal layer is deposited on a cold MC sample, micro‐reflectivity spectra show a blue shift of the cavity resonance. The TP modes are likewise observed in the same MC sample when reducing the top layer thickness of the DBR. This shift of cavity resonance and formation of TP mode are in good agreement with calculations. These results are rather promising in order to realize a spatial confinement of the polaritons by utilizing metal strips. Such channeling of polaritons opens the way to practical demonstration of exciton‐polariton integrated circuits. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-03-16T06:20:08.001662-05:
DOI: 10.1002/pssc.201510296

• Effect of Al doping in the Ag layer of MgZnO/Ag/MgZnO

• Authors: Yukiko Sugimoto; Kanae Igarashi, Shinya Shirasaki, Akihiko Kikuchi
Abstract: Transparent conductive films (TCFs) with dielectric/metal/dielectric (DMD) structure covering the UVA (λ = 315–380 nm) and visible wavelength region (380–780 nm) were fabricated using Al‐doped Mg0.4Zn0.6O (AMZO) dielectric and 1.7 at% Al‐doped Ag (Ag(Al)) metal layers. The AMZO/Ag(Al)/AMZO‐DMD film with a 7 nm thick Ag(Al) layer after annealing in vacuum at 400 °C showed superior performance as a TCF, i.e., average transmittance from UVA to visible region (315–780 nm) of 88.2% and sheet resistance of 7.6 Ω/sq. The effect of Al doping on optical transmission, sheet resistance, surface morphology, and thermal durability of the AMZO/Ag(Al)/AMZO‐DMD films were also investigated. The 1.7 at% Al doping suppressed the initial island growth of the thin Ag layer and the plasmon resonance absorption dipped in the optical transmission spectra. Al doping in the Ag layer also improved the thermal durability of AMZO/Ag/AMZO‐DMD films. The threshold temperature for Ag void formation caused by metal segregation increased from 300 °C (DMD with a pure Ag layer) to 400 °C (DMD with an Al‐doped Ag layer). (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-03-16T06:20:07.072077-05:
DOI: 10.1002/pssc.201510290

• Influence of the number of electronically coupled CdSe/ZnSe QD planes on
characteristics of optically pumped green lasers
• Authors: I. V. Sedova; E. V. Lutsenko, S. V. Sorokin, A. G. Vainilovich, S. V. Gronin, G. P. Yablonskii, M. Aljoheni, A. Aljerwi, A. Alyamani, S. V. Ivanov
Abstract: Structural properties and laser characteristics of true green (λ=530‐550 nm) ZnSe‐based optically pumped laser heterostructures with several (up to three) CdSe/ZnSe quantum dot (QD) planes in the active region were studied in details. Optimization of the MBE growth conditions to reduce the non‐equilibrium defect density in the active region as well as the active region design allowed obtaining nearly the same rather low laser threshold values of Ithr∼4 kW/cm2 at Lcav∼100 μm for all the samples. The internal laser parameters were determined by measuring the laser threshold and differential quantum efficiency as functions of the cavity length. The design of laser structures provides high excitation homogeneity of the active region due to strong enough carrier tunneling between QD layers spaced by 5‐nm‐thick ZnSe barriers, which is confirmed by the sub‐linear dependence of the transparency excitation intensity versus number of QD planes in the active region (IT = 0.556, 1.037, and 1.311 kW/cm2). The triple‐QD‐plane laser structure demonstrates significant increase in characteristic gain up to ΓG0=161.62 cm‐1. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-03-16T06:20:05.605287-05:
DOI: 10.1002/pssc.201510289

• Numerical modeling and simulation of ZnO nanowire devices for energy
harvesting
• Abstract: Duo to their multifunctional properties, the piezoelectric ZnO nanowires are of great interest in many applications such as the energy harvesting. In this work, a numerical modelling based on the finite element method was performed to study the potential distribution inside the ZnO nanowire and the impact of the geometric parameters on the generated piezopotential both in bending and compression deformation. In this context, a nanowire discharge behavioural study was carried out in order to obtain an analytic expression which connects the piezopotential and nanowire geometrical parameters in the bending deformation. Furthermore, a heuristic algorithm Particle Swarm Optimization (PSO) has been used in order to improve the electromechanical performance of ZnO nanowire based nanogenerator. It is fount that under the same order of force applied on a nanowire, the compression mode results in a piezopotential 9 times larger than that in the bending deformation. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-03-16T06:10:17.801655-05:
DOI: 10.1002/pssc.201510270

• Electron–phonon interaction in II‐VI quantum wells
• Authors: A. Yu. Maslov; O. V. Proshina
Abstract: The theory of charge‐particle interaction with polar optical phonons is developed for II‐VI compounds‐based heterostructures in which the symmetries of the quantum well and barrier materials are different. The parameters of the electron–phonon interaction are found for the structures in which the material of hexagonal symmetry is used for creating a quantum well or barriers. It is shown that the electron–phonon interaction depends on the anisotropy of the dielectric parameters of the hexagonal material for both cases. Compared to previously obtained results for a quantum well based on the material of cubic symmetry both enhancing and weakening of polaron effects are possible. The obtained results are applied to the explanation of polaron mass magnitude in the quantum well based on ZnO‐ZnMgO. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-03-16T06:10:16.973941-05:
DOI: 10.1002/pssc.201510263

• Investigation of yellow/green II‐VI compound semiconductor laser
diode structures on InP substrates
• Authors: Ryohei Kobayashi; Shingo Takamatsu, Koji Fukushima, Katsumi Kishino, Ichirou Nomura
Abstract: II‐VI‐compound‐semiconductor laser diode (LD) structures on InP substrates were investigated using device simulations and waveguide analysis. Our simulations showed that electron injection from the n‐cladding into the active layer is hindered by the n‐side barrier layer between the n‐cladding and active layer. Consequently, holes are not injected into the active layer but instead leak to the n‐side layers. It was shown that carrier injection efficiency can be improved by removing the n‐barrier. On the contrary, no large differences were observed between the optical confinement factors of the LD structures with and without the n‐barrier layer. In experiments, we have fabricated the LD structures with and without the n‐barrier layer on InP substrates using molecular beam epitaxy. The turn‐on voltage of the device without the n‐barrier was smaller than that for the device with the n‐barrier by about 5 V. Spontaneous orange emissions around 603 nm were observed for the devices without the n‐barrier. In contrast, no emission was observed for the devices with the n‐barrier. These results prove that the carrier injection into the active layer is enhanced by the removal of the n‐barrier, leading to improved the device performances. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-03-16T06:10:16.108611-05:
DOI: 10.1002/pssc.201510255

• Effects of strontium concentration on structural, electronic, optical and
thermodynamic properties of Pb1‐xSrxS
• Authors: Jazia Zeroual; Salima Labidi, Malika Labidi, Rachid Bensalem
Abstract: Theoretical investigations of structural, electronic, optical and thermodynamic properties of Pb1‐xSrxS with rocksalt crystal structure are reported, theoretical calculations are mainly based on the full potential linearized augmented plane wave (FP‐LAPW) method within the density functional theory (DFT) the generalized gradient approximation (GGA) of Perdew et al. The dependence of the lattice parameters, band gaps, dielectric constants, refractive indices, and mixing entropies on the composition x were analyzed mainly for x = 0, 0.25, 0.50, 0.75 and 1. The lattice constant for Pb1‐xSrxS exhibits a marginal deviation from the Vegard’s law. A significant deviation of the bulk modulus from linear concentration dependence was observed for the alloy. The microscopic origins of the gap bowing were detailed and explained. The composition dependence of the dielectric constant and refractive index was studied using different models. Besides, a regular‐solution model is used to investigate the thermodynamic stability of the alloys, which mainly indicates a phase miscibility gap. In fact and since there is a good agreement between our main results and the available experimental data for the binary compounds which may be a support for the results of the ternary alloys reported here for the first time. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-03-16T06:10:14.867908-05:
DOI: 10.1002/pssc.201510237

• Comparative studies of CdSe/ZnSe quantum dot structures epitaxially grown
with or without a sub‐monolayer CdTe stressor
• Authors: M. V. Rakhlin; K. G. Belyaev, I. V. Sedova, S. V. Sorokin, S. V. Gronin, A. A. Usikova, A. A. Sitnikova, P. N. Brunkov, S. V. Ivanov, A. A. Toropov
Abstract: We report on comparative studies of the emission properties of CdSe/ZnSe quantum dots (QDs) grown by molecular beam epitaxy either with or without predeposition of a sub‐monolayer CdTe stressor, and in the latter case, either with or without in‐situ thermal annealing. The emission of a limited number of QDs was registered in all samples by micro‐photoluminescence confocal spectroscopy through 500‐nm‐size round apertures opened in a non‐transparent gold mask by ball assisted etching technique. The measurements reveal the lowest density of emitting QDs in the sample grown with the in‐situ annealing that is attributed to both ripening of the CdSe QDs and strain relaxation in the largest QDs, followed by formation of defects serving as centres of nonradiative recombination. The employment of the CdTe stressor causes narrowing of the total QDs emission band and simultaneous broadening of the single‐QD lines that is consistent with the formation of a relatively homogeneous dense array of type‐I CdSe/ZnSe QDs adjoining type‐II Zn(Cd)Te/ZnSe nanostructures. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-03-03T09:15:19.330217-05:
DOI: 10.1002/pssc.201510302

• Growth, structural and optical properties of ZnO/ZnMgO core‐shell
heterostructures
• Authors: S. A. Said Hassani; C. Sartel, C. Vilar, G. Amiri, A. Lusson, V. Sallet, P. Galtier
Abstract: ZnO nanowires have been grown by metalorganic chemical vapor deposition on sapphire substrates. The use of N2O and DEZn as oxygen and zinc precursors combined with high temperature leads to the spontaneous growth of vertical ZnO nanowires (NWs) on underlying three dimensional islands present at the bottom of each nanowire. These nanowires are grown along the c axis of the wurtzite structure, exhibit well defined m‐plane facets and are free of extended defects. This configuration is favorable to band‐gap engineering studies. Based on this, we have grown a series of radial ZnO/ZnMgO shells and quantum wells with different thicknesses and Mg concentrations. ZnxMg1‐xO alloys have been grown using O2, (MCp)2Mg and DEZn as oxygen, magnesium and zinc precursors. Low temperature photoluminescence spectroscopy and transmission electron microscopy have assessed Mg concentrations in the shell up to 20 %. Electron diffraction reveals that the ZnMgO alloyed structure is, at least partially, ordered. Micro‐photoluminescence performed on a single ZnO/ZnMgO coreshell nanowire including a quantum well exhibits luminescence properties, with a lateral quantum confined emission. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-03-03T09:15:16.824029-05:
DOI: 10.1002/pssc.201600001

• Electric field inhomogeneity in ohmic‐type CdTe detectors measured
by time‐of‐flight technique
• Authors: Kazuhiko Suzuki; Takayuki Sawada, Satoru Seto
Abstract: The bias‐induced instability of the internal electric field in Ohmic‐type CdTe gamma‐ray detectors is investigated by using the time‐of‐flight technique. Based on the solution of one dimensional Poisson equation, transient current waveforms at different delays of laser excitation from the bias application and at different temperatures are analysed It is shown that under DC bias application, the internal electric field decreases with depth because of the positive space charge buildup in the detectors. Further, the origin of the space charge is attributed to the injection and successive trapping of holes from the anode side at the early stage of evolution and then later to the thermal release of electrons from a deep donor at 0.64 eV. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-03-03T09:15:14.993931-05:
DOI: 10.1002/pssc.201510239

• Manifestation of strong d‐p hybridization in photoluminescence
spectra of ZnO:Ni and ZnO:Co
• Authors: V. I. Sokolov; N. B. Gruzdev, V. A. Pustovarov, V. N. Churmanov
Abstract: For the first time photoluminescence and photoluminescence excitation spectra for ZnO:Co and ZnO:Ni crystals were obtained at the excitation by the synchrotron radiation in the interval of energy of (3.7‐21) eV, T = 8 K. It is shown that these spectra are formed by intense radiative transitions through 3d charge transfer states in the band gap. This fact evidences about much stronger hybridization between d‐states of impurity and p‐states of anions in comparison with other II‐VI:3d compounds. It is very important for applications in optoelectronics, for visualization of ultraviolet radiation and understanding of photocatalytic activity of ZnO:3d nanocrystals in the visible region of the spectrum. From the comparison of PLE spectra for ZnO:Co and ZnO:Ni with the spectrum of calculated DOS for ZnO it is revealed a visible transformation of part of valence band states due to a strong d‐p hybridization. Obtained results allow us to consider ZnO:3d as a compounds with a strong correlations. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-03-03T09:15:08.729506-05:
DOI: 10.1002/pssc.201510241

• Dislocations in MCT heteroepitaxial structures on (013) substrates and
possibilities of dislocation density reducing
• Authors: Yury Sidorov; Ivan Loshkarev, Irina Sabinina, Evgeny Trukhanov, Vasily Varavin, Maksim Yakushev, Aleksei Kolesnikov
Abstract: Dislocations in heterostructures CdTe/ZnTe/GaAs(013) and CdTe/ZnTe/Si(013) were investigated using selective etching and transmission electron microscopy. The calculations of critical film thickness hc were fulfilled for 12 various slip systems, the experimental results were obtained for 4 of them. Misfit dislocations are introduced in a ZnTe film at the stage of formation of the first monolayers. With their introduction, the crystal lattices of the substrate and the film unfold relative each other that is confirmed by X‐ray diffraction measurements. An increase in the dislocation density into the CdTe and HgCdTe films was observed using layer‐by‐layer etching. That is testifies to the annihilation of threading dislocations during the growth of CdTe and MCT films. The dislocation annihilation rate is higher in films grown on GaAs(013) than on Si(013). Perhaps this is due to the higher proportion of gliding dislocations in CdTe films on GaAs substrates (013). It was made annealing of MCT films under cyclic temperature change in such way that activity of MCT components was changed to enhance the non‐conservative motion of dislocations. As a result, the density of penetrating dislocations in the active areas in MCT films on silicon substrates was decreased to the value of 2.5×106 cm‐2. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-03-03T09:15:05.639755-05:
DOI: 10.1002/pssc.201510243

• Development of ZnSe‐based organic–inorganic hybrid
UV‐APDs array
• Authors: Tomoki Abe; Ryoichi Inoue, Takeru Fujimoto, Kenta Tanaka, Shigeto Uchida, Hirofumi Kasada, Koshi Ando, Kunio Ichino
Abstract: Recently, we have developed organic (PEDOT:PSS)–inorganic (ZnSSe) hybrid avalanche photodiode (APD) with long life time and its array. In this article, we review the development of the organic–inorganic hybrid‐type ZnSe‐based UV‐APDs array. We used PEDOT:PSS as UV transparent hole‐transport conducting polymer window layers formed by inkjet printing technique. We have successfully fabricated low dark current ultraviolet hybrid APDs. The hybrid APD device has exhibited very low voltage APD operation at 29 V and extremely low dark current of 10‐11 A/mm2 in the avalanche breakdownregion. The hybrid APD also has shown maximum multiplication factor of 45 and high sensitivity ∼ 3 A/W at the ultraviolet region (∼ 300 nm). A stable device operation is established using polyimide passivation and sealed package with N2 atmosphere. We also demonstrated integrated devices operation in APD mode with very small photosignal cross‐talk of ‐50 dB. The tail of current‐profile was determined as 8 μm by using in‐plane electron‐beam induced current (EBIC) measurement. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-03-03T09:15:02.679457-05:
DOI: 10.1002/pssc.201510273

• The local electron interaction with crystal defects in wurtzite CdS
• Authors: Orest Malyk; Volodymyr Rodych, Hryhoriy Il'Chuk
Abstract: In the present paper the interaction of electrons with different types of defects with the potential of the limited action radius – polar and nonpolar optical phonons, piezoelectric and acoustic phonons, static strain centers, ionized and neutral impurities – in cadmium sulfide is considered. The dopant concentration in observed CdS crystals was in the limits of 5.5×1015 ÷ 1.1×1019 cm‐3. The dependences of the electron mobility and Hall factor on temperature in the interval 10 ÷ 400 K are investigated. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-03-03T09:14:59.069149-05:
DOI: 10.1002/pssc.201510281

• Peculiarities of CdS nanocrystal formation at annealing of a
Langmuir‐ Blodgett matrix
• Authors: Kirill Svit; Dmitry Protasov, Sergey Teys, Larisa Sveshnikova, Yakushev Maksim, Konstantin Zhuravlev
Abstract: Formation and assembling of CdS nanocrystals (NC) on highly‐ordered pyrolytic graphite (HOPG) and on oxidized silicon substrates have been investigated by atomic force microscopy (AFM) and scanning tunneling microscopy (STM). NC were initially formed within a Langmuir‐Blodgett (LB) matrix of cadmium behenate. The LB matrix was then removed by annealing in an ammonia atmosphere. It is shown that the NC self‐assembling is mainly determined by the LB matrix wetting properties. In case of wettable HOPG substrate homogeneous matrix evaporation occurs that leads to coarsening of the NC arrays as the main self‐assembly process. Otherwise, NC prepared on non‐wettable SiO2‐Si substrate demonstrate arrays formation determined by the LB matrix dewetting process. For the both cases, the influence of kinetic limitations connected with matrix evaporation rate on the self‐assembly process is observed. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-03-03T09:14:57.51281-05:0
DOI: 10.1002/pssc.201510285

• Observation of topological phase transition by terahertz photoconductivity
in HgTe‐based transistors
• Authors: A. M. Kadykov; C. Consejo, M. Marcinkiewicz, L. Viti, M. S. Vitiello, S. S. Krishtopenko, S. Ruffenach, S. V. Morozov, W. Desrat, N. Dyakonova, W. Knap, V. I. Gavrilenko, N. N. Mikhailov, S. A. Dvoretsky, F. Teppe
Abstract: We have found the possibility to probe the magnetic field‐driven topological phase transition in HgTe‐based transistors by measuring their Terahertz photoconductivity response. At the critical magnetic field to which zero‐mode Landau levels cross, we have observed a pronounced photoconductivity peak independent on incident frequency and carrier concentration. Our results pave the way towards terahertz topological field effect transistors. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-02-25T03:13:04.847987-05:
DOI: 10.1002/pssc.201510264

• Low pressure MOVPE growth and characterization of ZnTe homoepitaxial
layers
• Authors: Mitsuhiro Nishio; Katsuhiko Saito, Masakatsu Abiru, Eiichiro Mori, Yasuhiro Araki, Daichi Tanaka, Tooru Tanaka, Qixin Guo
Abstract: The growth rate and photoluminescence (PL) spectrum of ZnTe homoepitaxial layer grown at a reactor pressure of 500 Torr by metalorganic vapor phase epitaxy have been clarified as a function of substrate temperature. An optimum substrate temperature for obtaining ZnTe layers with better PL property is determined by taking into account the growth rate behavior. Furthermore, the growth rate, PL spectrum, surface roughness and surface morphology of ZnTe layer have also been investigated by varying reactor pressure. With increasing reactor pressure, both the PL property and surface roughness of ZnTe layer are improved and subsequently become degraded, according as the growth rate increases monotonically and then shows saturated tendency. Change in the surface morphology of ZnTe layer with the increase of reactor pressure resembles that with the decrease of substrate temperature, probably due to the change from mass‐transport regime to surface kinetics one. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-02-25T03:13:00.722975-05:
DOI: 10.1002/pssc.201510240

• Luminescence dynamics of hybrid ZnO nanowire/CdSe quantum dot structures
• Abstract: Colloidal CdSe quantum dots (QDs) functionalized with different organic linker molecules are attached to ZnO nanowires (NWs) to investigate the electron transfer dynamics between dots and wires. After linking the quantum dots to the nanowires, the photo‐induced electron transfer (PET) from the QDs into the NWs becomes visible in the PL transients by a decrease of dot luminescence decay time. The different recombination paths inside the QDs and the PET process are discussed in the framework of a rate equation model. Photoconductivity studies confirm the electron transfer by demonstrating a strong enhancement of the wire photocurrent under light irradiation into the dot transition. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-02-25T03:12:59.796045-05:
DOI: 10.1002/pssc.201510253

• Photoconductive properties of undoped and nitrogen‐doped ZnO single
crystals in various ambiences
• Authors: Takami Abe; Shuzo Takahashi, Shuhei Kamada, Akira Nakagawa, Tetsuya Chiba, Michiko Nakagawa, Shigeki Chiba, Yasuhiro Kashiwaba, Masahiro Daibo, Ikuo Niikura, Yasube Kashiwaba, Hiroshi Osada
Abstract: The effects of ambiences on photoconductive properties of the Zn‐face of undoped ZnO and nitrogen‐doped ZnO (ZnO:N) single crystals are described. Oxygen (O2) gas affected the photocurrent spectra of the Zn‐face of both single crystals. The photocurrent was smallest in O2 gas and was largest in the vacuum ambience. The influence of ambience was very small in the visible light region but was large in the UV region. Regardless of the ambience, photocurrent of the Zn‐face of ZnO:N showed no sensitivity in the visible region. The decay time response of undoped ZnO and ZnO:N single crystals was also affected by the ambience. Decay time responses of both single crystals were fastest in O2 gas and were slowest in the vacuum ambience. The decay time response of the ZnO:N single crystal was faster than that of the undoped ZnO single crystal. These results showed that the effect of oxygen‐mediated surface recombination is strong in both large single crystals with very small surface‐to‐volume ratio and no grain boundary effect. The results also showed that doped nitrogen decreases the density of electron and hole traps near the surface region of the crystals. It is thought that steepness of band bending near the surface of a ZnO:N single crystal is smaller than that of an undoped ZnO single crystal. In conclusion, the Zn‐face of a ZnO:N single crystal sealed with O2 gas is useful as a photoconductive type UV sensor. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-02-25T03:12:58.907655-05:
DOI: 10.1002/pssc.201510260

• Unintentional nitrogen incorporation in ZnO nanowires detected by electron
paramagnetic resonance spectroscopy
• Authors: J. E. Stehr; W. M. Chen, N. K. Reddy, C. W. Tu, I. A. Buyanova
Abstract: Unintentional incorporation of nitrogen in ZnO nanowires (NWs) grown by rapid thermal chemical vapor deposition is unambiguously proven by electron paramagnetic resonance spectroscopy. The nitrogen dopants are suggested to be provided from contaminations in the source gases. The majority of incorporated nitrogen atoms are concluded to reside at oxygen sites, i.e. in the atomic configuration of nitrogen substituting for oxygen (NO). The NO centers are suggested to be located in proximity to the NW surface, based on their reduced optical ionization energy as compared with that in a bulk material. This implies that the defect formation energy at the NW surface could be lower than its bulk value, consistent with previous theoretical predictions. The obtained results underline that nitrogen can be easily incorporated in ZnO nanostructures which may be of advantage for realizing p‐type conducting ZnO via N doping. On the other hand, the awareness of this process can help to prevent such unintentional doping in structures with desired n‐type conductivity. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-02-25T03:12:58.007038-05:
DOI: 10.1002/pssc.201510261

• Characterization of carrier concentration in ZnO nanowires by scanning
capacitance microscopy
• Abstract: Scanning capacitance microscopy (SCM) has been investigated on Ga doped ZnO staircase multi‐layers grown by molecular beam epitaxy (MBE) and ZnO NWs grown by chemical bath deposition (CBD). It is found that SCM data amplitude experiences a monotonic decrease with increasing Ga concentration from 2×1017 cm‐3 to 3×1020 cm‐3, indicating SCM being an appropriate technique for two dimensional dopant/carrier profiling in ZnO at nanoscale. For ZnO nanowires (NWs), a planariz‐ation process was developed based on dip‐coating of silica sol‐gel and chemical‐mechanical polishing. Then ZnO NWs were well detected from the silica matrix by SCM and the residual carrier concentration inside them was estimated through calibration method to be between 5×1017 cm‐3 and 2×1018 cm‐3. Finally, the result was compared with that obtained from conventional capacitance‐voltage (C‐V) measrement and their difference was discussed. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-02-17T04:10:06.765556-05:
DOI: 10.1002/pssc.201510268

• Role of electron‐phonon interaction in the temperature dependence of
the phonon mode frequency in II‐VI compound alloys
• Abstract: We present an experimental investigation of the temperature dependence of the TO‐phonon mode frequencies for the HgTe‐based II‐VI semiconductor solid solutions. In the case of the ternary Hg0.9Zn0.1Te solid solution was shown a discontinuity in the temperature dependence of the HgTe‐like TO‐mode and of the ZnTe‐like TO‐mode, similar to the Hg0.885Cd0.115Te system [Sheregii et al., Phys. Rev. Lett. 102, 045504 (2009)]. A generalization of the theoretical temperature shift of the phonon mode frequency as analytic equation is derived that includes both the anharmonic contribution and the electron‐phonon e‐p interaction which in this case is returnable the electron subsystem effect on the phonon one. Data show that our equation satisfactorily describes the temperature shift of both Hg0.885Cd0.115Te and Hg0.9Zn0.1Te containing Dirac point (Eg = Γ6–ΓΓ8 = 0) although one of the two constants describing the anharmonic shift of the HgTe‐like mode should be positive what is abnormal too. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-02-17T04:10:05.464365-05:
DOI: 10.1002/pssc.201510236

• Improvement of thermal stability of p‐type ZnO:(Al,N) fabricated by
oxidizing Zn3N2:Al thin films
• Authors: Y. F. Wang; D. Y. Song, L. Li, B. S. Li, A. Shen, Y. Sui
Abstract: The authors report the fabrication of p‐type ZnO thin films with improved thermal stability. The p‐type ZnO thin films were obtained by oxidizing Zn3N2:Al thin films in an oxygen ambient. Both Zn3N2:Al and Zn3N2 thin films were deposited on fused silica substrates at 100 °C by megnetron sputtering. X‐ray diffraction (XRD) measurements showed that the ZnO thin films obtained from by oxiding Zn3N2:Al, have preferred (002) orientation. On the other hand, ZnO films obtained by oxidizing Zn3N2 are polycrystalline. The optical band gap of ZnO (3.294 eV) obtained by annealing Zn3N2:Al thin films is narrower than that of the ZnO (3.31 eV) obtained by annealing Zn3N2. P‐type ZnO films were formed by annealing Zn3N2:Al at temperatures above 600 °C. A maximum hole density of 1.4 x 1016 cm‐3 was obtained in a film annealed at 800 °C. In contrast, only n‐type ZnO can be produced from oxidizing Zn3N2. Our results indicate that the Al can stabilize the nitrogen acceptors in ZnO thin films. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-02-09T02:40:20.636144-05:
DOI: 10.1002/pssc.201510164

• RT ZnSe‐based lasers and laser arrays pumped by low‐energy
electron beam
• Authors: M. M. Zverev; S. V. Sorokin, N. A. Gamov, E. V. Zhdanova, V. B. Studionov, I. V. Sedova, S. V. Gronin, S. V. Ivanov
Abstract: The properties of an electron‐beam‐pumped ZnSe‐based laser array consisting of 6 one‐dimensional arrays, each comprising 10 single laser elements, have been studied. The peak output power up to 80‐100 W at room temperature in “true” green (λ = 547 nm) spectral range has been demonstrated by using for pumping electrons with the accelerating energy as low as 5.6 keV. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-02-09T02:40:19.821422-05:
DOI: 10.1002/pssc.201510251

• Evidence of exchange interaction of localized carriers and transition
metals in diluted II‐VI nanostructures: ODMR study
• Authors: P. G. Baranov; N. G. Romanov, D. O. Tolmachev, A. S. Gurin, B. R. Namozov, Yu. G. Kusrayev, G. Karczewski, S. Orlinskii, C. De Mello Donega, J. Schmidt
Abstract: Optically detected magnetic resonance study of (CdMn)Te/(CdMg)Te quantum wells allowed to reveal the formation of exchange‐coupled complexes consisting of Mn ions and localized holes in quantum wells with excess hole concentration and the directional electron tunneling towards wider wells in multiple quantum well structures. The existence of a distribution of Mn‐hole complexes that differ in a number of Mn ions interacting with a localized hole is justified. In colloidal cobalt doped ZnO nanocrystals, several nm in diameter, the interaction between the magnetic ions and the shallow donor electron in the confined system of ZnO quantum dots has been revealed. Direct evidence of interaction of Co ions with the interstitial Li shallow donor in the ZnO nanocrystal core and hyperfine coupling with 1H in the quantum dot shell have been demonstrated. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-02-09T02:40:18.924974-05:
DOI: 10.1002/pssc.201510249

• p‐d charge transfer excitons in Zn1‐xNixO under inner shell
excitation
• Authors: V. N. Churmanov; V. I. Sokolov, N. B. Gruzdev, V. Yu. Ivanov, V. A. Pustovarov
Abstract: The paper presents results of the study of two narrow luminescence lines I1 and I2 at the energies of 3.339 and 3.393 eV respectively in solid state solutions Zn1‐xNixO. The luminescence spectroscopy with a sub‐nanosecond time resolution upon selective photoexcitation in the energy range of the inner shell Zn M‐edge absorption was used to promote the earlier proposed mechanism of the I1 and I2 lines origin. Photoluminescence spectra of solid state solutions Zn1‐xNixO at fast and slow time windows under soft X‐ray excitation are discussed. The doublet of I1 and I2 lines is believed to arise due to the radiative annihilation of p‐d excitons. Different possible mechanisms of emergence of two narrow luminescence lines I1 and I2 in solid state solutions Zn1‐xNixO are considered. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-02-09T02:40:18.016128-05:
DOI: 10.1002/pssc.201510245

• Neutronographic characterization of II‐VI cubic crystals highly
doped by 3d ions: on possible tendencies to structure rearrangements in
the sphalerite crystal lattice
• Abstract: Fine features of the crystal structure of Zn0.9Ni0.1S, Zn0.9V0.1Se, Zn0.95Fe0.05Se semiconductor cubic single crystals have been characterized by neutron scattering at room temperature. It has been revealed that neutron‐diffraction scans of the single crystals, in addition to intense Bragg reflections of face‐centered cubic phase, contain a complex system of diffuse scattering maxima, included superstructure reflections. The superstructure diffuse maxima are found placed on reciprocal lattice knots corresponding with the wave vectors q = (1/3 1/3 1/3) 2π/ac (ac is the cubic lattice parameter), which is interpreted as a manifestation of pretransition state. It is proposed that the revealed destabilized structure state means pretransition of reconstructive structure transformation from the cubic phase to the hexagonal phase. Strong perturbations caused by 3d ions doping lead to a collective response of the cubic lattice of the II‐VI matrices, displacing atomic planes in shears, and tend to induce the transformation. Such a complicated structure state determines nonuniform deformation field supporting possibilities to form long‐wave superstructures. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-02-09T02:40:17.228333-05:
DOI: 10.1002/pssc.201510231

• Contents: Phys. Status Solidi C 7–9/2016
• Pages: 399 - 405
PubDate: 2016-07-26T05:23:36.982605-05:
DOI: 10.1002/pssc.201670130

• II‐IV Compounds and Related Materials
• Authors: Christophe Testelin; Pierre Galtier, Vincent Sallet
Pages: 406 - 407
Abstract: The 17th International Conference on II–VI Compounds and Related Materials was held at the Campus des Cordeliers, in the historical center of Paris, France, from September 13th to 18th. II–VI 2015 has followed the path of a suc‐cessful series of biennial conferences which started in Durham (UK) in 1983. Recent conferences were or‐ganized in Niagara Falls (USA, 2003), Warsaw (Po‐land, 2005), Jeju (Korea, 2007), Saint Petersburg (Russia, 2009), Mayan (Mexico, 2011), and Na‐gahama (Japan, 2013). The II–VI conference aims at providing an international forum for scientists, students and indus‐try representatives, facilitating the exchange of new ideas and establishing fructuous scientific contacts. The ambition is to report the newest developments in basic and applied research on II–VI and re‐lated compounds such as oxides and chalcopyrite semiconductors. The topics cover also novel synthe‐sis techniques, new physical properties and innova‐tive device development. Let us note that for this last edition, the scope has been extended to Related Mate‐rials like photovoltaic materials and novel 2D sys‐tems (dichalcogenides and topological insulators). Gathering 240 participants, II–VI Paris 2015 has fulfilled its mission, with a scientific pro‐gram presenting three plenary review lectures, 15 in‐vited talks, 64 contributed talks and about 200 con‐tributed poster presentations. A special session has been devoted to the memory of Prof. Fritz Henneber‐ger from Humboldt University, Berlin. Following the conference, this issue of physica status solidi offers a variety of basic and applied studies on optical, electrical and mag‐netic properties of II–VI compounds, related materials and devices. Achievements in practical ap‐plications of II–VI compounds will be found in infrared, visible and UV range detectors, optoelec‐tronic devices, photovoltaics. The proceedings edition also emphasizes new trends and pioneering directions, towards original related materials and devices. A total of 78 articles are published in pss  (b) (11), pss RRL (1) and pss  (c) (66). We wish that all participants would appreciate to redis‐cover and thoroughly read some of the nice results presented in Paris. We thank all contributors and reviewers who made the edition of II–VI Paris Proceedings a great success and hope the conference as well as the unique atmosphere of Paris will remain in your heart and memory!
PubDate: 2016-07-26T05:23:32.386499-05:
DOI: 10.1002/pssc.201670131

• Traveling heater method growth and characterization of CdMnTe crystals for
• Authors: Wenqi Wu; Jijun Zhang, Linjun Wang, Jiahua Min, Xiaoyan Liang, Xuliang Wen
Pages: 408 - 412
Abstract: In this paper, the Cd0.9Mn0.1Te (CdMnTe) crystals were grown by the self‐designed Traveling Heater Method (THM) crystal growth system. Two types of polycrystalline CdMnTe feed ingots synthesized in a traditional rocking furnace and in a vertical Bridgman furnace were adopted during the THM growth, and the as‐grown crystals were denominated as CMT1 and CMT2, respectively. The crystal and detector properties, including the Te inclusions, Mn composition, PL spectrum, electrical and energy response properties were characterized. The results showed that the CMT2 ingot had less Te inclusion and more uniform Mn composition distribution along the ingot than CMT1 ingot. During the THM growth, the polycrystalline feed material synthesized by VB technique favoured a smooth and low concave growth interface, which decreased the formation of Te inclusions and Mn variation in the ingot. The resistivity of the CdMnTe crystal grown by THM was in the range of (0.5‐4)×1010 Ω·cm. The PL spectra indicated that CMT2 crystal possesses higher crystalline quality as compared to CMT1 crystal, with lower impurity concentration and defects. The fabrication CdMnTe single element planar detectors under the 59.5 keV 241Am radiation showed that the energy resolution of CMT1 and CMT2 crystals was 17.2% and 12.7%, respectively. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-02-03T06:40:20.053808-05:
DOI: 10.1002/pssc.201510226

• Crystallographic and optical characterizations of Ag(Ga,Al)Te2 layers
grown on c ‐plane sapphire substrates by closed space sublimation
• Authors: Aya Uruno; Yuji Takeda, Tomohiro Inoue, Masakazu Kobayashi
Pages: 413 - 416
Abstract: Ag(Ga,Al)Te2 layers were grown by the closed space sublimation method on c ‐plane sapphire substrates. The source used was AgAlTe2/AgGaTe2 mixture or AgAlTe2/Ga2Te3 mixture. The crystallographic property of Ag(Ga,Al)Te2 layers was analyzed by X‐ray diffraction (XRD). XRD spectra of layers exhibited very strong 112 diffraction peaks regardless of the variation of the source material mixture. In addition to crystallographic characterizations, optical properties of the Ag(Ga,Al)Te2 layer were evaluated through transmittance measurements. The bandgap energy was decreased when the source mole ratio of Al to Ga was decreased. It was revealed that control regulation of x composition of Ag(Ga1‐x,Alx)Te2 was feasible by varying the source mole ratio Al/(Ga+Al). (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-02-03T07:10:08.461123-05:
DOI: 10.1002/pssc.201510269

• MOCVD growth of ZnO nanowires on Ni–W metallic substrates
• Pages: 430 - 434
Abstract: Here we investigate the possibility to grow ZnO nanowires on (100) textured Ni‐W substrates by MOCVD at 850 °C. Due to the oxidation of Ni, direct growth of ZnO nanowires on those metallic substrates was not achieved whereas it was easily obtained on sapphire in the same conditions. Therefore, a study of a ZnO buffer layer grown at low temperature was performed in order to prevent the NiO formation. The morphology and the crystallographic orientation of the as‐grown interfacial layers were characterized by scanning emission microscopy (SEM) and XRD diffraction, and are shown to depend on the growth temperature. Subsequently, the growth of ZnO nanowires was carried out on ZnO buffer/Ni‐W pseudo‐substrates. The SEM observations reveal the growth is not homogeneous and depends on the grain orientation. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-02-03T07:10:15.299919-05:
DOI: 10.1002/pssc.201510308

• ZnTe layers on R ‐ and S ‐plane sapphire substrates
• Pages: 435 - 438
Abstract: ZnTe epilayers were grown on R ‐plane ($10 \bar 1 4$) and S ‐plane ($10 \bar 1 1$) sapphire substrates by molecular beam epitaxy, and the crystal orientation and the optical property were studied. The crystal orientation of ZnTe layers on sapphire substrates was studied using X‐ray diffraction pole figure measurements. It was confirmed that (111)‐oriented domains were formed on the R ‐plane as well as on the S ‐plane substrate. Layers grown on R ‐plane exhibited higher film quality. From the low‐temperature photoluminescence, emissions caused by ZnTe exciton were observed. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-02-09T02:40:11.005934-05:
DOI: 10.1002/pssc.201510265

• Acceptor states in HgCdTe films grown by molecular‐beam epitaxy on
GaAs and Si substrates
• Authors: M. V. Yakushev; K. D. Mynbaev, N. L. Bazhenov, V. S. Varavin, N. N. Mikhailov, D. V. Marin, S. A. Dvoretsky, Yu. G. Sidorov
Pages: 469 - 472
Abstract: A study of defects in HgCdTe films grown by molecular‐beam epitaxy on GaAs and Si substrates was performed. Variable‐temperature photoluminescence (PL) and carrier lifetime measurements were carried out on as‐grown films and films subjected to post‐growth annealings. Films grown on GaAs substrates appeared to be mostly free from defects providing energy states within the bandgap, yet specific acceptor states were generated in these films under conditions associated with mercury deficiency. The properties of films grown on Si substrates were mostly governed by two types of uncontrolled defects. Relatively deep levels with energy 40 to 70 meV were revealed with the use of PL measurements, yet their effect on the lifetime was not traced. The lifetime value was rather determined by other type of defects with energy depth of ∼30 meV. Possible relation of these defects to the specifics of MBE growth of HgCdTe on Si substrates is discussed. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-02-03T06:40:17.545016-05:
DOI: 10.1002/pssc.201510232

• Application of the difference spectroscopy for studying of complex
acceptors in CdTe
• Authors: Victor Bagaev; Vladimir Krivobok, Sergey Nikolaev, Evgeny Onischenko, Anna Pruchkina
Pages: 477 - 480
Abstract: Wavelength modulation of the excitation source combined with the analysis of the differential PL signal have been applied to studying of electronic spectra of acceptors in compensated CdTe:Cl, CdTe:Ag,Cl single crystals. For the Cl‐related complex acceptor with an activation energy of ∼121 meV (A‐center), the energies of eight excited states are measured. In the case of tetrahedral AgCdacceptor the splitting of 2P3/2 (Γ8) and 2S3/2 (Γ8) states has been revealed for AgCd centres located at a short distances (5‐7 nm) from a hydrogen‐like donor (ClTe). A method allowing a simple symmetry test for acceptors in a diverse zinc‐blende compound semiconductor is proposed. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-02-09T02:40:11.888378-05:
DOI: 10.1002/pssc.201510262

• Photoluminescence of high‐resistivity ZnTe crystals doped with
gallium and indium
• Authors: Satoru Seto; Kazuhiko Suzuki
Pages: 490 - 493
Abstract: We have measured photoluminescence spectra of high‐resistivity ZnTe crystals doped with gallium and indium in the wide energy range from near‐band‐edge energy to deep energy region up to 0.78 eV. In the near‐band‐edge energy, we detected a characteristic excitonic peak at 2.363 eV in both gallium and indium doped high resistivity ZnTe. By comparison with a similar PL peak observed in high resistivity CdTe, we identified the characteristic peak at 2.363 eV as emission from excitons bound to defects complex arising from a Zn vacancy and gallium or indium atoms (VZn‐2D). In lower energy range, a newly strong deep emission band near 1.0 eV has been observed for the first time in high‐resistivity ZnTe crystals. The intensity of the deep emission is two order magnitude stronger than that in undoped one. Furthermore, the intensity and peak position of the deep emission band are almost unchanged by Zn‐saturated anneal at 600‐680 °C. We specualte that this deep emission band is responsible for the high resistivity of ZnTe and prevent conversion of n‐type low resistivity. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-02-03T06:40:15.785471-05:
DOI: 10.1002/pssc.201510242

• Electron spin flip Raman spectroscopy of the diluted magnetic

• Authors: A. G. Knapp; S. Petznick, F. Jansson, M. Wiemer, M. Hetterich, F. Gebhard, S. D. Baranovskii, P. J. Klar, J. Geurts
Pages: 542 - 545
Abstract: In n‐doped (Zn,Mn)Se, the (s,d) exchange influences the ground state level of the donor‐bound electrons in an external B‐field, depending on their local Mn environment. Due to the statistical Mn arrangement, this should induce a broadening of the donor energy distribution, inducing a magneto‐resistance in transport, and also a broadening of the energy distribution of donor‐bound excitons (D0,X). We have investigated this broadening for Zn0.94Mn0.06Se:Cl (n= 4.5×1017 cm‐3) by electronic spin flip Raman spectroscopy (ESFRS) on the donor electrons. Utilizing the resonant enhancement of the ESFRS intensity upon resonance of the laser light with (D0,X), we actually observe a significant broadening of the ESFRS resonance profiles with increasing B‐field, up to 11.5 meV (FWHM) for B = 5 T. Furthermore we detect a second resonance profile contribution, whose FWHM shows a much weaker B‐field dependence. We assign this contribution to a resonance mediated by the free‐exciton (X0). Our Raman results agree very well with magneto‐transport results at the same sample. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-02-09T02:40:10.240025-05:
DOI: 10.1002/pssc.201510267

• Resonant photoluminescence of a positively charged Mn‐doped quantum
dot
• Pages: 546 - 550
Abstract: We probe the spin dynamics of an individual magnetic atom (Mn) coupled to carriers in a positively charged quantum dot using resonant photoluminescence. We demonstrate that a p‐doped CdTe/ZnTe quantum dot containing a single Mn atom forms an ensemble of optical Λ systems which can be addressed independently. Performing resonant optical pumping experiment and auto‐correlation of the resonant photoluminescence, we show that these Λ systems are connected through inefficient forbidden spin‐flips. We demonstrate that the spin dynamics of X+‐Mn under resonant excitation is mainly controlled by the electron‐Mn interaction. This coherent dynamics is directly observed in the time domain and is shown to be highly sensitive to the local strain at the Mn location. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-02-03T07:10:09.451634-05:
DOI: 10.1002/pssc.201510248

• Spin properties of localized hole and resident electron in ZnO epilayers
• Authors: Jungtaek Kim; J. Puls, S. Sadofev
Pages: 551 - 554
Abstract: The spin dynamic of the hole localized inside the donor bound exciton (D0X) and donor electrons is studied in ZnO epilayer by time‐resolved optical orientation of the D0X photoluminescence and the absorption bleaching of the spin‐sensitive D0X transition, respectively. A D0X life time of 140 ps and hole spin relaxation time of 80 ps are extracted. The comparable times allows us for an effective pumping of the donor electron spin via circularly polarized excitation. Long electron spin relaxation times in the 1 μs range are uncovered if the hyperfine interaction is suppressed by a proper longitudinal magnetic field B‖. A field strength of ≈2 mT is large enough to achieve that proving the extremely small Overhauser field BN acting on localized electrons. This is a direct result of the small abundance of magnetic nuclei interacting inside the small donor volume both specific for ZnO. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-02-03T07:10:04.6489-05:00
DOI: 10.1002/pssc.201510292

• Magnetic phase transitions in ZnO doped by transition metals
• Authors: Shavkat Yuldashev; Vadim Yalishev, Ziyodbek Yunusov, Younghae Kwon, Tae Won Kang
Pages: 559 - 563
Abstract: In this work we present the results on experimental study of magnetic phase transitions in ZnO thin films doped by Mn and Co by using the thermal diffusivity and specific heat measurements. The inverted lambda‐shaped peaks observed in the temperature dependencies of the thermal diffusivity demonstrate the existence of the second order phase transitions in these samples. The magnetic entropy derived from the specific heat gives the number of magnetic ions involved in the magnetic ordering. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-02-09T02:40:16.367901-05:
DOI: 10.1002/pssc.201510221

• Annealing of frozen‐in defects in ZnO
• Pages: 590 - 593
Abstract: High temperature electrical conductivity (HTEC) as a function of time after step‐like change of Zn vapor pressure (PZn) at fixed ZnO crystal temperature (TZnO) and after step‐like change of TZnO at fixed PZn was measured in undoped ZnO single crystal and in undoped ZnO ceramic sample. It was found a difference on HTEC relaxation curves in these measurements. Samples were cooled from temperature 1273 K to room temperature. Appearance of asymmetric spectrum with g≈1.96 and disappearance of Mn2+ spectrum were detected in EPR investigations. Then vacuum annealing was applied for these samples and intensity of g≈1.96 EPR spectrum was registered after every vacuum annealing cycles. The change in sample color, the change in g≈1.96 spectrum intensity as well as appearance again of Mn2+ EPR spectrum in the course of vacuum annealing was explained by the model of defect clusters formed during cooling of the crystal. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-02-03T06:40:11.66814-05:0
DOI: 10.1002/pssc.201510244

• Defect related emission of ZnO and ZnO Cu nanocrystals prepared by
electrochemical method
• Pages: 594 - 597
Abstract: Photoluminescence (PL), its temperature dependence, and SEM images have been applied for the comparative study of the ZnO and ZnO Cu nanocrystals (NCs). NCs were created by the electrochemical (anodization) method with different NC sizes and annealed at 400 °C for 2 hours in ambient air. PL spectra show a near band edge (NBE) emission and three defect‐related PL bands in ZnO NCs, and four defect‐related PL bands in ZnO Cu NCs. The defect related PL band with the peak at 2.60‐2.70 eV is connected with the Cu complexes in ZnO Cu NCs. PL spectra of all PL bands in both NC types were studied in the temperature range 10‐300 K. Their integrated PL intensities and the activation energies of PL thermal decays have been estimated. It is shown that the PL intensities of defect related PL bands have been stimulated essentially at doping by the small Cu concentration (2.2%) in ZnO Cu NCs. It is revealed additionally that the Cu doping leads to decreasing the activation energies of thermal decay for the defect related PL bands in ZnO Cu NCs in comparison with those in ZnO NCs. The physical reason of this effect and the mechanisms of optical transitions for defect related PL bands in ZnO NCs have been discussed. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-02-03T07:10:06.711892-05:
DOI: 10.1002/pssc.201510277

• Anisotropic optical properties of a homoepitaxial (Zn,Mg)O/ZnO quantum
well grown on a‐plane ZnO substrate
• Authors: Mohammed J. Mohammed Ali; J.M. Chauveau, T. Bretagnon
Pages: 598 - 601
Abstract: The optical properties of homoepitaxial non‐polar (Zn,Mg)O/ZnO single quantum wells (QWs) grown by molecular beam epitaxy on a‐plane (11‐20) ZnO substrates are investigated by using reflectance and continuous wave photoluminescence spectroscopies. The reflectivity and CW‐PL spectra measured at low temperature reveal strong in‐plane optical anisotropies and clear reflectance structures. The signatures of confined excitons analogous to C‐exciton and (A, B)‐excitons in bulk ZnO, are detected using light polarized respectively along the c‐axis and perpendicular to this axis. Temperature dependence of CW‐PL has been investigated in the two polarizations. For electric field of the light perpendicular to the c‐axis the total intensity of the PL lines decreases by about an order of magnitude when the temperature increases from 8 K to room temperature. At low temperature a line associated to an excitonic complex dominates the PL spectrum. When the temperature increases the intensity of this line decreases as the intensity of the line associated to the free exciton increases. In the other polarization for temperature above 100 K a new line appears in the spectrum. Its intensity increases with temperature. This feature is associated to the c‐like free exciton. The degree of polarization of these lines is independent of temperature. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-02-03T06:40:16.654959-05:
DOI: 10.1002/pssc.201510238

• Quantum confined Stark effect of polar and non‐polar ZnO/ZnMgO
quantum wells grown by MBE
• Authors: Tomoki Abe; Tatsuya Motoyama, Masaya Yamamoto, Atsushi Yamamoto, Shohei Iwagashita, Hirofumi Kasada, Koshi Ando, Kunio Ichino
Pages: 602 - 605
Abstract: We have investigated quantum confined Stark effects of polar (O‐polar) and non‐polar ZnO/ZnMgO quantum wells (QWs) by electroabsorption (EA) spectroscopy. The ZnO/ZnMgO QWs were grown by plasma assisted molecular beam epitaxy (PA‐MBE). The ZnO/ZnMgO QWs were grown on c‐plane sapphire for polar ZnO QWs, and on r‐plane sapphire for non‐polar ZnO QWs, respectively. The polar ZnO/ZnMgO QWs exhibited a blue‐shift of 20 meV in excitonic transition energy by applying external bias at room temperature. This blue‐shift is due to reverse quantum confined Stark effect (QCSE) in a piezo electric‐field induced QW structures of wurtzite ZnO/ZnMgO QWs with c‐axis orientation. We confirmed a large red‐shift of 29 meV for non‐polar ZnO/ZnMgO QWs. This energy shift is originated from normal QCSE in the flat potential QWs without built‐in piezo electric‐field. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-02-03T07:10:07.589609-05:
DOI: 10.1002/pssc.201510272

• Gamma‐ray tolerance of CdS/CdTe photodiodes for radiation tolerant
compact image sensor with field emitter array
• Authors: Tamotsu Okamoto; Tomoya Igari, Yasuhito Gotoh, Nobuhiro Sato, Masafumi Akiyoshi, Ikuji Takagi
Pages: 635 - 638
Abstract: The effect of gamma irradiation on two types (superstrate‐ and substrate‐type) of CdS/CdTe photodiodes, which we have proposed as potential photoconducting films for compact image sensors with a field emitter array (FEA), was investigated. A 60Co gamma‐ray source was employed, and the total gamma irradiation dose was more than 500 kGy. For the superstrate‐type structure, the irradiation caused the short‐circuit current density (JSC) to decrease, probably due to the resulting decreased transmittance of the glass substrate. On the other hand, little degradation of the I ‐V characteristics or spectral response was observed after the gamma irradiation for the substrate‐type structure. These results suggest that, taking into account the decrease in transmittance of the glass substrate, the CdS/CdTe photodiodes have sufficient tolerance to high gamma‐ray exposure. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-02-03T06:40:19.140073-05:
DOI: 10.1002/pssc.201510229

• Multi‐band radiation detector based on HgCdTe heterostructure
• Authors: T. Kryshtab; R. K. Savkina, A. B. Smirnov, M. Kladkevich, V. Samoylov
Pages: 639 - 642
Abstract: We describe multi‐band radiation detector based on HgCdTe/Si heterostructure, which exhibits sensitivity in the MWIR and LWIR spectral range without cryogenic cooling to achieve useful performance. The noise equivalent power (NEP) for one of the detectors studied reached NEP296 K= 3.8×10‐13W/Hz1/2. HgCdTe‐based heterostructure is also considered as sub‐THz detector. The sensitivity of HgCdTe‐based heterostructure for sub‐THz radiation was found after the oblique‐incidence (45°) bombardment with silver ions (140 keV). The signal was detected without antenna and amplification and NEP at ν≈140 GHz and 296 K reaches 4.5×10‐8W/Hz1/2. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-02-03T07:10:05.804674-05:
DOI: 10.1002/pssc.201510278

• Application of indium tin oxide to the p‐cladding layers of
yellow/green II‐VI compound semiconductor laser diode structures on
InP substrates
• Authors: Koji Fukushima; Tomohiro Shiraishi, Ryohei Kobayashi, Katsumi Kishino, Ichirou Nomura
Pages: 665 - 668
Abstract: The application of indium tin oxide (ITO) as the p‐cladding layer of II‐VI compound semiconductor laser diodes (LDs) on InP substrates was investigated. The waveguide analysis of the LD structures revealed that the optical confinement effect around the active layer was obviously improved by changing the p‐cladding layer from the conventional MgSe/BeZnTe superlattice to ITO. For example, the estimated optical confinement factors were 0.15 and 0.27 for the conventional and ITO LD structure, respectively, when the emission wavelength was 580 nm. In addition, we investigated optimum LD structures, considering the optical and carrier confinements at the active layer. In experiments, light emitting devices with an ITO layer were fabricated on InP substrates via molecular beam epitaxy and radio‐frequency (RF) magnetron sputtering. Yellow emissions at 582 nm were observed by current injections at room temperature. These results indicate that ITO is a promising p‐cladding layer material for II‐VI LDs on InP substrates. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-02-09T02:40:13.832463-05:
DOI: 10.1002/pssc.201510254

• Growth and characterization of ZnCdSe/ZnCdMgSe two‐color quantum
well infrared photodetectors
• Authors: Guopeng Chen; Yasin Kaya, Arvind Pawan Ravikumar, Maria C. Tamargo, Claire F. Gmachl, Aidong Shen
Pages: 673 - 676
Abstract: The authors report, for the first time, the new two‐color quantum well infrared photodetectors (QWIPs) from a non‐III‐V semiconductor material system. The samples were grown on InP substrate by molecular beam epitaxy. X‐ray diffraction and photoluminescence measurements showed high structural and optical quality of the samples. Two intersubband (ISB) absorption peaks in two different wavelength regions are observed in Fourier transform infrared measurements. The two‐color photodetectors can be turned on separately or simultaneously in the two spectral regions. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PubDate: 2016-02-09T02:40:12.681193-05:
DOI: 10.1002/pssc.201510257

• Numerical analysis of light elements transport in a unidirectional
solidification furnace
• Authors: Koichi Kakimoto; Bing Gao, Satoshi Nakano
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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