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ENGINEERING (1206 journals)                  1 2 3 4 5 6 7 | Last

Showing 1 - 200 of 1205 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 7)
3D Research     Hybrid Journal   (Followers: 19)
AAPG Bulletin     Hybrid Journal   (Followers: 6)
AASRI Procedia     Open Access   (Followers: 15)
Abstract and Applied Analysis     Open Access   (Followers: 3)
Aceh International Journal of Science and Technology     Open Access   (Followers: 2)
ACS Nano     Full-text available via subscription   (Followers: 233)
Acta Geotechnica     Hybrid Journal   (Followers: 7)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 2)
Acta Scientiarum. Technology     Open Access   (Followers: 3)
Acta Universitatis Cibiniensis. Technical Series     Open Access  
Active and Passive Electronic Components     Open Access   (Followers: 7)
Adaptive Behavior     Hybrid Journal   (Followers: 11)
Adıyaman Üniversitesi Mühendislik Bilimleri Dergisi     Open Access  
Adsorption     Hybrid Journal   (Followers: 4)
Advanced Engineering Forum     Full-text available via subscription   (Followers: 6)
Advanced Science     Open Access   (Followers: 5)
Advanced Science Focus     Free   (Followers: 3)
Advanced Science Letters     Full-text available via subscription   (Followers: 7)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 7)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 17)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 5)
Advances in Complex Systems     Hybrid Journal   (Followers: 7)
Advances in Engineering Software     Hybrid Journal   (Followers: 25)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 15)
Advances in Fuzzy Systems     Open Access   (Followers: 5)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 10)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 21)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 9)
Advances in Natural Sciences: Nanoscience and Nanotechnology     Open Access   (Followers: 28)
Advances in Operations Research     Open Access   (Followers: 11)
Advances in OptoElectronics     Open Access   (Followers: 5)
Advances in Physics Theories and Applications     Open Access   (Followers: 12)
Advances in Polymer Science     Hybrid Journal   (Followers: 41)
Advances in Porous Media     Full-text available via subscription   (Followers: 4)
Advances in Remote Sensing     Open Access   (Followers: 37)
Advances in Science and Research (ASR)     Open Access   (Followers: 6)
Aerobiologia     Hybrid Journal   (Followers: 1)
African Journal of Science, Technology, Innovation and Development     Hybrid Journal   (Followers: 4)
AIChE Journal     Hybrid Journal   (Followers: 30)
Ain Shams Engineering Journal     Open Access   (Followers: 5)
Akademik Platform Mühendislik ve Fen Bilimleri Dergisi     Open Access  
Alexandria Engineering Journal     Open Access   (Followers: 1)
AMB Express     Open Access   (Followers: 1)
American Journal of Applied Sciences     Open Access   (Followers: 28)
American Journal of Engineering and Applied Sciences     Open Access   (Followers: 11)
American Journal of Engineering Education     Open Access   (Followers: 9)
American Journal of Environmental Engineering     Open Access   (Followers: 16)
American Journal of Industrial and Business Management     Open Access   (Followers: 23)
Analele Universitatii Ovidius Constanta - Seria Chimie     Open Access  
Annals of Combinatorics     Hybrid Journal   (Followers: 3)
Annals of Pure and Applied Logic     Open Access   (Followers: 2)
Annals of Regional Science     Hybrid Journal   (Followers: 7)
Annals of Science     Hybrid Journal   (Followers: 7)
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2)
Applicable Analysis: An International Journal     Hybrid Journal   (Followers: 1)
Applied Catalysis A: General     Hybrid Journal   (Followers: 6)
Applied Catalysis B: Environmental     Hybrid Journal   (Followers: 15)
Applied Clay Science     Hybrid Journal   (Followers: 5)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 12)
Applied Magnetic Resonance     Hybrid Journal   (Followers: 4)
Applied Nanoscience     Open Access   (Followers: 8)
Applied Network Science     Open Access  
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Physics Research     Open Access   (Followers: 3)
Applied Sciences     Open Access   (Followers: 2)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 4)
Arabian Journal for Science and Engineering     Hybrid Journal   (Followers: 5)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 4)
Archives of Foundry Engineering     Open Access  
Archives of Thermodynamics     Open Access   (Followers: 7)
Arkiv för Matematik     Hybrid Journal   (Followers: 1)
ASEE Prism     Full-text available via subscription   (Followers: 3)
Asian Engineering Review     Open Access  
Asian Journal of Applied Science and Engineering     Open Access   (Followers: 1)
Asian Journal of Applied Sciences     Open Access   (Followers: 2)
Asian Journal of Biotechnology     Open Access   (Followers: 8)
Asian Journal of Control     Hybrid Journal  
Asian Journal of Current Engineering & Maths     Open Access  
Asian Journal of Technology Innovation     Hybrid Journal   (Followers: 8)
Assembly Automation     Hybrid Journal   (Followers: 2)
at - Automatisierungstechnik     Hybrid Journal   (Followers: 1)
ATZagenda     Hybrid Journal  
ATZextra worldwide     Hybrid Journal  
Australasian Physical & Engineering Sciences in Medicine     Hybrid Journal   (Followers: 1)
Australian Journal of Multi-Disciplinary Engineering     Full-text available via subscription   (Followers: 2)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 8)
Avances en Ciencias e Ingeniería     Open Access  
Balkan Region Conference on Engineering and Business Education     Open Access   (Followers: 1)
Bangladesh Journal of Scientific and Industrial Research     Open Access  
Basin Research     Hybrid Journal   (Followers: 5)
Batteries     Open Access   (Followers: 4)
Bautechnik     Hybrid Journal   (Followers: 1)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 23)
Beni-Suef University Journal of Basic and Applied Sciences     Open Access   (Followers: 4)
BER : Manufacturing Survey : Full Survey     Full-text available via subscription   (Followers: 2)
BER : Motor Trade Survey     Full-text available via subscription   (Followers: 1)
BER : Retail Sector Survey     Full-text available via subscription   (Followers: 2)
BER : Retail Survey : Full Survey     Full-text available via subscription   (Followers: 2)
BER : Survey of Business Conditions in Manufacturing : An Executive Summary     Full-text available via subscription   (Followers: 3)
BER : Survey of Business Conditions in Retail : An Executive Summary     Full-text available via subscription   (Followers: 3)
Bharatiya Vaigyanik evam Audyogik Anusandhan Patrika (BVAAP)     Open Access   (Followers: 1)
Biofuels Engineering     Open Access  
Biointerphases     Open Access   (Followers: 1)
Biomaterials Science     Full-text available via subscription   (Followers: 10)
Biomedical Engineering     Hybrid Journal   (Followers: 16)
Biomedical Engineering and Computational Biology     Open Access   (Followers: 13)
Biomedical Engineering Letters     Hybrid Journal   (Followers: 5)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 17)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 31)
Biomedical Engineering: Applications, Basis and Communications     Hybrid Journal   (Followers: 5)
Biomedical Microdevices     Hybrid Journal   (Followers: 9)
Biomedical Science and Engineering     Open Access   (Followers: 4)
Biomedizinische Technik - Biomedical Engineering     Hybrid Journal  
Biomicrofluidics     Open Access   (Followers: 4)
BioNanoMaterials     Hybrid Journal   (Followers: 2)
Biotechnology Progress     Hybrid Journal   (Followers: 39)
Boletin Cientifico Tecnico INIMET     Open Access  
Botswana Journal of Technology     Full-text available via subscription  
Boundary Value Problems     Open Access   (Followers: 1)
Brazilian Journal of Science and Technology     Open Access   (Followers: 2)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 10)
Bulletin of Canadian Petroleum Geology     Full-text available via subscription   (Followers: 14)
Bulletin of Engineering Geology and the Environment     Hybrid Journal   (Followers: 3)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Cahiers, Droit, Sciences et Technologies     Open Access  
Calphad     Hybrid Journal  
Canadian Geotechnical Journal     Hybrid Journal   (Followers: 14)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 41)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 8)
Case Studies in Thermal Engineering     Open Access   (Followers: 3)
Catalysis Communications     Hybrid Journal   (Followers: 6)
Catalysis Letters     Hybrid Journal   (Followers: 2)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 8)
Catalysis Science and Technology     Free   (Followers: 6)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysis Today     Hybrid Journal   (Followers: 8)
CEAS Space Journal     Hybrid Journal  
Cellular and Molecular Neurobiology     Hybrid Journal   (Followers: 3)
Central European Journal of Engineering     Hybrid Journal   (Followers: 1)
CFD Letters     Open Access   (Followers: 6)
Chaos : An Interdisciplinary Journal of Nonlinear Science     Hybrid Journal   (Followers: 2)
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 3)
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 2)
Chinese Journal of Engineering     Open Access   (Followers: 2)
Chinese Science Bulletin     Open Access   (Followers: 1)
Ciencia e Ingenieria Neogranadina     Open Access  
Ciencia en su PC     Open Access   (Followers: 1)
Ciencias Holguin     Open Access   (Followers: 1)
CienciaUAT     Open Access  
Cientifica     Open Access  
CIRP Annals - Manufacturing Technology     Full-text available via subscription   (Followers: 11)
CIRP Journal of Manufacturing Science and Technology     Full-text available via subscription   (Followers: 14)
City, Culture and Society     Hybrid Journal   (Followers: 21)
Clay Minerals     Full-text available via subscription   (Followers: 10)
Clean Air Journal     Full-text available via subscription   (Followers: 2)
Coal Science and Technology     Full-text available via subscription   (Followers: 3)
Coastal Engineering     Hybrid Journal   (Followers: 11)
Coastal Engineering Journal     Hybrid Journal   (Followers: 5)
Coatings     Open Access   (Followers: 3)
Cogent Engineering     Open Access   (Followers: 2)
Cognitive Computation     Hybrid Journal   (Followers: 4)
Color Research & Application     Hybrid Journal   (Followers: 1)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 13)
Combustion, Explosion, and Shock Waves     Hybrid Journal   (Followers: 13)
Communications Engineer     Hybrid Journal   (Followers: 1)
Communications in Numerical Methods in Engineering     Hybrid Journal   (Followers: 2)
Components, Packaging and Manufacturing Technology, IEEE Transactions on     Hybrid Journal   (Followers: 26)
Composite Interfaces     Hybrid Journal   (Followers: 6)
Composite Structures     Hybrid Journal   (Followers: 258)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 180)
Composites Part B : Engineering     Hybrid Journal   (Followers: 236)
Composites Science and Technology     Hybrid Journal   (Followers: 215)
Comptes Rendus Mécanique     Full-text available via subscription   (Followers: 2)
Computation     Open Access  
Computational Geosciences     Hybrid Journal   (Followers: 14)
Computational Optimization and Applications     Hybrid Journal   (Followers: 7)
Computational Science and Discovery     Full-text available via subscription   (Followers: 2)
Computer Applications in Engineering Education     Hybrid Journal   (Followers: 6)
Computer Science and Engineering     Open Access   (Followers: 17)
Computers & Geosciences     Hybrid Journal   (Followers: 28)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 5)
Computers and Electronics in Agriculture     Hybrid Journal   (Followers: 4)
Computers and Geotechnics     Hybrid Journal   (Followers: 10)
Computing and Visualization in Science     Hybrid Journal   (Followers: 5)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 30)
Conciencia Tecnologica     Open Access  
Concurrent Engineering     Hybrid Journal   (Followers: 3)
Continuum Mechanics and Thermodynamics     Hybrid Journal   (Followers: 6)
Control and Dynamic Systems     Full-text available via subscription   (Followers: 9)
Control Engineering Practice     Hybrid Journal   (Followers: 42)
Control Theory and Informatics     Open Access   (Followers: 8)
Corrosion Science     Hybrid Journal   (Followers: 25)
CT&F Ciencia, Tecnologia y Futuro     Open Access  
CTheory     Open Access  
Current Applied Physics     Full-text available via subscription   (Followers: 4)
Current Science     Open Access   (Followers: 58)

        1 2 3 4 5 6 7 | Last

Journal Cover Current Applied Physics
  [SJR: 0.716]   [H-I: 55]   [4 followers]  Follow
   Full-text available via subscription Subscription journal
   ISSN (Print) 1567-1739
   Published by Elsevier Homepage  [3044 journals]
  • Trap states analysis in AlGaN/AlN/GaN and InAlN/AlN/GaN high electron
           mobility transistors
    • Abstract: Publication date: December 2017
      Source:Current Applied Physics, Volume 17, Issue 12
      Author(s): S. Latrach, E. Frayssinet, N. Defrance, S. Chenot, Y. Cordier, C. Gaquière, H. Maaref
      The paper deals with trap effects in InAlN/AlN/GaN and AlGaN/AlN/GaN high electron mobility transistor structures using frequency dependent conductance and High-Low frequency capacitance analysis. We performed a comparative study on electrical characteristics of electron devices. Capacitance-voltage characteristics revealed hysteresis with a voltage shift that was attributed to the accumulation of charges at the InAlN/AlN and AlGaN/AlN heterointerfaces. Using a simple extraction method, a rather low density of trapped charges is evaluated. On the other hand, bias and frequency dependent measurements are carried out in the vicinity of threshold voltage to determine the interface trap density Dit, trap time constant τit and trap state energy position ET. It is found that device with InAlN barrier exhibits high trap state densities in the range of 1012 -1014 cm−2eV−1, approximately one order of magnitude larger than with AlGaN barrier.

      PubDate: 2017-09-19T02:37:14Z
  • Enhanced thermoelectric performance of n-type bismuth selenide doped with
    • Abstract: Publication date: December 2017
      Source:Current Applied Physics, Volume 17, Issue 12
      Author(s): Chiranjit Kulsi, Kajari Kargupta, Saibal Ganguly, Dipali Banerjee
      Bismuth selenide (Bi2Se3) and transition metal (nickel) doped (5 and 7.5 mol %) Bi2Se3 have been prepared by solvothermal approach for investigation of thermoelectric properties of the materials. The morphological characterization reveals plate and flake like structures for undoped and doped samples respectively. There is a decrease in lattice constant, computed from Rietveld refinement data and crystallite size, found using Debye-Scherrer equation for doped samples. Doping by nickel increases the electrical conductivity and reduces both thermo power and thermal conductivity of the materials than pure Bi2Se3. Reduction in thermal conductivity of the doped samples by 42%, results in an increase in figure of merit (ZT) of nickel doped (5%) materials by one order of magnitude (0.02–0.22) compared to pure Bi2Se3.
      Graphical abstract image

      PubDate: 2017-09-19T02:37:14Z
  • Enhanced quantum confinement in tensile-strained silicon nanocrystals
           embedded in silicon nitride
    • Abstract: Publication date: December 2017
      Source:Current Applied Physics, Volume 17, Issue 12
      Author(s): Chang-Hee Cho, Jang-Won Kang, Il-Kyu Park, Seong-Ju Park
      Here, we report that the tensile strain in silicon nanocrystals embedded in silicon nitride significantly changes the size-dependent evolution of the conduction and valence energy levels, compared with strain-free silicon nanocrystals. Using capacitance spectroscopy, the quantum-confined energy shifts in the conduction and valence levels were identified as ΔE C (eV) = 11.7/d 2 , and ΔE V (eV) = −4.5/d 2 , where d is the mean diameter of the silicon nanocrystals in nanometers. These findings indicated that the tensile strain in the silicon nanocrystals significantly increased the quantum confinement, by a factor of 3.3 in the conduction levels, and by a factor of 1.8 in the valence levels.

      PubDate: 2017-09-19T02:37:14Z
  • Magnetic domain wall motion across a step of Dzyaloshinskii-Moriya
    • Abstract: Publication date: December 2017
      Source:Current Applied Physics, Volume 17, Issue 12
      Author(s): Ik-Sun Hong, Seo-Won Lee, Kyung-Jin Lee
      Magnetic domain wall motion is numerically studied in a nanowire with a Dzyaloshinskii-Moriya interaction (DMI) step at which DMI varies in real space. The spatially modulated DMI results in the formation of asymmetric domain wall energy landscape across the step, which affects the domain wall motion significantly. Utilizing this DMI step, we propose a domain wall memory device where the switching of up- and down-state is induced by a spin-orbit spin-transfer torque (SOT)-driven domain wall motion. This domain wall memory device is expected to have a high switching efficiency.

      PubDate: 2017-09-12T02:09:35Z
  • Effect of beryllium doping and vacancy in band structure, magnetic and
           optical properties of free standing germanene
    • Abstract: Publication date: December 2017
      Source:Current Applied Physics, Volume 17, Issue 12
      Author(s): Namrata Dhar, Debnarayan Jana
      Ab initio calculations of electronic, magnetic and optical properties of defected (beryllium (Be) doped or void induced) buckled free standing (FS) germanene have been explored. Concentrations of doping as well as vacancy (keeping a fixed low amount of Be) are increased thoroughly, in order to study the modifications of different physical properties critically. Our study reveals that, incorporation of doping and void destroy Dirac cone in band structure of germanene. Finite bandgap for the requirement of field effect transistor (FET) applications is obtained in case of semiconducting configuration with 15.62% doping concentration. Magnetism is also induced for doping of Be with high concentration only, which is supported from projected density of states (PDOS) and charge density analysis. Anisotropic effects are prominent in optical properties like dielectric functions, absorption spectra, reflectivity and its modulation and conductivity. Static real part of dielectric constant increases linearly with increase in doping concentration but decreases with increase in vacancy concentration considering parallel polarization of electro-magnetic (EM) wave. Predicted computational results of plasma frequencies are in well agreement with expected analytical data. Peak corresponding to maximum intensity of electron energy loss spectra (EELS) appears at the position of plasma frequency in case of every structure. We expect, this study may help for better understanding of next generation germanene based nano-technology.

      PubDate: 2017-09-12T02:09:35Z
  • A comparative study of the mechanical properties of multilayer MoS2 and
           graphene/MoS2 heterostructure: effects of temperature, number of layers
           and stacking order
    • Abstract: Publication date: November 2017
      Source:Current Applied Physics, Volume 17, Issue 11
      Author(s): Nayereh Ghobadi
      In this paper molecular dynamic simulation is used to examine the mechanical properties of multilayer molybdenum disulfide (MoS2) and graphene/MoS2 heterostructure under uniaxial tensile and normal compressive strain. The effects of temperature, layer number and stacking order of layers on the stress-strain curve and elastic properties are studied. We find that the Young's modulus and vertical elastic constant of the heterostructure are much larger than that of MoS2 which is due to the higher stiffness and Young's modulus of graphene compared to MoS2. Furthermore, the results reveal that graphene/MoS2 heterostructure is more resistant to the variation of temperature. While the rise in temperature results in the decrease of elastic constants, fracture strain and fracture stress of both structures, the increase in the number of layers only affects the elastic properties of heterostructure and has little influence on the stiffness of multilayer MoS2. Our simulations also illustrate that the highest energy stacking orders, AA3 and AB3, wherein S atoms of top layer are located above the S atoms of bottom layer, have the lowest elastic constants among all structures.

      PubDate: 2017-09-12T02:09:35Z
  • Mechanism of the formation of the structure and phase state of binary
           metallic nanoparticles obtained by the electric explosion of two wires
           made of different metals
    • Abstract: Publication date: November 2017
      Source:Current Applied Physics, Volume 17, Issue 11
      Author(s): Alexander Pervikov, Marat Lerner
      Based on the statistical approach to the description of the structure of liquid metals, it has been shown that during wire heating with a current pulse, the drastic local increase in the electric resistance of the liquid metal leads to the development of overheating instability. The increase in the electric resistance of the liquid metal is a consequence of the destruction of individual atom clusters that form short range order in the liquid metal. Non-uniform heating leads to the transition of liquid metal into a two-phase “gas-liquid” state formed by the expanding products of the explosion of wires. The majority of the expanding wire explosion products are liquid phase particles; those coagulate to form a binary melt. It has been shown by the example of Pb/Al, Ag/Cu and Cu/Al nanoparticles forming during the electric explosion of two wires made of different metals that the structure and phase state of the particles is determined by the probability of the formation of the binary melt that depends on the temperature of the coagulating particles.

      PubDate: 2017-09-12T02:09:35Z
  • Electric-field-induced evolution of domain shapes in polarization reversal
           of BiFeO3 (111) capacitors
    • Abstract: Publication date: November 2017
      Source:Current Applied Physics, Volume 17, Issue 11
      Author(s): Tae Heon Kim
      Relying on an external electric field, the shape of propagating domains evolves in polarization switching of ferroelectric BiFeO3 (111) capacitors. With an increasing negative switching bias, it is shown that the domain pattern during ferroelectric domain growth evolves from a circular shape to a dendrite-like shape. Electrical current measurements for different poling states reveal that holes are easily injected through the BiFeO3/SrRuO3 interface under a negative voltage bias. It is found that holes injected by large negative-switching-pulse fields facilitate domain nucleation in BiFeO3 (111) films and thereby, the promoted domain nucleation drives the shape of switched domains to be dendrite-like.

      PubDate: 2017-09-12T02:09:35Z
  • Controllable synthesis and visible-active photocatalytic properties of Au
           nanoparticles decorated urchin-like ZnO nanostructures
    • Abstract: Publication date: November 2017
      Source:Current Applied Physics, Volume 17, Issue 11
      Author(s): Chi H. Le, Oanh T.T. Nguyen, Hieu S. Nguyen, Long D. Pham, Chung V. Hoang
      Urchin-like nanostructures of ZnO were synthesized by one-step hydrothermal method and their morphology was optimized via the hydrothermal temperature - the key parameter in controlling the morphologies of the ZnO materials. The photoabsorbance of the urchin-like ZnO nanomaterials was expanded from the intrinsic UV absorption range to the visible region by depositing the plasmonic Au nanoparticles (AuNPs) on the ZnO surface. The synthesized visible-active AuNPs-ZnO urchin-like composite material showed an excellent photocatalytic activity. As a result of the shape effect, the impact of the AuNPs on the photocatalytic activity of the urchin-like ZnO is found to increase about 30% in comparison to that of the reported conventional ZnO nanorods.

      PubDate: 2017-09-12T02:09:35Z
  • Studies of magnetic dipolar interaction between individual atoms using
    • Abstract: Publication date: November 2017
      Source:Current Applied Physics, Volume 17, Issue 11
      Author(s): Taeyoung Choi, Christopher P. Lutz, Andreas J. Heinrich
      Sensing magnetic interactions at the atomic scale and utilizing those interactions for magnetometry have been highly challenging and important topics in the magnetic resonance community. Recently, electron spin resonance and scanning tunneling microscopy (ESR-STM) have been successfully combined, enabling spin resonance of individual atoms on ultrathin insulating MgO surfaces. When two magnetic atoms are positioned within the separation range of 1 nm–4 nm, two spectral features appear in the ESR measurement. The difference in those two frequencies follows a r − 3 distance-dependence, indicating that the individual atoms are coupled through the magnetic dipolar interaction. Here, we discuss the spin relaxation times that lead to the observed ESR spectra. In addition, we suggest a quantum Hamiltonian model to obtain further insights toward, for example, studies of frustrated spin systems.

      PubDate: 2017-09-12T02:09:35Z
  • Structural and dielectric properties of NaIO4 – Complexed PEO/PVP
           blended solid polymer electrolytes
    • Abstract: Publication date: November 2017
      Source:Current Applied Physics, Volume 17, Issue 11
      Author(s): H.K. Koduru, L. Marino, F. Scarpelli, A.G. Petrov, Y.G. Marinov, G.B. Hadjichristov, M.T. Iliev, N. Scaramuzza
      Poly (ethylene oxide) (PEO)/Polyvinyl pyrrolidone (PVP) blended solid polymer electrolytes complexed with NaIO4 salt at different weight percentage ratios were prepared using solution casting technique. Effect of salt complexation on structural properties of pure blend (PEO/PVP) electrolyte was investigated by X-ray diffraction (XRD), Raman spectroscopy and Scanning electron microscopic (SEM) studies. Modifications in glass transition temperature and thermal stability of the blend electrolytes were measured by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) studies. The determined refractive index values from optical absorption spectra were found to increase with the increase of salt concentration. Impedance measurements were made in the frequency range of 0.1 Hz–1 MHz to explore dielectric response and ion dynamics of the blend electrolytes as a function of NaIO4 salt concentration. The PEO/PVP blend complexed with 10 wt% of NaIO4 salt was demonstrated higher room temperature conductivity of 1.56 × 10−7 S/cm. The temperature dependence of DC conductivity of blend electrolytes was followed the Arrhenius behaviour. Determined diffusion coefficients (DNa+) using Trukhan model and estimated mobility (μ) values of sodium ions were increased with increase of salt concentration. To get the further insights into the ion dynamics, the complex dielectric permittivity has been modeled with Havriliak–Negami function.

      PubDate: 2017-09-12T02:09:35Z
  • Negative magnetoresistance in sputtered niobium thin films grown on
           silicon substrates
    • Abstract: Publication date: November 2017
      Source:Current Applied Physics, Volume 17, Issue 11
      Author(s): T.C. Freitas, J.L. Gonzalez, V.P. Nascimento, A.Y. Takeuchi, E.C. Passamani
      Nb-films (thicknesses of 20 nm, 50 nm and 100 nm), directly grown on orientated Si substrates by DC sputtering, have shown reduced superconducting critical temperatures T C as compared to the bulk value; an effect associated with their disordered granular character (the disorder phenomenon of the Nb-films depresses the density of states at the Fermi level, consequently shifts the T C value towards low temperatures). The disorder effect was also correlated to the semiconducting-like behavior observed in the R ( T ) measurements. At the normal state, while the 100 nm Nb-film is dominated by a metallic-like behavior, the thinner Nb-films (20 nm and 50 nm thick) show significant negative magnetoresistances in a small temperature range about T C . This behavior was also explained assuming their granular characters, where the applied magnetic field first destroys the global superconducting character of the Nb-films, leaving Cooper pairs localized inside Nb-grains. A further increase of the applied field strength affects the superconductivity inside Nb-grains, enhancing the normal intergranular electric transport channel, which decreases the whole resistance of the Nb-films. The present study suggests that the microscopic disorder, at the grain surfaces/interfaces, seems to be an essential point to comprehend the negative magnetoresistance effect observed in some superconducting granular systems.

      PubDate: 2017-09-12T02:09:35Z
  • First principles investigations of electronics, magnetic, and
           thermoelectric properties of rare earth based PrYO3(Y=Cr, V) perovskites
    • Abstract: Publication date: November 2017
      Source:Current Applied Physics, Volume 17, Issue 11
      Author(s): B. Sabir, G. Murtaza, Q. Mahmood, R. Ahmad, K.C. Bhamu
      The structural, electronic, magnetic, optical and thermoelectric properties of PrYO3(Y=Cr, V) have been studied by using density functional based FP-LAPW+ lo method as implemented into WIEN2k code. The analysis of band structures and density of states confirm the half metallic ferromagnetism in studied compounds. The nature and origin of ferromagnetism has been depicted in terms of crystal field energies, exchange energies involved and exchange constants. Moreover, the reduction of magnetic moment from V/Cr, Pr sites and generation of small magnetic moments on oxygen and interstitials sites leads to negative value of indirect exchange energy Δx(pd) and strong hybridization. Finally, the thermoelectric behavior has been explained by discussing the electrical conductivity, thermal conductivity, Seebeck coefficient, power factor and thermal efficiency. Moreover, evaluation of PrYO3 on the basis of its magnetic and thermoelectric properties conform that the compounds are much suitable for spintronic and thermoelectric applications.

      PubDate: 2017-09-12T02:09:35Z
  • The mechanism of enhanced photocatalytic activity of SnO2 through
           fullerene modification
    • Abstract: Publication date: November 2017
      Source:Current Applied Physics, Volume 17, Issue 11
      Author(s): Shuang-Shuang Ding, Wei-Qing Huang, Bing-Xin Zhou, Ping Peng, Wang-Yu Hu, Meng-Qiu Long, Gui-Fang Huang
      Carbon nanomaterials are prominent building blocks in the synthetic van der Waals (vdW) heterostructures with desired properties. Scientific understanding of their interfacial interactions is the premise to design this kind of vdW heterostructures with optimal performance. We here study the mechanism of enhanced photocatalytic activity of SnO2 by fullerene modification at electronic level, to explore the interfacial interaction and its correlation with photocatalytic activity. The results show that the interfacial interaction increases with the number of C atom of fullerene, and leads to some of C atoms be positively/negatively charged, making the fullerene a highly active co-catalyst in heterostructures. Compared to pristine SnO2, the band gap of the heterostructures is much smaller, leading to their absorption wavelength extending the entire visible region. Interestingly, a staggered type-II band alignment in the C20 (C60)/SnO2 (101) heterostructures results into the robust separation of photoexcited charge carriers between the two constituents, indicating that the fullerene is an effective sensitizer, and thus enhanced photocatalytic activity. These findings can rationalize the available experiment and will be of broad interest in developing the highly efficient semiconductor photocatalysts via fullerene modification.

      PubDate: 2017-09-12T02:09:35Z
  • Photo-catalytic activity of hydrophilic-modified TiO2 for the
           decomposition of methylene blue and phenol
    • Abstract: Publication date: November 2017
      Source:Current Applied Physics, Volume 17, Issue 11
      Author(s): Byeong Jun Cha, Tae Gyun Woo, Eun Ji Park, Il Hee Kim, Jung Eun An, Hyun Ook Seo, Young Dok Kim
      We applied hydrophilic surface modification to P-25 TiO2 nanoparticles via thermal deposition of polydimethylsiloxane (PDMS), followed by annealing at 800 °C under vacuum conditions. This process yielded a thin layer consisting of hydrophilic organic functional groups (e.g., -C=O) as well as SiOx structures on the surface of TiO2. Compared to bare TiO2, the surface-modified TiO2 showed a higher adsorption capacity and photo-catalytic decomposition rate toward methylene blue. However, regarding the photo-catalytic decomposition of phenol, total mineralization of phenol was more complete when bare TiO2 was used as a photo-catalyst, whereas partial oxidation of phenol (i.e., into hydroquinone) was more dominant and total oxidation of phenol was supressed in the presence of surface-modified TiO2. Overall, one cannot simply say that hydrophilic modification of TiO2 leads to a higher affinity to H2O molecules with a higher yield of strongly-oxidizing agents (OH radicals) to increase the photo-catalytic activity in aqueous solutions. Our results imply that a subtle balance of the adsorption energy or rates of H2O, reactants, and reaction intermediates can be important factors for determining the photo-catalytic reaction rate. Different types of photo-catalyst surface modification can be beneficial or detrimental depending on the reaction. It is highlighted that one should be wary of evaluating the overall photo-catalytic activities of dissimilar catalysts based on the results of only a couple of reactions.
      Graphical abstract image

      PubDate: 2017-09-12T02:09:35Z
  • Effect of structural phase transformations under pressure on electronic
           and optical properties of CuInS2
    • Abstract: Publication date: November 2017
      Source:Current Applied Physics, Volume 17, Issue 11
      Author(s): Bo Gao, Hong-Tao Xue, Fu-Ling Tang, Yu-Wen Cheng
      First-principles plane-wave calculations were employed to study the phase transitions, electronic and optical properties of chalcopyrite CuInS2 (CIS) under pressure, which is a promising semiconductor compound material for nonlinear optical, photovoltaic and bio-applications. From the variations of Gibbs free energy and volume with pressure, we confirmed an experimentally found phase transformation of CIS from tetragonal I 4 ¯ 2d structure into the cubic Fm 3 ¯ m phase. It occurs at 7.9 GPa with a volume reduction of 15.6%, which are comparable with the experimental values of 9.5 GPa and 12%. A new possible phase transition of CIS from the cubic Fm 3 ¯ m structure to the orthorhombic Cmcm structure under higher pressure was predicted occurring at 49.6 GPa with a volume reduction about 0.64%. Using the more accurate HSE06 functional, we found that the growth rate of energy gap with pressure (dE g/dP) for the I 4 ¯ 2d phase is about 24.8 meV/GPa, very close to the experimental value of 24 meV/GPa. The calculated electronic properties for Fm 3 ¯ m and Cmcm phases show that CIS is a metallic material under high pressure, rather than a semiconductor. The optical absorption spectra indicate that with the increase of pressure the absorption edge of CIS becomes smaller while the optical energy gap is larger.
      Graphical abstract image

      PubDate: 2017-09-12T02:09:35Z
  • Effects of Fe insertion in CoFeB in the middle electrode on the properties
           of MgO double-barrier magnetic tunnel junctions
    • Abstract: Publication date: December 2017
      Source:Current Applied Physics, Volume 17, Issue 12
      Author(s): Jongill Hong, Sangho Lee
      We successfully improved the tunnel magnetoresistance ratio (TMR) of an MgO/CoFeB/MgO-based double-barrier magnetic tunnel junction (DMTJ) by inserting ultra-thin Fe into a CoFeB middle electrode. The Fe played as an absorber of B diffused out of the CoFeB and thereby facilitated the crystallization of the CoFeB at the interface. Changes in resistivity of the middle electrode with Fe insertion calculated by the modified current-in-plane tunneling method suggested that they can be explained by the formation of Fe borides, which is ascribed to the fact that Fe indeed promoted the diffusion of B by providing places for the B diffusion. As a result, Fe insertion improved the (001) texture of the middle electrode and thereby increased the TMR of the junction due to enhanced coherent tunneling. However, when inserted Fe was thick, the tunnel properties of DMTJs were degraded because of the absence of strong (001) texture of MgO. Materials and their thickness for a middle electrode are key parameters to successful application of DMTJs for spin devices.

      PubDate: 2017-09-07T02:09:22Z
  • Enhanced output power of InGaAs/GaAs infrared light-emitting diode with
           GaxIn1-xP tensile strain barrier
    • Abstract: Publication date: Available online 3 September 2017
      Source:Current Applied Physics
      Author(s): Hyung-Joo Lee, In-Kyu Jang, Won-Chan An, Lee Ku Kwac, Hong-Gun Kim, Joon Seop Kwak
      Various GaxIn1-xP strain barriers were evaluated for their ability to compensate for the strain of lattice mismatched InGaAs/GaAs MQWs structures. A GaxIn1-xP (χ = 0.53) tensile strain barrier, which was inserted between the n-confinement and InGaAs/GaAs multi-quantum well (MQW) active region, was effective in reducing the compressive strain caused by In0.07GaAs in multiple quantum wells (MQWs). Importantly, a remarkably enhanced PL intensity was obtained by retuning the strain of In0.07GaAs QWs based on a Ga0.53InP tensile strain barrier. A fabricated IR-LED chip, having retuned In0.08GaAs/GaAs MQWs with a Ga0.53InP tensile strain barrier, yielded double the light output power of the IR-LED chip without a Ga0.53InP strain barrier. This suggests that the use of a Ga0.53InP tensile strain barrier is essential for compensating for the compressive strain of lattice-mismatched InGaAs/GaAs MQWs with a 940 nm emitting wavelength, followed by the improved output power of the IR-LED chips.

      PubDate: 2017-09-07T02:09:22Z
  • Investigation of carbon monoxide adsorption onto sumanene (C21H12)
           decorated with Li+ ions toward its elimination
    • Abstract: Publication date: November 2017
      Source:Current Applied Physics, Volume 17, Issue 11
      Author(s): Adel Reisi-Vanani, Marziyeh Safipoor
      One of the important techniques to attract gaseous pollutant is placement of metals or their cations on carbon-based materials. In this study, Li+ ions were applied in order to promote adsorption of CO gas on sumanene bowl-shaped nanostructure. The results of theoretical calculations at MP2/6-311+G(d,p)//B3LYP/6-31G(d) level showed that the binding energy (BE) for chemisorption of Li+ ions on sumanene in convex faces is higher than concave one and decreases with the number of Li+ from one to three. It is observed that above Li+ ions or between them in bridge form at inner surface of Li+-sumanene configurations are the most appropriate sites for CO trapping. The CO-Li+-sumanene systems possessed the higher BE than CO-sumanene systems. Natural population analysis (NPA) and natural bond orbital (NBO) analysis obviously revealed that charge distribution in sumanene is affected by lithium ions and not by CO molecules. Besides, density of state (DOS) curves specified that the energy gap in Li+-sumanene reduced considerably after CO attraction. Consequently, decorated sumanene by Li+ ions is appropriate sorbent for removal CO contaminant from environment.

      PubDate: 2017-09-01T01:48:57Z
  • Pressure and molecular-weight dependences of elastic properties of
           polystyrene polymers studied by Brillouin spectroscopy
    • Abstract: Publication date: November 2017
      Source:Current Applied Physics, Volume 17, Issue 11
      Author(s): Byoung Wan Lee, Min-Seok Jeong, Jong Sun Choi, Jaehoon Park, Young Ho Ko, Kwang Joo Kim, Jae-Hyeon Ko
      Pressure and molecular-weight dependences of acoustic mode behaviors of polystyrene polymeric material were investigated by using Brillouin spectroscopy. The longitudinal, the transverse and the bulk sound velocities were measured over a wide pressure range from ambient pressure to more than 10 GPa for five polystyrene polymers whose molecular weight ranging from 3700 to 979200. The longitudinal and the bulk sound velocities displayed nearly the same pressure dependence for all polystyrenes indicating that the effective free volume is very similar in five polystyrene polymers despite the huge change in the molecular weight. The Poisson's ratio slightly increased with decreasing molecular weight.

      PubDate: 2017-09-01T01:48:57Z
  • Flexible transparent electrodes made of core-shell-structured carbon/metal
           hybrid nanofiber mesh films fabricated via electrospinning and
    • Abstract: Publication date: November 2017
      Source:Current Applied Physics, Volume 17, Issue 11
      Author(s): Jin Woo Huh, Hwan-Jin Jeon, Chi Won Ahn
      The development of practical flexible transparent electrodes is one of the major core technology fields for future nanoscale optoelectronics. Despite the many efforts to replace the indium tin oxide (ITO) electrode, preparing practical alternatives that satisfy the essential requirements of flexible transparent electrodes remains a challenge. In this work, core-shell-structured carbon/metal hybrid mesh (CS-CMHM) films, comprised of a metal layer coated onto conductive carbon nanofiber network structures, were fabricated using electrospinning and electroplating and demonstrated potential for use as flexible transparent electrodes. In contrast to previously described techniques that use conventional polymer fibers as sacrificial structures, the conductive carbon nanofibers used in the current technique that we developed provided bi-functionality: they formed conductive core channels and artificial supports of the metal structures. The CS-CMHM films displayed superior optoelectrical, mechanical, and thermal properties: they transmitted ∼91% of visible light, showed a low sheet resistance of ∼2.7 Ω/sq, and displayed excellent mechanical stability even after 10000 cycles of bending the films to a radius of 5 mm; also, applying a voltage of only 3 V to a transparent heater based on CS-CMHM films resulted in the temperature of the film surface increasing very rapidly in the first 20 s, and soon thereafter reaching ∼280 °C. Based on these results, we believe that the use of CS-CMHM films and the process we developed to fabricate them open up great opportunities for high-performance flexible transparent electronics.
      Graphical abstract image

      PubDate: 2017-09-01T01:48:57Z
  • Structural stability and electrical characteristic of DNA lattices doped
           with lanthanide ions
    • Abstract: Publication date: November 2017
      Source:Current Applied Physics, Volume 17, Issue 11
      Author(s): Sreekantha Reddy Dugasani, Bramaramba Gnapareddy, Jang Ah Kim, Sanghyun Yoo, Taehyun Hwang, Taesung Kim, Sung Ha Park
      The main aim of doping DNA lattices with lanthanide ions (Ln-DNA complex) is to change the physical functionalities for specific target applications such as electronics and biophotonics. Ln–DNA complexes based on a double-crossover DNA building block were fabricated on glass using a substrate-assisted growth method. We demonstrated the structural stability of Ln–DNA complexes as a function of Ln ion concentration by the atomic force microscopy. The Ln ion doping in DNA lattices was examined using a chemical reduction process, and the electrical characteristics of Ln–DNA complexes were tested using a semiconductor parameter analyzer. The structural phase transition of DNA lattices from the crystalline to amorphous phases occurred at a certain critical concentration of each Ln ion. Ln ions in DNA lattices are known to be intercalated between the base pairs and bound with phosphate backbones. When DNA lattices are properly doped with Ln ions, Ln–DNA complexes revealed the complete deformation with chemical reduction process by ascorbic acid. The current increased up to a critical Ln ion concentration and then decreased with further increasing Ln ions. Ln–DNA complexes will be useful in electronics and photonics because of their unique physical characteristics.

      PubDate: 2017-09-01T01:48:57Z
  • Surface chemistry modification in ITO films induced by Sn2+ ionic state
    • Abstract: Publication date: November 2017
      Source:Current Applied Physics, Volume 17, Issue 11
      Author(s): Jiwoong Kim, Dooyong Lee, Sehwan Song, Sam Yeon Cho, Jong-Seong Bae, Wanyeon Kim, BuHyun Youn, Yangdo Kim, Jeong-Soo Lee, Sang Don Bu, Sungkyun Park
      In this study, the surface-chemistry-dependent hydrophobicity and antibacterial properties of ITO films were examined. After annealing of the films, their surface root-mean-square roughness increased and remained the same regardless of the annealing environment. However, depending on the annealing environment (O2, N2, Ar, or vacuum), the contact angle increased with increasing Sn2+ contents in the films. Furthermore, the antibacterial effect of the annealed films decreased regardless of the annealing environment. The depth-dependent chemical state determined by X-ray photoelectron spectroscopy showed an increase in the Sn content at the surfaces of all films. In particular, the as-grown film exhibited the highest Sn content at the surface and also the strongest antibacterial effect.

      PubDate: 2017-09-01T01:48:57Z
  • Electrosynthesized poly(1,5-diaminonaphthalene)/polypyrrole nanowires
           bilayer as an immunosensor platform for breast cancer biomarker CA 15-3
    • Abstract: Publication date: November 2017
      Source:Current Applied Physics, Volume 17, Issue 11
      Author(s): Vân-Anh Nguyen, Huy L. Nguyen, Dzung T. Nguyen, Quan P. Do, Lam D. Tran
      In this paper, an electrosynthesized bilayer film of polypyrrole nanowire and poly(1,5diaminonaphthalene) on a disposable screen-printing carbon ink electrode is presented. The inner polypyrrole nanowire layer had a large surface-to-volume ratio and high conductivity in the neutral medium, whereas the outer layer of poly(1,5diaminonaphthalene) had functional amino groups on the polymer chains. The combination of polypyrrole nanowire and poly(1,5diaminonaphthalene) showed a promising material for electrochemical biosensing. Here we reported an electrochemical immunosensor based on this approach for the purpose of detecting breast cancer biomarkers. The bilayer could enhance the surface coverage of antibody anti-CA 15-3 and consequently improve the sensitivity and stability of the immunosensors. The magnetic beads were used as carriers of labeled antibody anti-CA15-3 and HRP (horseradish peroxidase) in order to achieve an amplification of the signal. Under optimized conditions, the linear range of the immunoassay was 0.05–20 U mL−1 with a detection limit of 0.02 U mL−1 CA 15-3 antigen.

      PubDate: 2017-09-01T01:48:57Z
  • Synthesis of pure and biocompatible gold nanoparticles using laser
           ablation method for SERS and photothermal applications
    • Abstract: Publication date: November 2017
      Source:Current Applied Physics, Volume 17, Issue 11
      Author(s): M. Vinod, Ramapurath S. Jayasree, K.G. Gopchandran
      In the recent past, gold nanoparticles synthesized using pulsed laser ablation in biocompatible mediums has attracted scientific and technological interest. In this work, it is found that the gold nanoparticles prepared using laser ablation of gold target in water is inherently non-toxic. These particles have shown that they are photothermally active when excited with 532 nm laser line, in conjunction with the plasmon band. The surface charge of these nanoparticles is found to be negative. The X-ray photoelectron spectroscopy measurements indicated the possibility of partial oxidation of the surfaces of these gold nanoparticles and electron micrographs indicated that the surfaces of these particles are relatively smooth. Raman measurements made with crystal violet as probe molecules using these nanoparticles as substrates and Raman spectra from L929 cells after incubation with these gold nanoparticles have shown that they can enhance the scattered Raman signal.
      Graphical abstract image

      PubDate: 2017-09-01T01:48:57Z
  • Influence of FeSe doping on superconducting properties of MgB2 by hybrid
           microwave method
    • Abstract: Publication date: November 2017
      Source:Current Applied Physics, Volume 17, Issue 11
      Author(s): Cheng Cheng, Zhenjie Feng, Qing Li, Xu Wang, Chuan Yu, Hao Chu, Ya Yang, Changqin Liu, Yiming Cao, Zhe Li, Jingzhe Chen, Chao Jing, Shixun Cao, Jincang Zhang
      The effect of FeSe doping on the physical properties of MgB2 is studied. Bulk samples of the FeSe doped MgB2 with weight ratio x ( F e S e : M g B 2 ) = 0 % , 3 % , 7 % a n d 10 % were prepared by hybrid microwave method. It is proved that FeSe is not stable together with MgB2. Fe2+ enters into MgB2 lattice, some Mg2+ and Se2− are combined into the new impurity compound MgSe. The superconducting transition temperature (T c ) slightly decreased with increasing doping content of FeSe from R-T and M-T curves, which results from the substitution of Mg2+ by Fe2+ in the MgB2 lattice. The J c increase slightly with the FeSe doping content increasing from 3 wt % to 10 wt %, which results from the increasing MgSe impurity pinning centers.

      PubDate: 2017-09-01T01:48:57Z
  • Investigation on I-V characteristics of current induced metal insulator
           transition in VO2 device
    • Abstract: Publication date: November 2017
      Source:Current Applied Physics, Volume 17, Issue 11
      Author(s): Gi Yong Lee, Howon Kim, Bongjin Simon Mun, Changwoo Park, Honglyoul Ju
      The I-V characteristics of two terminal planar VO2 film devices are investigated as the devices undergo the current induced metal insulator transition (I-MIT). The I-MIT occured when the device resistivity reached ∼7  Ωcm , where metallic grains formed initial conductive current path within insulating matrix. The transition time needed for the I-MIT increased with increasing external resistance, REXT, connected to the device in series, i.e. ∼390 μs (REXT = 5 kΩ) to ∼1400 μs (REXT = 20 kΩ). The transition time is closely related to the RC time delay from capacitance discharge of the VO2 device. During the I-MIT, the amount of discharge current was estimated as large as ∼100 mA, which was larger than the current just before the I-MIT. After the I-MIT, the current density decreased from 1.1 × 106 A/cm2 to 6.5 × 105 A/cm2, suggesting a large temperature changes up to ∼300 °C.

      PubDate: 2017-09-01T01:48:57Z
  • Degradation of fill factor in P3HT:PCBM based organic solar cells
    • Abstract: Publication date: November 2017
      Source:Current Applied Physics, Volume 17, Issue 11
      Author(s): Vinamrita Singh
      In this paper, the degradation of fill factor with time of organic bulk heterojunction solar cells has been investigated up to 312 h. The experimental data of P3HT:PCBM solar cells has been analyzed theoretically to determine the parameters which affect the FF. The existing empirical formula has been applied to degradation data, and it was found to deviate drastically as the cell degrades, indicating that the correct behavior of solar cell is not imitated using the current FF formula. In view of the discrepancy, the expression for fill factor has been modified taking into account the material and device properties, which directly influence the working of a solar cell. All the values can be determined experimentally. The results of the modified expression gives better theoretical fit of FF with time. The results highlight the parameters which should be targeted in order to overcome the short lifetime of organic solar cells.

      PubDate: 2017-09-01T01:48:57Z
  • Observation of spin dependent electrochemical potentials at room
           temperature in a quantum well structure
    • Abstract: Publication date: November 2017
      Source:Current Applied Physics, Volume 17, Issue 11
      Author(s): Youn Ho Park, Hyun-jun Kim, Joonyeon Chang, Hyun Cheol Koo
      Spin transport with a strong Rashba spin splitting is observed in a semiconductor channel. Using the current injection into the side of the quantum well, the potentiometric signal and the spin-torque-induced magnetization change are simultaneously detected. In this geometry, the spin current is directly injected from the ferromagnetic electrode into the quantum well channel and the electrochemical potential is monitored by the detection ferromagnet. For the side injection instead of vertical injection, the milling of the top cladding layer is not necessary, so the efficient spin transport and the undamaged Rashba spin splitting can be realized. The ferromagnetic detector senses the Rashba-effect-induced electrochemical potential shift brought by the charge current and this potentiometric signal is also modified by the magnetization rotation induced by the spin current. The large potential changes of 1.03 Ω and 0.96 Ω are observed at 1.8 K and 300 K, respectively.

      PubDate: 2017-09-01T01:48:57Z
  • Comparative study for electrical transport characteristics of
           self-assembled monolayers formed by benzenethiol, cyclohexanethiol, and
    • Abstract: Publication date: November 2017
      Source:Current Applied Physics, Volume 17, Issue 11
      Author(s): Junwoo Kim, Hyunhak Jeong, Sicheon Seong, Mingi Kim, Dongku Kim, Wang-Taek Hwang, Yeonsik Jang, Barbara Yuri Choi, Jeongmin Koo, Seung Bum Park, Jaegeun Noh, Takhee Lee
      We investigated the effect of molecular backbone structure on the electrical transport properties of self-assembled monolayer (SAM)-based molecular devices which were made with using three different molecules; benzenethiol (denoted as BT), cyclohexanethiol (CHT), and adamantanethiol (ADT). These molecules have similar ring-shaped backbone structures but different molecular orbital systems. The molecular devices were fabricated as a vertical metal-SAM-molecule structure by a conventional optical lithography-based microscale via-hole technique with employing PEDOT:PSS (poly(3,4-ethylenedioxythiophene)) stabilized with poly(4-styrenesulfonic acid) interlayer, which leads to a high device yield. We found that the current density of BT molecular devices was one order higher than that of CHT and ADT molecular devices due to the different molecular orbital systems. Also, we observed that the current densities of CHT and ADT devices were slightly different according to the statistical analysis because of the different structural uniformity of SAMs.

      PubDate: 2017-09-01T01:48:57Z
  • Tunnel magnetoresistance of homocatenated silicon and germanium clusters
    • Abstract: Publication date: November 2017
      Source:Current Applied Physics, Volume 17, Issue 11
      Author(s): Yukihito Matsuura
      The spin-polarized transport characteristics of homocatenated clusters of group 14 elements have been studied using the non-equilibrium Green's function formalism. Compared with the carbon cluster, silicon and germanium clusters with extended σ-conjugation had a high tunnel magnetoresistance (TMR) ratio at a low bias voltage. This phenomenon was caused by the low energy level of the LUMO from σ-conjugation extended throughout the whole molecule and by the spin polarization of the sulfur located between the σ-conjugated system and the ferromagnetic electrode.
      Graphical abstract image

      PubDate: 2017-09-01T01:48:57Z
  • Rectifying electronic transport and the role of Fowler-Nordheim tunneling
           in Ag/PVDF/Au capacitor structures
    • Abstract: Publication date: November 2017
      Source:Current Applied Physics, Volume 17, Issue 11
      Author(s): K. Pramod, R.B. Gangineni
      The electron transport through β phase dominant Polyvinylidene fluoride (PVDF) thin films in its intrinsic form is investigated and reports the stable rectification up to ±30 V in Ag/PVDF/Au capacitor structures. A practical resistance ratio of ∼40 between −1 V and 1 V and a maximum ratio of ∼77 at −24 V and 24 V exhibits its potential usage in selector devices. Furthermore, the nonpolar electronic transport is analysed with Schottky, Space Charge Limited Current (SCLC), Poole-Frenkel (PF) and Fowler-Nordheim (FN) tunneling mechanisms with respect to electrode, thickness and temperature variations.

      PubDate: 2017-09-01T01:48:57Z
  • Surface engineering of the electron collecting layers for high performance
           organic photovoltaic cells
    • Abstract: Publication date: November 2017
      Source:Current Applied Physics, Volume 17, Issue 11
      Author(s): Ju Won Lim, Jae Won Shim, Kyungwha Chung, Dong Ha Kim, Won Kook Choi, Do Kyung Hwang
      Surface engineering of the electron collecting layers (ECLs) is a straightforward and practical strategy to develop high performance inverted structure organic solar cells (OSCs). Here, we systematically investigate four different types of surface modified ECLs to implement high performance low-energy band gap poly[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-bA]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]-thiophenediyl] (PTB7) and [6,6]-phenyl-C70-butyric acid methyl ester (PC70BM) based inverted OSCs: (1) single PEIE, (2) ZnO:PEIE mixture (1:1 vol ratio), (3) PEIE/ZnO bilayer, and (4) ZnO/PEIE bilayer. OSCs with the ZnO/PEIE ECL show the highest power conversion efficiency (PCE) value of 8.61% while all the other devices exhibit PCE values of less than 7.80%. The excellent surface coverage as well as proper band alignment of the ZnO/PEIE bilayer leads to the highest device performance.
      Graphical abstract image

      PubDate: 2017-09-01T01:48:57Z
  • A novel orange-red emitting Ba2Ca(BO3)2:Sm3+ phosphor to fill the amber
           gap in LEDs: Synthesis, structural and luminescence characterizations
    • Abstract: Publication date: November 2017
      Source:Current Applied Physics, Volume 17, Issue 11
      Author(s): M. Manhas, Vinay Kumar, Vivek K. Singh, J. Sharma, Ram Prakash, Vishal Sharma, A.K. Bedyal, H.C. Swart
      The present paper reports on the structural and luminescent properties of un-doped and Sm3+ doped Ba2Ca(BO3)2 phosphors synthesized by the conventional solid state method. For structural characterizations, the X-ray diffraction, FTIR spectroscopy and Rietveld refinement method were used. The FTIR spectrum was composed of basic BO3 and BO4 structural units of borates. The Sm3+ doped phosphors under 402 nm (6H5/2 → 4L13/2) excitation, showed an orange red emission corresponding to the 601 nm (4G5/2 → 6H7/2) transition of the Sm3+ ion. An increase in the PL emission intensity was observed up to 2 mol % with the increase in Sm3+ ions concentration. The critical distance between the Sm3+– Sm3+ ions were found to be 24.36 Å. Moreover, the phosphors decaytime and optical bandgap at different concentration of Sm3+ ion also have been discussed in details. All the results show that Ba2Ca(BO3)2:Sm3+ phosphor may be used with a near ultraviolet (n-UV) chip to fill the amber gap in light emitting diodes (LEDs).
      Graphical abstract image

      PubDate: 2017-07-28T02:01:53Z
  • Structure, electronic properties and electronic excitation analyses of
           Si60Si60 dimer and Si59AlSi59P complex
    • Abstract: Publication date: November 2017
      Source:Current Applied Physics, Volume 17, Issue 11
      Author(s): Ambrish Kumar Srivastava, Sarvesh Kumar Pandey, Neeraj Misra
      The electronic properties of nanoclusters, such as Si60 cage, are remarkably changed by substitution of heteroatom such as Al or P. How do such impure Si60 cages behave when brought together to form a complex? To address this, we have performed DFT and TD-DFT based calculations on Si60 Si60 dimer and Si59AlSi59P complex. We have explored various electronic properties of Si59AlSi59P complex and compared with those of Si60 Si60 dimer. We notice that the bonding along with binding energies of cages in the complex is slightly different than that of dimer. The higher dipole moment and smaller energy gap of the complex compared to dimer suggest its increased polarity and conductivity. The density-of-state curves reveal that the frontier orbitals of the complex are slightly shifted relative to dimer such that their energy gap is decreased. The electronic excitation analyses suggest that the electronic transition in Si59AlSi59P complex takes place via charge transfer (CT) mode, and the strength of this CT interaction is much larger than that of Si60 Si60 dimer. This is confirmed by larger oscillator strength, larger distance between the centroid of hole and electron as well as larger Δr index value. We believe that these findings might be useful in the application of Si-nanoclusters in the field of molecular electronics and nanoelectronics.
      Graphical abstract image

      PubDate: 2017-07-28T02:01:53Z
  • Enhancing the electrical conductivity and thermoelectric figure of merit
           of the p-type delafossite CuAlO2 by Ag2O addition
    • Abstract: Publication date: October 2017
      Source:Current Applied Physics, Volume 17, Issue 10
      Author(s): Sarayut Pantian, Rachsak Sakdanuphab, Aparporn Sakulkalavek
      (CuAlO2)1-x(Ag2O)x specimens with 0 ≤ x ≤ 0.06 were prepared through the sintering of mixtures of CuO, Al2O3 and Ag2O powders at 1373 K. Hall effect, Seebeck coefficient and electrical conductivity measurements were subsequently employed to assess the electrical transport properties. The electrical conductivity of the as-sintered samples was found to increase with Ag2O addition as a result of increases in the carrier density. Over the temperature range of 323–623 K, the transport properties can be attributed to thermally activated transitions from the acceptor state to the valence band. In contrast, the variable range hopping theory is applicable over the temperature range of 623–873 K. Ag2O addition evidently reduces the defect binding energy in the electronic structure of the CuAlO2. The addition of this compound also obstructs the formation of both a spinel phase and CuO, such that the oxygen off-stoichiometry value and the carrier density are increased with increasing Ag2O levels. The presence of Ag metal has the main effect on thermal conductivity below 400 K, while above 400 K increases in the phonon concentration affect the conductivity. The highest value obtained for the figure of merit was 0.0044 at 573 K, from a sample containing 0.2 at.% Ag2O.
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      PubDate: 2017-07-08T01:21:26Z
  • Theoretical investigation of electronic, magnetic, transport and optical
           properties of the pure and doped cuprate superconductor HgBa2CuO4+δ
    • Abstract: Publication date: October 2017
      Source:Current Applied Physics, Volume 17, Issue 10
      Author(s): Khalid Quertite, Halima Zaari, Hamid Ez-Zahraouy, Abdallah El Kenz, Hamid Oughadou, Abdelilah Benyoussef
      We report detailed DFT calculations and Monte Carlo simulations on the pure and doped cuprate superconductor HgBa2CuO4+δ. For the pure compound (δ = 0), we have obtained an insulating behavior with strong antiferromagnetic copper spin correlations in the CuO2 plane. The high value of the calculated Néel temperature T N  = 333 K reflects the large in-plane exchange interaction J = -145 meV. The obtained optical properties and critical exponents demonstrate the anisotropic quasi-2D character of this type of materials. As for the doped compound the electronic structure and the transport properties have been investigated for various values of doping. Based on these data, we suggest a prediction of the value of optimum doping for HgBa2CuO4+δ (δoptimal = 0.125).

      PubDate: 2017-07-08T01:21:26Z
  • Investigation on native defects of α-MgAgSb and its effects on
           thermoelectric properties using first principles calculations
    • Abstract: Publication date: October 2017
      Source:Current Applied Physics, Volume 17, Issue 10
      Author(s): Zhuoyi Pang, Xiwen Zhang, Chao Wang
      α-MgAgSb is a promising thermoelectric materials having good performance at medium temperature. Native defects in α-MgAgSb are frequently reported experimentally and are tightly involved in the thermoelectric properties of α-MgAgSb. In this paper, all possible native defects in α-MgAgSb are calculated as well as detailed results are given and discussed. The concentrations of several dominant native defects, for example, V Ag and Ag Sb , could reach up to 10−4 cm−3 at 540 K. Furthermore, the electronic structure and transport properties of α-MgAgSb with dominant native defects are investigated. Results show that the introduction of Ag Mg and V Ag contributes to a much lower inertial mass and slight decrease in Seebeck coefficient. The lattice thermal conductivity is greatly reduced with the introduction of native defects. For α-MgAgSb with V Ag , the peak ZT could reach up to 1.84 at 420 K. Our calculation demonstrates that defect engineering is an effective strategy to enhance thermoelectric performance of the materials.

      PubDate: 2017-07-08T01:21:26Z
  • Application of electromagnetic processing for development of
           high-performance sintered powder metal parts
    • Abstract: Publication date: October 2017
      Source:Current Applied Physics, Volume 17, Issue 10
      Author(s): Daudi R. Waryoba, Winston Roberts
      Electromagnetic processing was used to study the effects of electro-magneto forming on the dimensional control and thermal stability of sintered powder metal (PM) parts. The investigation was carried out on sinter-hardened, low chromium-molybdenum bainitic steel. The results show an increase in the microhardness of about 14% for the electromagnetic processed parts compared to the as-sintered parts. This was attributed to the 2% increase in the density, 17% and 29% reduction in the volume fraction of porosity and width of the bainitic lath, respectively, due to the electromagnetic processing. Dimensional characterization was carried out using a vertically aligned push-rod dilatometer. After four thermal cycles of heating and cooling, at a controlled rate of 5 °C/min to 1000 °C, the electromagnetic processed parts exhibited reduced dimensional change of about 44% lower than for the as-sintered parts. This is significantly important for applications that demand high dimensional tolerance and performance, especially at elevated temperatures.

      PubDate: 2017-07-08T01:21:26Z
  • Modeling and simulation of efficiency droop in GaN-based blue
           light-emitting diodes incorporating the effect of reduced active volume of
           InGaN quantum wells
    • Abstract: Publication date: October 2017
      Source:Current Applied Physics, Volume 17, Issue 10
      Author(s): Han-Youl Ryu, Guen-Hwan Ryu, Young-Hwan Choi, Byungjin Ma
      The efficiency droop of InGaN-based blue light-emitting diodes (LEDs) is analyzed using numerical simulations with a modified ABC carrier recombination model. The ABC model is modified to include the effect of reduced effective active volume of InGaN quantum wells (QWs) and incorporated into the numerical simulation program. It is found that the droop of internal quantum efficiency (IQE) can be well explained by the effect of reduced light-emitting active volume without assuming a large Auger recombination coefficient. A simulated IQE curve with the modified ABC model is found to fit quite well with a measured efficiency curve of an InGaN LED sample when the effective active volume takes only 2.5% of the physical volume of QWs. The proposed numerical simulation model incorporating the reduced effective active volume can be advantageous for use in the modeling and simulation of InGaN LEDs for higher efficiency.

      PubDate: 2017-07-08T01:21:26Z
  • Effect of annealing treatment on the uniformity of CeO2/TiO2 bilayer
           resistive switching memory devices
    • Abstract: Publication date: October 2017
      Source:Current Applied Physics, Volume 17, Issue 10
      Author(s): M. Ismail, A.M. Rana, S.-U. Nisa, F. Hussain, M. Imran, K. Mahmood, I. Talib, E. Ahmed, D.H. Bao
      Bilayer CeO2/TiO2 films with high-k dielectric property were prepared by rf magnetron sputtering technique at room temperature. Effect of annealing treatment on resistive switching (RS) properties of bilayer CeO2/TiO2 films in O2 ambient at different temperature in the range of 350–550 °C was investigated. Our results revealed that the bilayer films had good interfacial property at 500 °C and this annealing temperature is optimum for different RS characteristics. Results showed that bilayer CeO2/TiO2 film perform better uniformity and reliability in resistive switching at intermediate temperature (i.e. 450 °C and 500 °C) instead of low and high annealing temperature (i.e. 350 °C and 550 °C) at which it exhibits poor crystalline structure with more amorphous background. Less Gibbs free energy of TiO2 as compared to CeO2 results in an easier re-oxidation of the filament through the oxygen exchange with TaN electrode. However, the excellent endurance property (>2500 cycles), data retentions (105 s) and good cycle-to-cycle uniformity is observed only in 500 °C annealed devices. The plots of cumulative probability, essential memory parameter, show a good distribution of Set/Reset voltage.

      PubDate: 2017-07-08T01:21:26Z
  • Topological confinement effect of edge potentials in zigzag-edge graphene
           nanoribbons under a staggered bulk potential
    • Abstract: Publication date: October 2017
      Source:Current Applied Physics, Volume 17, Issue 10
      Author(s): Kyu Won Lee, Cheol Eui Lee
      We have investigated topological confinement effects of edge potentials on gapless edge states in zigzag-edge graphene nanoribbons (ZGNRs) under a staggered bulk potential. A variety of gapless edge states were predicted with the concept of topological confinement effect alone, which was confirmed by using tight-binding model calculations. Half-metallicity of ZGNR, which has been semiclassically described, was revealed to fundamentally result from a topological confinement effect. Edge potentials were found to allow an infinitesimal staggered bulk potential to result in gapless edge states, regardless of the ribbon width. A uniform or staggered potential applied to the boundary region narrower than a critical width was found to play a role of the edge potentials, and the critical width was estimated.

      PubDate: 2017-06-27T06:59:00Z
  • Enhancing magnetoelectric properties of 0–3 particulate composite
           ceramics by introducing nano-sized sintering aids via self-combustion
    • Abstract: Publication date: October 2017
      Source:Current Applied Physics, Volume 17, Issue 10
      Author(s): Xiangyong Zhao, Dun Wu, Bijun Fang, Feifei Wang, Yanxue Tang, Wangzhou Shi, Jianning Ding
      The 0.55Pb(Ni1/3Nb2/3)O3-0.05PbHfO3-0.4PbTiO3/Ni0.875Zn0.125Fe2O4 (PNNHT/NZF) 0–3 particulate composite ceramics were prepared by the conventional solid-state reaction method via introducing the nano-sized WO3 and CuO sintering aids by the self-combustion method. Due to the introducing of nano-sized sintering aids, densified PNNHT/NZF composite ceramics are synthesized sintered at low sintering temperature. Furthermore, the nano-sized sintering aids act effectively as blocking layers, leading to compact composite ceramics with homogenously dispersed and isolated microstructure morphology, inhibiting inter-phase diffusion, avoiding interfacial chemical reaction, and achieving strong inter-phase coupling. Therefore, the synthesized PNNHT/NZF composite ceramics exhibit enhanced magnetoelectric properties.

      PubDate: 2017-06-27T06:59:00Z
  • Metastable argon atoms under significant neutral depletion in helicon
           plasmas by laser-induced fluorescence
    • Abstract: Publication date: October 2017
      Source:Current Applied Physics, Volume 17, Issue 10
      Author(s): B.H. Seo, J.H. Kim, S.J. You
      We study the spatial distribution of the metastable-state argon atoms in high density helicon plasmas by means of laser-induced fluorescence. It is observed that the neutral argon in metastable-state has an anomalous radial distribution in density; it has a caldera-like shape radially, which is rare in typical low-temperature plasmas such as inductively coupled plasmas wherein the density increases toward the discharge center, as previously reported. The formation of the distribution can be explained as it forms by the combined effects of significant neutral depletion in high plasma density, off-axis electron-density distribution, and increasing diffusive loss toward the wall. To establish the assertion with the underlying physics, we calculate a simple global model and obtain the neutral density distribution in metastable-state under various conditions. The calculated results qualitatively agree with the experimental results.

      PubDate: 2017-06-27T06:59:00Z
  • Triple-band metamaterial absorber based on single resonator
    • Abstract: Publication date: October 2017
      Source:Current Applied Physics, Volume 17, Issue 10
      Author(s): Young Ju Kim, Ji Sub Hwang, Young Joon Yoo, Bui Xuan Khuyen, Xianfeng Chen, YoungPak Lee
      The single resonator generally reveals a single absorption band, and the resonators with different sizes or shapes have to be arranged in order to achieve multi-absorption bands. We propose the triple-band metamaterial absorber by utilizing only single resonator. Meta-atoms are made of the toothed-wheel shape metallic pattern and a continuous metallic plane, separated by a dielectric layer. The first and the third absorption bands are induced by the fundamental and the third-harmonic magnetic resonances, respectively, and the second absorption band is induced by the magnetic resonance relevant to two grooves. In addition, the diffraction peak appears between the second and the third absorption bands, due to the surface currents which are separated between the upper and the lower metallic pattern parts. The proposed structure is scalable to smaller size for the infrared and the visible regimes.

      PubDate: 2017-06-27T06:59:00Z
  • Comparison of theoretical and experimental results for band-gap-graded
           CZTSSe solar cell
    • Abstract: Publication date: Available online 13 June 2017
      Source:Current Applied Physics
      Author(s): Mehran Minbashi, Mir Kazem Omrani, Nafiseh Memarian, Dae-Hwan Kim
      The simulation of CZTSSe solar cells is presented in this paper. The simulation results are in reasonable agreement with the experimental data, indicating the reliability of simulation results. New structure is proposed to increase the functionality of the cell. Improved functional performances are achieved by inserting a P-Silicon (P-Si) layer as back surface field. Simulation results suggest that by inserting this P-Si layer, efficiency of the CZTSSe solar cell increases from 12.6% to 16.59%, which is a significant improvement. For the champion cell JSC = 36.27 mA/cm2, VOC = 0.625 V and FF = 73.11% has been achieved.

      PubDate: 2017-06-15T06:51:29Z
  • Enhanced efficiency and stability of polymer solar cells using
           solution-processed nickel oxide as hole transport material
    • Abstract: Publication date: Available online 12 June 2017
      Source:Current Applied Physics
      Author(s): Shanmugam Parthiban, Seungmin Kim, Vellaiappillai Tamilavan, Jihoon Lee, Insoo Shin, D. Yuvaraj, Yun Kyung Jung, Myung Ho Hyun, Jung Hyun Jeong, Sung Heum Park
      Solution-processed nickel oxide (s-NiOx) was synthesized for use as hole-transport layers (HTLs) in the fabrication of polymer solar cell (PSC) devices. The s-NiOx thin-films were deposited using spin-coating and post-annealed at 300 °C, 400 °C, or 500 °C. With increased annealing temperature, the nickel acetate precursor decomposes more fully and forms s-NiOx films that show larger crystalline grain sizes with lower root mean square surface roughness. Bulk heterojunction solar cells fabricated with the new random polymer RP(BDT-PDBT) and [6,6]-phenyl-C70-butyric acid methyl ester (PC70BM) using s-NiOx as HTLs exhibit a 4.46% enhancement in power conversion efficiency and better stability compared to conventional PSCs using poly (3,4-ethylenedioxythiophene):poly(styrene sulfonate) as HTLs. We believe that the solution-processable and highly stable s-NiOx could be a potential alternative for functional interface materials in optoelectronic devices.

      PubDate: 2017-06-15T06:51:29Z
  • A study of energy transfer phenomenon leading to photon up-conversion in
    • Abstract: Publication date: Available online 8 June 2017
      Source:Current Applied Physics
      Author(s): Nikifor Rakov, Glauco S. Maciel
      When Ho3+:Yb3+:CaF2 crystalline powders prepared by combustion synthesis were exposed to near-infrared (λ ∼ 975 nm) radiation, intense photon up-conversion (UC) was observed at the visible with emission bands peaked at ∼ 545, ∼650 and ∼750 nm identified as 4f-4f transitions from higher levels (5F4, 5S2) and 5F5 to lower levels 5I8 and 5I7 of Ho3+. The emission bands at the green and red, in particular, have been demonstrated to be useful for temperature sensing based on luminescence intensity ratio technique. However, no model is available in literature to explain the change of the electronic populations of states (5F4, 5S2) and 5F5 with temperature. The UC phenomenon was studied from both theoretical and experimental points of view. A rate equation model with temperature dependent parameters for Ho3+ and Yb3+ electronic populations considering a high sensitization of Ho3+ ions by Yb3+ ions was used. High Yb3+ → Ho3+ energy transfer efficiency was found (∼88% at room temperature). The change with temperature predicted by the model for the luminescence intensity ratio of the UC green and red emission lines agrees well with the experimental data.
      Graphical abstract image

      PubDate: 2017-06-10T06:47:32Z
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