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ENGINEERING (1213 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: 7)
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: 255)
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: 9)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 7)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 18)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 6)
Advances in Complex Systems     Hybrid Journal   (Followers: 7)
Advances in Engineering Software     Hybrid Journal   (Followers: 27)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 16)
Advances in Fuzzy Systems     Open Access   (Followers: 5)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 11)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 22)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 27)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 10)
Advances in Natural Sciences: Nanoscience and Nanotechnology     Open Access   (Followers: 30)
Advances in Operations Research     Open Access   (Followers: 12)
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: 5)
Advances in Remote Sensing     Open Access   (Followers: 40)
Advances in Science and Research (ASR)     Open Access   (Followers: 6)
Aerobiologia     Hybrid Journal   (Followers: 2)
African Journal of Science, Technology, Innovation and Development     Hybrid Journal   (Followers: 6)
AIChE Journal     Hybrid Journal   (Followers: 32)
Ain Shams Engineering Journal     Open Access   (Followers: 5)
Akademik Platform Mühendislik ve Fen Bilimleri Dergisi     Open Access   (Followers: 1)
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: 17)
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: 8)
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: 18)
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   (Followers: 1)
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: 5)
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: 8)
Arkiv för Matematik     Hybrid Journal   (Followers: 1)
ASEE Prism     Full-text available via subscription   (Followers: 3)
Asia-Pacific Journal of Science and Technology     Open Access  
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: 9)
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: 6)
Bautechnik     Hybrid Journal   (Followers: 1)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 24)
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: 4)
Bharatiya Vaigyanik evam Audyogik Anusandhan Patrika (BVAAP)     Open Access   (Followers: 1)
Biofuels Engineering     Open Access   (Followers: 1)
Biointerphases     Open Access   (Followers: 1)
Biomaterials Science     Full-text available via subscription   (Followers: 10)
Biomedical Engineering     Hybrid Journal   (Followers: 15)
Biomedical Engineering and Computational Biology     Open Access   (Followers: 14)
Biomedical Engineering Letters     Hybrid Journal   (Followers: 5)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 18)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 34)
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   (Followers: 1)
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: 14)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Cahiers, Droit, Sciences et Technologies     Open Access  
Calphad     Hybrid Journal  
Canadian Geotechnical Journal     Hybrid Journal   (Followers: 30)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 44)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 8)
Case Studies in Thermal Engineering     Open Access   (Followers: 4)
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: 8)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysis Today     Hybrid Journal   (Followers: 7)
CEAS Space Journal     Hybrid Journal   (Followers: 2)
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: 24)
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: 4)
Cogent Engineering     Open Access   (Followers: 2)
Cognitive Computation     Hybrid Journal   (Followers: 4)
Color Research & Application     Hybrid Journal   (Followers: 2)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 14)
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: 27)
Composite Interfaces     Hybrid Journal   (Followers: 6)
Composite Structures     Hybrid Journal   (Followers: 271)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 199)
Composites Part B : Engineering     Hybrid Journal   (Followers: 256)
Composites Science and Technology     Hybrid Journal   (Followers: 193)
Comptes Rendus Mécanique     Full-text available via subscription   (Followers: 2)
Computation     Open Access  
Computational Geosciences     Hybrid Journal   (Followers: 15)
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: 8)
Computer Science and Engineering     Open Access   (Followers: 19)
Computers & Geosciences     Hybrid Journal   (Followers: 30)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 7)
Computers and Electronics in Agriculture     Hybrid Journal   (Followers: 5)
Computers and Geotechnics     Hybrid Journal   (Followers: 11)
Computing and Visualization in Science     Hybrid Journal   (Followers: 6)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 33)
Conciencia Tecnologica     Open Access  
Concurrent Engineering     Hybrid Journal   (Followers: 3)
Continuum Mechanics and Thermodynamics     Hybrid Journal   (Followers: 8)
Control and Dynamic Systems     Full-text available via subscription   (Followers: 9)
Control Engineering Practice     Hybrid Journal   (Followers: 43)
Control Theory and Informatics     Open Access   (Followers: 8)
Corrosion Science     Hybrid Journal   (Followers: 25)
Corrosion Series     Full-text available via subscription   (Followers: 6)
CT&F Ciencia, Tecnologia y Futuro     Open Access   (Followers: 1)

        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  [3123 journals]
  • OPE molecular junction as a hydrogen gas sensor
    • Abstract: Publication date: March 2018
      Source:Current Applied Physics, Volume 18, Issue 3
      Author(s): Jian-Guo Xin, Chuan-Lu Yang, Mei-Shan Wang, Xiao-Guang Ma
      Oligo(phenylene ethynylene) (OPE) molecular junction has been suggested as a H2 molecule sensor based on calculations using the first principles of density–functional theory and non-equilibrium Green's function. The electronic transport properties of the OPE molecule between two Au electrodes with or without adsorbed H2 molecules are investigated. Results show that the adsorbed H2 molecule significantly changes the characteristics of the current–voltage curve of the OPE molecular junction. The pure OPE molecular junction exhibits a significant negative differential resistance, but this kind of phenomenon will disappear or weaken after hydrogen molecules are adsorbed. The conductance of the junction also obviously decreases in the bias range of [−0.4, 0.4] V after adsorbing H2 molecules. These effects can be used to design a H2 molecule sensor.
      Graphical abstract image

      PubDate: 2018-01-10T07:07:39Z
  • First principles studies on the elastic, thermodynamic properties and
           electronic structure of Ti15−xMoxSn compounds
    • Abstract: Publication date: March 2018
      Source:Current Applied Physics, Volume 18, Issue 3
      Author(s): Chunmei Chen, Wei He, Lijing Ding, Xiaohui Song, Jinhui Huang, Tao Wang, Guoren Huang
      The structural, elastic, thermodynamic and electronic properties of the Ti15−xMoxSn compounds were systematically investigated by means of first-principles calculations based on the density functional theory (DFT). The calculated results demonstrate the Ti15−xMoxSn compounds still remain the stable β phase structure. The calculation of cohesive energy shows that the structural stability of the Ti15−xMoxSn compounds increases apparently with the increase of Mo content. According to Hooke's law, the single crystal elastic constants were obtained and show that all the calculated compounds keep mechanical stability. Then the bulk modulus B, shear modulus G, Young's modulus E and Poisson's ratio ν of polycrystalline aggregates were calculated at zero pressure. The calculated results show that among these Ti15−xMoxSn compounds, Ti4Mo11Sn exhibits the largest stiffness while Ti12Mo3Sn shows the greatest ductility. The compounds Ti12Mo3Sn and Ti11Mo4Sn with the two lowest elastic Young's modulus of 61.01 GPa and 65.59 GPa are expected to be promising metallic biomaterials for implant applications. Besides, the Debye temperature Θ D and the electronic density of states (DOS) are also investigated and discussed.

      PubDate: 2018-01-10T07:07:39Z
  • Colloidal stability measurements of graphene nanoplatelets covalently
           functionalized with tetrahydrofurfuryl polyethylene glycol in different
           organic solvents
    • Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): Siti Shafiah Shazali, Ahmad Amiri, Mohd Nashrul Mohd Zubir, Shaifulazuar Rozali, Mohd Zakuan Zabri, Mohd Faizul Mohd Sabri
      In this study, a facile, efficient, and cost-effective method was proposed for mass-production of tetrahydrofurfuryl polyethylene glycol-functionalized graphene nanoplatelets (TFPEG-treated GNPs) with improved colloidal stability in water and different organic solvents. In this method, zirconium(IV) oxychloride octahydrate was used as catalyst to covalently functionalize GNPs with TFPEG via direct esterification of carboxylic acid on the GNPs with the hydroxyl chains of TFPEG. Covalent functionalization was verified by Fourier transform infrared spectroscopy, Raman spectroscopy, and thermogravimetric analysis. Further, the morphology of the TFPEG-treated GNPs was determined via a high-resolution transmission electron microscopy. The stability of the treated GNPs in colloidal form was examined by dispersing 0.01 wt% of the solid sample into different organic solvents namely distilled water, methanol, ethanol, ethylene glycol, and 1-hexanol. It was found that the sedimentation rate of TFPEG-treated GNPs in distilled water, methanol, ethanol, ethylene glycol, and 1-hexanol was at 11, 25, 36, 18, and 47%, respectively, recorded after 15 days. Viscosity and thermal conductivity of water-based TFPEG-treated GNP nanofluids were also measured at different concentrations (0.100, 0.075, 0.050, and 0.025 wt%). The results suggest that these nanofluids have great potential for use as working fluids in industrial heat transfer systems.
      Graphical abstract image

      PubDate: 2018-01-10T07:07:39Z
  • Electric field involved transport at elevated temperature in
           nanocrystalline silicon carbide nitride (nc-SiCN) thin films for harsh
           environment applications
    • Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): Narendra Singh, Kirandeep Singh, Davinder Kaur
      The present study represents a systematic temperature dependent charge transport and dielectric properties of nanocrystalline silicon carbide nitride (nc-SiCN) thin films grown on Pt/Ti/SiO2/Si substrate. A large negative temperature coefficient of resistance (TCR) ranging from 6200 to 2300 ppmK-1 in the temperature range 300–773 K, suggests that the nc-SiCN thin films could be useful for futuristic thermal-based sensors. The current density vs. electric field (J-E) characteristics was measured at different temperatures (300–673 K). Detailed J-E analysis revealed an ohmic conduction at the low applied electric field (<65 kV/cm) within the entire temperature range. However, at high electric field (>65 kV/cm), space charge limited conduction (SCLC) mechanism was found to be dominating in low measurement temperature (300–473K), whereas, a transition from SCLC mechanism to Poole-Frenkel mechanism was observed with further increment in the temperature beyond 473 K. The temperature invariant dielectric tunability (nr ∼10%) and low zero electric field leakage current density (J ∼10−7A/cm2) at 673 K temperature, demonstrates the feasibility of nc-SiCN thin films for tunable device applications in the high-temperature and harsh environment.
      Graphical abstract image

      PubDate: 2018-01-10T07:07:39Z
  • Electronic transport study of PbSe pellets prepared from self-assembled
           2D-PbSe nanostructures
    • Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): E. Díaz-Torres, A. Flores-Conde, A. Ávila-García, M. Ortega-López
      This work presents a study of the electronic transport properties of PbSe pellets fabricated starting of PbSe nanostructures that exhibited a flake-like 2D morphology, which were synthesized by the co-precipitation method. Seebeck coefficient measurements revealed that the PbSe sample displays n-type conductivity, a maximum Seebeck coefficient of −512.6 μV/K around 380 K, and that the carriers scattering is dominated by acoustic and optical phonons. The Fermi level dependence on the temperature and the band gap energy are also reported. Interestingly, size-dependent confinement effects due probably to the reminiscent PbSe 2D character could be evidenced.

      PubDate: 2018-01-10T07:07:39Z
  • High efficiency screen-printed n-type silicon solar cell using
           co-diffusion of APCVD boron emitter and POCl3 back surface field
    • Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): Kyungsun Ryu, Keeya Madani, Ajeet Rohatgi, Young-Woo Ok
      We present the fabrication and analysis of Passivated Emitter and Rear Totally Diffused (PERT) solar cells on n-type silicon using a co-diffusion process. In a single high temperature step, a BSG/SiOx stack deposited by APCVD and a POCl3 back surface field diffuse into the wafer to form the boron doped emitter and phosphorus doped back surface field. The SiOx layer on top of BSG acts as a masking layer to prevent cross-doping of phosphorus as well as a blocking layer for boron out-diffusion. This resulted in an initial sheet resistance of 76 Ω/□ with good uniformity and a final p+ emitter sheet resistance of 97 Ω/□ after boron rich layer removal. Additionally, bulk lifetime was investigated before and after the high temperature step that resulted in an increase from 1.2 ms to 1.5 ms due to a POCl3 gettering effect. A peak cell efficiency of 20.3% was achieved and each recombination component in terms of saturation current density was calculated and analyzed to understand the cell for further efficiency enhancement.

      PubDate: 2018-01-10T07:07:39Z
  • Micromagnetic study of domain wall depinning driven by nanosecond current
           pulse in notched Permalloy nanowires
    • Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): Dede Djuhana, Candra Kurniawan, Dong-Hyun Kim
      The complete understanding of domain wall (DW) dynamics is important in the design of future spintronic devices. The characteristics of faster time-scale and lower current amplitude to move DW along nanowire are crucial in fabrication upgrade. In this study, we have investigated depinning behavior of magnetic domain wall triggered by nanosecond current pulse in notched Permalloy nanowires by means of micromagnetic simulation. We introduced double-triangular notch as the constrictions in the nanowire. The non-adiabaticity of the spin-transfer-torque is considered in simulation by varying the non-adiabatic constant (β) value. We observed that the depinning current density (J d) was not significantly affected by β for notch size (s) < 50 nm. Interestingly, we found that the depinning time (t d) for β ≥ 0.04 was slightly constant for all the cases with s > 70 nm, where the DW structure was kept to be a transverse structure during the depinning process. The broadly applicable depinning behavior is considered to contribute to the development of high-speed memory storage devices based on magnetic domain wall.

      PubDate: 2018-01-10T07:07:39Z
  • Effects of heating rate on the magneto-optical properties of
           bismuth-substituted yttrium iron garnet films prepared via modified
           metal-organic decomposition
    • Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): Viet Dongquoc, Rambabu Kuchi, Phuoc Cao Van, Soon-Gil Yoon, Jong-Ryul Jeong
      This work investigated the effects of heating rate and annealing on the magneto-optical properties of bismuth-substituted yttrium iron garnet (Bi-YIG) thin films on glass and (111)-oriented single-crystalline gadolinium gallium garnet (GGG) substrates fabricated by metal-organic decomposition (MOD). We modified the MOD method by eliminating the pre-annealing process. We performed annealing at various temperatures to determine the optimal temperature for obtaining the Bi-YIG phase. We then annealed at the optimized temperature using various heating rates. The optimal conditions were annealing for 1 h at 750 °C at a heating rate of 30 °C/min on GGG to obtain highly crystallized fine grains. The Faraday rotation for this film was about −10.5°/μm. The optimized heating rate enhanced the magneto-optical properties due to improved crystallinity and saturated magnetization. The Bi-YIG thin films prepared by this prescribed MOD method exhibited excellent magneto-optical performance and are potential candidates for applications in optical devices.

      PubDate: 2018-01-10T07:07:39Z
  • Elucidating iron doping induced n- to p- characteristics of Strontium
           titanate based ethanol sensors
    • Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): Neha Sarin, Monu Mishra, Govind Gupta, Ivan P. Parkin, Vandna Luthra
      A series of pure and iron doped strontium titanate, (SrFexTi1-xO3; x = 0, 0.1 and 0.2) powders were synthesized, characterized and used to fabricate ethanol sensors for low concentration. X-Ray Diffraction (XRD) technique was used to confirm the single phase formation. Microstructural properties of the powders were investigated using scanning electron microscopy (SEM). Electrical conductivity of all the samples at room temperature (RT) was measured. Sensors were optimized for best responsiveness by varying the operating temperature from 350 °C to 500 °C.The sensor with doping x = 0.2 exhibited best sensing response at 400 °C for ethanol gas. The undoped sensor demonstrated a decrease in resistance on exposure to ethanol gas whereas Fe-doped sensors showed increase in resistance. The doping induced changeover from n to p behavior in the sensing response on doping has been investigated and corroborated with an observed shift in the Fermi level position by X-ray photoelectron spectroscopy (XPS). The disparity in gas sensing response clearly demonstrates inter-connection of multiple influencing factors such as electrical conductivity, morphology, porosity and change in chemical composition on doping. The sensors were exposed to ethanol, nitrogen dioxide, carbon monoxide, butane gases at concentration between 5 ppm and 50 ppm. The sensor exhibited much reduced relative response to all gases other than ethanol which can be utilized for wide range of applications.

      PubDate: 2018-01-10T07:07:39Z
  • Roughness influence on the sheet resistance of the PEDOT:PSS printed on
    • Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): Rogério M. Morais, Maykel S. Klem, Maíza S. Ozório, Tiago C. Gomes, Neri Alves
      The use of paper as a platform to manufacture organic electronic devices, electronic paper, has expanding potential for many applications because of several properties offered. In this work, we show a study of PEDOT:PSS printed by inkjet on bond paper, vegetal paper and sheets of PET. The relation between the surface density of the deposited material, morphology and resistivity was investigated for samples printed with a commercial Hewlett-Packard(HP)® printer and Microsoft Word® software. The amount of material deposited, i.e. surface density, was controlled using the print number in the same position and changing the gray scale used in the image formation. Changing the surface density of printed PEDOT:PSS, it is possible to produce a continuous film permeating the papers fibers. Sheet resistances obtained, when 7.0 mg cm−2 of PEDOT:PSS were deposited on the surfaces, were: (a) 413.2 kΩ/Sq for bond paper, (b) 5.6 kΩ/Sq for vegetable paper and (c) 2.3 kΩ/Sq for PET. The exponential dependence of sheet resistance with the surface density of printed material allows us to evaluate the strong influence of substrate roughness on PEDOT:PSS conductivity and to predict, for each one, conditions to minimize it.

      PubDate: 2018-01-10T07:07:39Z
  • Local symmetry distortion-induced enhancement of upconversion luminescence
           in Gd2O3:Ho3+/Yb3+/Zn2+ nanoparticles for solid-state lighting and
    • Abstract: Publication date: Available online 9 January 2018
      Source:Current Applied Physics
      Author(s): Peng Du, Eun-Joong Kim, Jae Su Yu
      The Ho3+/Yb3+/Zn2+-tridoped Gd2O3 nanoparticles were prepared by a simple urea-based homogeneous precipitation method. Under near-infrared (NIR) light excitation, all the synthesized nanoparticles exhibit bright green and red upconversion (UC) emissions corresponding to the intra-4f transitions of Ho3+ ions and the UC mechanism is found to be a two-photon process. With the introduction of Zn2+ ions, not only the local symmetry surrounding the dopants is decreased, but also the UC emission intensity is also enhanced, which is further verified by the Judd-Ofelt theory. The temperature-dependent UC emission spectra were recorded to examine the thermal stability of the final products. From theoretical calculations, the activation energy is demonstrated to be about 0.18 eV. A novel green light-emitting diode device, which consists of the resultant nanoparticles and a NIR chip, was fabricated to state their suitability for solid-state lighting. Meanwhile, the synthesized nanoparticles exhibit low cytotoxicity in various cell lines, suggesting their potential applications in in vivo UC luminescence imaging. Additionally, the applicability of the Ho3+/Yb3+/Zn2+-tridoped Gd2O3 nanoparticles for in vivo bioimaging applications was also analyzed.

      PubDate: 2018-01-10T07:07:39Z
  • Effect of electrochemical reduction on the structural and electrical
           properties of anodic TiO2 nanotubes
    • Abstract: Publication date: Available online 9 January 2018
      Source:Current Applied Physics
      Author(s): Muhammad Asim Rasheed, Kamran Ahmad, Nilem Khaliq, Yaqoob Khan, Muhammad Aftab Rafiq, Abdul Waheed, Attaullah Shah, Arshad Mahmood, Ghafar Ali
      The effect of electrochemical reduction on the structural and electrical properties of amorphous as well as annealed TiO2 nanotubes (TNTs) is investigated under ambient conditions. TNTs were prepared by anodizing titanium sheet in ethylene glycol electrolyte containing NH4F and de-ionized water at 40 V for 6 h. Electrochemical reduction is carried out in 1 M aqueous KOH solution for ∼15 s at 3 V. TNTs are characterized by SEM, XRD, XPS and impedance spectrometer. XRD results confirm an increase in d-spacing for (101) and (200) planes, after electrochemical reduction. XPS data reveal that electrochemical reduction produced prominent shifts of ∼0.7–1.0 eV in the binding energies of TNTs. Interestingly, these shifts recover completely (in case of amorphous TNTs) and partially (in case of anatase TNTs) within ∼7 days after reduction process due to oxygen uptake. Partial recovery in the binding energies of anatase TNTs is due to the fact that the oxygen vacancies are thermodynamically more stable compared to amorphous TNTs. Similarly, the electrochemical reduction process decreases the impedance values of TNTs by more than three orders of magnitudes (from MΩ to kΩ). The impedance values also recover to the similar values before reduction in a span of ∼7days.

      PubDate: 2018-01-10T07:07:39Z
  • Ferroelectric polarization effect on hysteresis behaviors of single-walled
           carbon nanotube network field-effect transistors with lead
           zirconate-titanate gating
    • Abstract: Publication date: Available online 9 January 2018
      Source:Current Applied Physics
      Author(s): Yilin Sun, Dan Xie, Ruixuan Dai, Mengxing Sun, Weiwei Li, Tianling Ren
      We report the fabrication of single-walled carbon nanotube (SWCNT) network transistors by ferroelectric Pb(Zr0.4Ti0.6)O3 (PZT) bottom-gating and investigate the polarization effects of PZT on the transport properties of the transistor device. Our devices exhibit typical p-channel transistor characteristics and a large hysteresis loop with high ON/OFF current ratio and large ON current as well as memory window (MW) measured up to 5.2 V. The origin of clockwise hysteresis is attributed to ferroelectric polarization modulated charge trapping/de-trapping process in the interface states between SWCNT networks and PZT. The retention time about 104s with two high stable current states preliminarily demonstrates great potential for future non-volatile memory applications based on such SWCNT/PZT hybrid systems.

      PubDate: 2018-01-10T07:07:39Z
  • Facile preparation and performance of novel high-TC
           xBi(Ni1/2Ti1/2)O3-(1-x)Pb(Zr1/2Ti1/2)O3 piezoceramics
    • Abstract: Publication date: Available online 5 January 2018
      Source:Current Applied Physics
      Author(s): Wanwan Ji, Shuai Feng, Bijun Fang, Xiangyong Zhao, Shuai Zhang, Jianning Ding, Haosu Luo
      High Curie temperature (TC) xBi(Ni1/2Ti1/2)O3-(1-x)Pb(Zr1/2Ti1/2)O3 (xBNT-(1-x)PZT, BNT-PZT) piezoelectric ceramics were prepared by the conventional ceramic processing. The composition-induced morphotropic phase boundary (MPB) and its influences on structure and electrical performance were investigated. The synthesized BNT-PZT ceramics exhibit rather pure perovskite structure, and densified microstructure morphology with uniform elementals distribution in both grains and grain boundaries. With increasing the content of Bi(Ni1/2Ti1/2)O3 (BNT), crystal structure of the BNT-PZT ceramics transform from tetragonal phase to rhombohedral phase, and dielectric response peaks change from narrow shape to very broad shape but all presenting dielectric frequency dispersion. The diffused and relaxation dielectric behavior can be fitted well by the quadratic law, and the Vogel-Fulcher law fitting provides additional information on the relaxation characteristic. The MPB effects are confirmed further by ferroelectric and piezoelectric properties measurements. High-TC combined with excellent piezoelectric performance can be realized in the BNT-PZT system, which presents promising applications in geothermal exploration, aerospace and related elevated temperatures fields.

      PubDate: 2018-01-10T07:07:39Z
  • Formation of graphene on amorphous SiC film by surface-confined heating
           with electron beam irradiation
    • Abstract: Publication date: Available online 29 December 2017
      Source:Current Applied Physics
      Author(s): Hanbyul Jin, Jung-Yong Lee, Junhyung Kim, Sungchul Jung, Kyuhyung Mo, Kibog Park
      It is demonstrated experimentally that graphene can form on the surface of an amorphous SiC film by irradiating electron beam (e-beam) at low acceleration voltage. As the electron irradiation fluency increases, the crystallinity and uniformity of graphene improve, which is confirmed by the changes of the measured Raman spectra and secondary electron microscopy images. Due to the shallow penetration depth of e-beam with low acceleration voltage, only the region near the surface of SiC film will be heated by the thermalization of irradiated electrons with multiple scattering processes. The thermalized electrons are expected to weaken the bond strength between Si and C atoms so that the thermal agitation required for triggering the sublimation of Si atoms decreases. With these assistances of irradiated electrons, it is considered that graphene can grow on the surface of SiC film at temperature reduced substantially in comparison with the conventional vacuum annealing process.

      PubDate: 2018-01-10T07:07:39Z
  • Effect of adding non-ferromagnetic nanoparticles to grain boundary on
           coercivity of sintered Nd-Fe-B magnet
    • Abstract: Publication date: Available online 27 December 2017
      Source:Current Applied Physics
      Author(s): Pham Thi Thanh, Nguyen Van Duong, Nguyen Hai Yen, Nguyen Huy Ngoc, Nguyen Mau Lam, Kieu Xuan Hau, Seong Cho Yu, Nguyen Huy Dan
      In this work, we investigated the influence of additional compounds of Nd-Cu-Al, Dy-Nb-Al, Dy-Zr-Al and Nb-Cu-Al on coercivity of sintered Nd-Fe-B magnets. The additional nanoparticles with size in the range of 40–80 nm was mixed with the micrometer Nd-Fe-B powder before sintering process. The results show that the coercivity of the sintered Nd-Fe-B magnets can be improved by introducing additional nanoparticles to their grain boundaries. The improvement of the coercivity of the magnets is clearly dependent on composition and fraction of the additional compounds. While the Dy-Nb-Al, Dy-Zr-Al and Nb-Cu-Al compounds degrade the coercivity of the sintered Nd-Fe-B magnets, the Nd-Cu-Al nanoparticles considerably improve this quantity. The coercivity the sintered Nd16.5Fe77B6.5 magnets has been enhanced about 40% by adding 3 wt% of the Dy-free compound of Nd40Cu30Al30.

      PubDate: 2018-01-10T07:07:39Z
  • Potential of metal–fullerene hybrids as strong nanocarriers for cytosine
           and guanine nucleobases: A detailed DFT study
    • Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): Ali Shokuhi Rad, Sadegh Mehdi Aghaei
      In this article, the adsorption of cytosine and guanine molecules on the surface of Cr-doped C20 fullerene (C19Cr) and Ni-doped C20 fullerene (C19Ni) are studied using first-principles density functional theory (DFT) calculations. In order to thoroughly comprehend the influences of the molecules on the metal-fullerene complexes, the geometric parameters, the binding energies, transferred charges, the magnitude of dipole moments, thermochemical parameters, frontier molecular orbitals, and the global indices of activities are calculated. The results highlighted that the interactions of both cytosine and guanine molecules with metal-fullerene complexes are highly exothermic, suggesting that these molecules might be chemisorbed on their adsorbents. The C19Cr exhibits a better adsorption behavior toward the molecules compared to C19Ni, and cytosine has the higher binding energies with metal-fullerene complexes in comparison with guanine. Further analyses showed that the C19Cr experiences significant changes in its electronic properties upon adsorption of the cytosine molecule. However, the small variations in the electronic properties of C19Ni after complexation with guanine indicate that this complex is not sensitive to the guanine. Furthermore, the results of frontier molecular orbital reveal the strong (moderate) interactions between the C19Cr with the cytosine (guanine) molecule and moderate (weak) interactions between the C19Ni with the cytosine (guanine) molecule. Therefore, the C19Cr and C19Ni have moderate sensitivities to cytosine and guanine molecules. More excitingly, our findings divulge promising potential of the Cr-fullerene complex as a biochemical adsorbent for cytosine.
      Graphical abstract image

      PubDate: 2017-12-27T06:12:27Z
  • Ultrasmall iron oxide nanoparticles: Magnetic and NMR relaxometric
    • Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): Branka Babić-Stojić, Vukoman Jokanović, Dušan Milivojević, Miroslav Požek, Zvonko Jagličić, Darko Makovec, Nataša Jović Orsini, Mirjana Marković, Katarina Arsikin, Verica Paunović
      Ultrasmall iron oxide (USPIO) nanoparticles, with diameter mostly less than 3 nm dispersed in an organic carrier fluid were synthesized by polyol route. The evolution of ZFC-FC magnetization curves with temperature, as well as the shift of the ac susceptibility peaks upon changing the frequency, reveal that the nanoparticles in the fluid are non-interacting and superparamagnetic with the blocking temperature T B ∼10 K. The Mössbauer spectra analysis proposed the core/shell structure of the nanoparticles consisting of stoichiometric γ-Fe2O3 core and non-stoichiometric shell. The nanoparticle surface layer has a great influence on their properties which is principally manifested in significant reduction of the magnetization and in a large increase in magnetic anisotropy. Magnetic moments do not saturate in fields up to 5 T, even at the lowest measured temperature, T = 5 K. The average magnetic particle diameter is changed from 1.3 to 1.8 nm with increasing magnetic field from 0 to 5 T which is noticeably smaller than the particle sizes measured by TEM. The estimated effective magnetic anisotropy constant value, K eff = 2 × 105 J/m3, is two orders of magnitude higher than in the bulk maghemite. Measurements of the longitudinal and transverse NMR relaxivity parameters on water diluted nanoparticle dispersions at 1.5 T gave the values r 1 = 0.028 mmol−1 s−1, r 2 = 0.050 mmol−1 s−1 and their ratio r 2/r 1 = 1.8. Continuous increase of the T 1-weighted MRI signal intensity with increasing Fe concentration in the nanoparticle dispersions was observed which makes this ferrofluid to behave as a positive T 1 contrast agent.

      PubDate: 2017-12-27T06:12:27Z
  • Electronic structure and magnetic properties of BaTi1-xMnxO3
    • Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): N.V. Dang, N.T. Dang, T.A. Ho, N. Tran, T.L. Phan
      The electronic structure and magnetic properties of polycrystalline BaTi1-xMnxO3 (x = 0–0.1) compounds prepared by solid-state reactions were studied. The results revealed that the increase in Mn content (x) did not change the oxidation numbers of Ba (+2) and Ti (+4) in BaTi1-xMnxO3. However, there is the change in Mn valence that Mn3+,4+ ions coexist in the samples with x = 0.01–0.04 while Mn4+ ions are almost dominant in the samples with x = 0.06–0.1. We also point out that Mn3+ and Mn4+ ions substitute for Ti4+ and prefer locating in the tetragonal and hexagonal BaTiO3 structures, respectively, in which the hexagonal phase constitutes soon as x = 0.01. Particularly, all the samples exhibit room-temperature ferromagnetism. Ferromagnetic order increases with increasing x from 0 to 0.02, but decreases as x ≥ 0.04. We think that ferromagnetism in BaTi1-xMnxO3 is related to lattice defects and/or exchange interactions between Mn3+ and Mn4+ ions.

      PubDate: 2017-12-27T06:12:27Z
  • Effect of transition metal oxidation state on crystal structure and
           magnetic ordering in frustrated ABaM4O7 systems (A= Y, Ca; M= Co, Fe):
           X-ray diffraction, soft X-ray absorption, and magnetization studies
    • Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): V.R. Galakhov, D.I. Turkin, V.V. Mesilov, S.N. Shamin, G.V. Bazuev, K. Kuepper
      We present X-ray diffraction patterns, soft Ca, Co, and Fe L 2,3 absorption spectra, magnetic susceptibility, and temperature dependent magnetization measurements in order to characterize ABaM 4O7 solid solutions A = Y, Ca; M = Co, Fe). Cobalt ions are in 2 + and high-spin 3 + oxidation states. In the iron-doped solid solutions, Fe ions were found to be trivalent. Doping with Fe ions leads to a decreasing amount of Co3+ ions. Magnetic properties of the studied samples showed a spin-glass behavior. Negative values of the Curie–Weiss temperatures indicated the predominance of antiferromagnetic exchange interactions. The freezing point of the magnetic moments is 51 K and does not vary with the amount of Fe doping.
      Graphical abstract image

      PubDate: 2017-12-27T06:12:27Z
  • Synthesis and characterization of nitrogen-doped TiO2 coatings on reduced
           graphene oxide for enhancing the visible light photocatalytic activity
    • Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): Yifan Zhang, Hye Mee Yang, Soo-Jin Park
      Nitrogen-doped TiO2 coatings on reduced graphene oxide were prepared via a sonochemical synthesis and hydrothermal process. The nanocomposites showed improved photocatalytic activity due to their large specific surface areas (185–447 m2/g), the presence of TiO2 in the anatase phase, and a quenched photoluminescence peak. In particular, GN3-TiO2 (nitrogen-doped TiO2 coatings on rGO with 3 ml of titanium (IV) isopropoxide) exhibited the best photocatalytic efficiency and degradation rate among the materials prepared. With nitrogen-doped on the reduced graphene oxide surface, the photocatalytic activity is enhanced approximately 17.8 times compared to that of the pristine TiO2. The dramatic enhancement of activity is attributed to the nitrogen contents and rGO effectively promoting charge-separation efficiency and providing abundant catalytically active sites to enhance the reactivity. The composites also showed improved pollutant adsorption capacity, electron–hole pair lifetime, light absorption capability, and absorbance of visible light.
      Graphical abstract image

      PubDate: 2017-12-27T06:12:27Z
  • Electronic structure of the PLD grown mixed phase MoS2/GaN interface and
           its thermal annealing effect
    • Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): Arun Barvat, Nisha Prakash, Gaurav Kumar, Dilip K. Singh, Anjana Dogra, Suraj P. Khanna, Prabir Pal
      We report the electronic structure of Molybdenum disulfide (MoS2) ultrathin 2D films grown by pulsed laser deposition (PLD) on top of GaN/c-Al2O3 (0001) substrates annealed up to 550 °C in an ultrahigh vacuum. Our X-ray photoemission spectroscopy (XPS) study shows that the grown films are mixed phase character with semiconducting 2H and metallic 1T phases. After ultrahigh vacuum (UHV) annealing, the 1T/2H phase ratio is significantly modified and film-substrate bonding becomes the leading factor influencing variation of mixed phase compositions. The semiconducting phase is partially transformed to metallic phase by thermal annealing; suggesting that the metallic phase observed here may indeed have more stability compared to the semiconducting phase. The notable enhancement of the 1T/2H ratio induces significant changes in Ga 3d core level spectra taken from bare GaN and MoS2/GaN sample. The impact of S and/or Mo atoms on the Ga core level spectra is further pronounced with the thermal annealing of grown films. The analysis shows that an enhancement of 1T metallic phase with thermal annealing in MoS2 layers is manifested by the occurrence of new spectral component in the Ga 3d core level spectra with the formation of Ga-S adlayer interaction through the Ga bonding in defect assisted GaN structure.

      PubDate: 2017-12-27T06:12:27Z
  • Efficient implementation of multiple drive-in steps in thermal diffusion
           of phosphorus for PERC solar cells
    • Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): Dongchul Suh
      N-type phosphorus diffusion in silicon using phosphorus oxychloride, POCl3, has been widely used in the production of p-type silicon solar cells. The thermal diffusion process in a furnace generally involves two steps: pre-deposition and drive-in. The phosphorous doping by thermal diffusion often shows high surface concentrations, leading to an increase in charge recombination, which should be inhibited in order to fabricate high efficiency silicon solar cells. In this study, we investigate the influence of 3 drive-in steps at sequentially increasing temperatures during the POCl3 diffusion on the emitter performance. As a result, it was found that the kink region was made shorter while maintaining surface concentration for a good metal contact without losing its passivation quality. This result is attributed to the higher active dopant concentration of the 3 drive-in step samples, leading to a lower series resistance and higher fill factor in the PERC solar cells. The results show that slight changes in the PSG process conditions can contribute to the improvement of high efficiency solar cells.

      PubDate: 2017-12-27T06:12:27Z
  • Investigation of the interstitial oxygen behaviors in vanadium alloy: A
           first-principles study
    • Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): Xingming Zhang, Yifan Li, Qiaoling He, Ruilian Li, Lei Deng, Liang Wang, Xunlin Liu, Jianfeng Tang, Huiqiu Deng, Wangyu Hu
      This study aims at characterizing the interstitial Oxygen (O) behaviors in the Vanadium (V) Alloy by means of the first-principles calculations. For this, the interations between vacancy (Vac) and O interstitil atom are studied in detail to obtain the binding energies and stable structures of the complexes. It can be seen that monovacancy binding with two O atoms occupied the opposing octahedral stie are particularly stable, and is liable to form VacO2 cluster in the V alloys. According to the mass action analysis, the predicted temperature dependence of the concentration for VacO n complexes are presented. Apart from monovacancy, we also consider the trapping behavior of vacancy cluster on the O atoms. The results also prove that one vacancy can trap two O atoms in the V alloys. Based the diffusion theory, we obtain the diffusion coefficients as a function of temperature with or without the vacancy effect in the V alloys. The predicted O diffusion coefficients in defect-free V alloys from our first-principles calculations are in excellent ageement with the experimental data, meanings that the vacancy-limited mechanism does not play the key role for O diffusion in V alloys. Regarding the interactions between vacancy, solutes and O atom, combining with the diffusion barriers of O affected by vacancy and solute, we infer the formation mechanism of the precipitates in the V alloys.

      PubDate: 2017-12-27T06:12:27Z
  • Characterization of CBO and defect states of CZTSe solar cells prepared by
           using two-step process
    • Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): SeongYeon Kim, JunHo Kim, Tanka R. Rana, Kang-Woo Kim, Myeung-Hoi Kwon
      We fabricated kesterite Cu2ZnSnSe4 (CZTSe) solar cells and studied device characteristics, where CZTSe absorbers were made by using two-step process. First, we deposited precursor CZTSe films with spin-coating or sputtering, and performed sulfurization and subsequent selenization. To complete the device, we applied In2S3 as a buffer layer. We obtained power conversion efficiency (PCE) of 4.18% with spin-coated CZTSe absorber and 5.60% with sputtered CZTSe absorber. Both devices showed deep defects in the bulk and strong interface recombinations near the pn junction. In addition, we observed red-kinks in the current density-voltage (J-V) curves for both devices under the filtered light illumination (>660 nm), which is attributed to large conduction band offset (CBO) between the CZTSe absorber and the buffer layer and defect states in the buffer/CZTSe absorber or in the buffer. The red-kink was also observed in CZTSe (PCE of 7.76%) solar cell with CdS buffer. Hence, to enhance the PCE with CZTSe absorber, along with suppression of deep defects which act as recombination center, optimization of CBO between absorber and buffer is also required.

      PubDate: 2017-12-27T06:12:27Z
  • First-principles study on the electronic structure and optical properties
           of La0.75Sr0.25MnO3-σ materials with oxygen vacancies defects
    • Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): Jun Jiang, Qing-Ming Chen, Xiang Liu
      The electronic structure and optical properties of La0.75Sr0.25MnO3-σ (LSMO3-σ ) materials with 1 × 1 × 4 orthorhombic perovskite structure were performed by first-principles calculation. The structural changing of LSMO3 (ideal structure, σ = 0) was not obvious under generalized gradient approximation (GGA) and GGA + U arithmetic. On the contrary, the structural changing of LSMO3-σ (σ = 0.25, with oxygen vacancies defects in the z = 0, c/8, c/6, c/4, and c/2) with GGA + U were more obvious than the result of ideal. This structural distortion induced distinct changing in density of states (DOS) for LSMO3-σ materials. Oxygen vacancy defects caused a shift of the total density of states (TDOS) features toward low binding energies and LSMO3-σ keep half-metal properties as well as LSMO3 ideal structure. In addition, the hybridization between the Mn-e g and O-2p orbital was weakened and the partial density of states (PDOS) of Mn indicated a strong d-d orbital interaction. By the result of oxygen vacancy formation energy, oxygen vacancy defects can be more easily formed in La-O layers (z = 0 and c/6) to compare with other layers (z = c/8, c/4 and c/2). The calculation result of optical properties suggested that the ideal LSMO could be produced strong absorption in the range of ultraviolet and visible light, while the LSMO3-σ with oxygen vacancies defects were presented weak absorption in the range of visible light.

      PubDate: 2017-12-27T06:12:27Z
  • Molecular dynamics simulation study on the structural properties of poly
           (ethylene terephthalate) under uniaxial extension and thermal shrinkage
    • Abstract: Publication date: January 2018
      Source:Current Applied Physics, Volume 18, Issue 1
      Author(s): Ki Chul Kim, Seung Soon Jang
      In thermal shrinkage process for polyethylene terephthalate (PET) films, PET film is uniaxially stretched and then thermally relaxed. We investigate the effect of heat relaxation temperature on the thermal shrinkage of uniaxially stretched PET film using molecular dynamics simulation method. Through our investigation, we find that the thermal shrinkage ratio of the amorphous PET film is reduced as a function of heat relaxation temperature, whereas the skirt ratio is weakly correlated with the heat relaxation temperature, exhibiting the most negative skirt ratio in the case of the highest thermal shrinkage ratio. Our analysis on the PET film at molecular level further verifies that the trans-gauche transformation observed in ethylene glycol units during the simulated process is a driving force for the thermal shrinkage of uniaxially stretched PET systems.
      Graphical abstract image

      PubDate: 2017-12-27T06:12:27Z
  • Sr2FeMoO6 nanosized compound with dielectric sheaths for magnetically
           sensitive spintronic devices
    • Abstract: Publication date: January 2018
      Source:Current Applied Physics, Volume 18, Issue 1
      Author(s): Nikolay Kalanda, Dong-Hyun Kim, Sergey Demyanov, Seong-Cho Yu, Marta Yarmolich, Alexander Petrov, Suhk Kun Oh
      Single-phase agglomerated Sr2FeMoO6-δ powders with the iron and molybdenum cations superstructural ordering of 88% were synthesized by sol-gel technique from the Sr(NO3)2 and Fe(NO3)3·9H2O solutions with pH = 4. The ultrasound dispersion enabled us to obtain 75 nm grains. Powders were pressed with 4 GPa to receive the ceramics. The additional annealing at 700 K promoted the appearance of 7.5% SrMoO4 phase. The nanocomposite with dielectric sheaths around the grains was obtained. Magnetization temperature dependences in zero-field cooled mode revealed inhomogeneous magnetic states. At temperature below 19 K, the superparamagnetic state is observed. Temperature increase leads to a realization of the stable superparamagnetic and metastable ferrimagnetic states, blocked by magnetic anisotropy energy. The resistivity temperature dependences have the semiconducting conductivity type. The charge transfer due to the hopping conductivity on the localized states in the energy band near the Fermi level dominates at 260–300 K. At 130–200 K the charge transfer is realized by electrons tunneling through the energy barrier. The electrons inelastic tunneling on conducting channels between grains, through the localized states in the dielectic interlayer dominates at low temperatures. The resistivity decreases in magnetic fields and the negative tunneling magnetoresistive effect reaching 41% occurs.
      Graphical abstract image

      PubDate: 2017-12-27T06:12:27Z
  • Hydrostatic pressure and magnetic field effect on the excited states in
           inverse parabolic quantum dot
    • Abstract: Publication date: January 2018
      Source:Current Applied Physics, Volume 18, Issue 1
      Author(s): S.A. Safwan, Assma Saleh, Hekmat M. Hassanein, Nagwa El Meshed
      The hydrostatic pressure (P) influence of the degenerate energy states inside an inverse parabolic quantum dot (IPQD), with and without an external magnetic field, was performed within the frame of the effective mass approximation. Our theoretical results showed that the effect of relatively high pressure clearly appeared to induce a crossing between the excited states in the strong confinement region. But in the weak confinement region, such crossing disappeared and, in addition, the excited states got reordered. In the presence of an external magnetic field the hydrostatic pressure modified the crossing points of the degenerate states. We investigated the electron-heavy hole transition energy. It displayed a blue shift with increasing the pressure values and the magnetic field strength. But it showed an adhesive red shift by increasing the IPQD size.

      PubDate: 2017-12-27T06:12:27Z
  • Pressure-induced insulator-metal transition in Ca2Ru0.92Fe0.08O4
           investigated by infrared microspectroscopy
    • Abstract: Publication date: January 2018
      Source:Current Applied Physics, Volume 18, Issue 1
      Author(s): S.H. Park, M.S. Kim, G. Cao, K.I. Kim, B.N. Chae, J.S. Lee
      We investigated pressure-induced insulator-metal transition in Ca2Ru0.92Fe0.08O4 by using infrared microspectroscopy. As the pressure is increased up to 1.7 GPa, we observed a large increment of the reflectivity in the entire mid-infrared range. Accompanied by such a clear signature of the insulator-metal transition, we found an evidence of the structural transition from the frequency shift of the Ru-O stretch phonon mode which is attributed to the shortening of the in-plane Ru-O bond length. When we compared these pressure-dependent changes with the corresponding temperature-dependent results, we found that the pressure-induced metallic state has a higher reflectivity as well as the higher phonon frequency. Indeed, it turns out that the pressure-induced metallic state of Ca2Ru0.92Fe0.08O4 looks very similar with the metallic state of Sr-substituted Ca2RuO4 not only in the reflectivity level but also in the phonon frequency. This suggests that the electronic properties are closely related to the structural degree of freedom, and the pressure can be a useful parameter to induce the transitions from the Mott-insulator to the metal and further to the superconductor as observed for Sr2RuO4.

      PubDate: 2017-12-27T06:12:27Z
  • Effects of oxygen deficiency on the acoustic anomalies and phase
           transition behaviors of barium titanate single crystals
    • Abstract: Publication date: January 2018
      Source:Current Applied Physics, Volume 18, Issue 1
      Author(s): Jae-Hyeon Ko, Seonhyeop Shin, Moongyu Jang, Choong Jae Won, Namjung Hur
      The acoustic behaviors of oxygen-reduced barium titanate (BaTiO3-δ ) single crystals with δ∼0.04 were investigated as a function of temperature by using Brillouin spectroscopy. The longitudinal acoustic mode of the moderately-reduced BaTiO3 (BTO) showed two pronounced anomalies at approximately 112 °C and −11 °C, which correspond to the cubic-tetragonal and tetragonal-orthorhombic phase transition temperature, respectively. These temperatures were lower by more than 10 °C compared to those of the pure BaTiO3 suggesting that the disorder introduced by oxygen vacancies lowers the phase transition temperatures. The paraelectric phase of the reduced BaTiO3 were characterized by substantial softening of the longitudinal acoustic mode and the growth of central peaks centered at zero frequency. These anomalies were observed in a certain temperature range above the Curie temperature, indicating that pretransitional precursor polar clusters exist in the cubic phase and that their dynamics are responsible for the acoustic anomalies caused by electrostrictive coupling between the strain and the polarization. The relaxation time of the precursor polar clusters derived from the central peak exhibited a critical slowing-down behavior showing that their dynamics becomes more sluggish as temperature approaches the Curie point.

      PubDate: 2017-12-27T06:12:27Z
  • Field-controllable injection of virtual magnetic domain wall in discrete
           magnetic nanodot chains
    • Abstract: Publication date: January 2018
      Source:Current Applied Physics, Volume 18, Issue 1
      Author(s): Xiao-Ping Ma, Seon-Dae Kim, Hong-Guang Piao, Dong-Hyun Kim
      Periodic injection behaviors of virtual magnetic domain wall (VDW) have been systematically investigated in asymmetrically shaped nanodot chains by means of micromagnetic simulations. Systematic investigation on a controllable VDW injection has been carried out. We demonstrate that precise control of VDW injection is achievable by using different nanodot shapes as well as by changing alternating magnetic field (AC field) profiles. The VDW position can be tuned by adjusting AC field frequency and amplitude. Field-controllable periodic VDW injection phenomenon is found to be sustainable over wide ranges of phase diagram spanned by AC field frequency and amplitude.

      PubDate: 2017-12-27T06:12:27Z
  • Enhanced and broadband absorber with surface pattern design for X-Band
    • Abstract: Publication date: January 2018
      Source:Current Applied Physics, Volume 18, Issue 1
      Author(s): Chenguang Wu, Shuwen Chen, Xisheng Gu, Renchao Hu, Shuomin Zhong, Guoguo Tan, Qikui Man, Chuntao Chang, Xinmin Wang, Run-Wei Li
      A broadband and thin-layer microwave absorber is designed based on surface pattern design made by carbonyl iron and rubber composite. The bandwidth with reflection less than −10 dB covers the full X-band owing to two absorption peaks appeared simultaneously in both the simulation results and experimental results. In this work, the power loss and power flow diagram were present by CST simulation, which clearly explain the broadband absorption caused by double λ/4 matching absorption and interfacial scattering synergistic effect. A facile splicing method was provided to extend the absorption bandwidth for the magnetic absorbing materials.

      PubDate: 2017-12-27T06:12:27Z
  • A comprehensive molecular dynamics study of a single polystyrene chain in
           a good solvent
    • Abstract: Publication date: January 2018
      Source:Current Applied Physics, Volume 18, Issue 1
      Author(s): Sajad Rasouli, Mohammad Reza Moghbeli, Sousa Javan Nikkhah
      In this study, molecular characteristics of polystyrene (PS) was calculated measuring its dilute-solution properties in toluene at 288.15 K via molecular dynamics (MD) simulations. The solution models consisted of PS chains with different number of repeating units all of which were in a dilute regime. In order to investigate the compatibility between the polymer and the solvent molecules, interaction energy and Flory-Huggins (FH) interaction parameter were estimated. The simulation results indicate that increasing the chain repeating units enhanced the interaction between the solute and the solvent. Additionally, the chain dimensions were evaluated calculating the radius of gyration (Rg) and end-to-end distance, r0. To determine the dynamic behavior of the chains in the solutions, mean square displacement (MSD) and diffusivity coefficient were calculated. The simulation results indicated that the chain rigidity at low molecular weight and chain flexibility with increasing the molecular weight influenced chains dynamic behavior and diffusivity. Moreover, radial distribution function (RDF) illustrated the effect of steric hindrance of the chains in dilute solution on capturing the solvent molecules. In addition, solution viscosity was calculated by performing non-equilibrium molecular dynamics simulation (NEMD). The obtained results of chain characteristics and viscosity showed a good agreement with experimental results published previously. This agreement confirms the accuracy of the applied simulation method to characterize the dilute solutions and the chains characteristics.
      Graphical abstract image

      PubDate: 2017-12-27T06:12:27Z
  • Performance assessment of Cu2SnS3 (CTS) based thin film solar cells by
    • Abstract: Publication date: January 2018
      Source:Current Applied Physics, Volume 18, Issue 1
      Author(s): Ejarder Sabbir Hossain, Puvaneswaran Chelvanathan, Seyed Ahmad Shahahmadi, Kamaruzzaman Sopian, Badariah Bais, Nowshad Amin
      A relative performance assessment of copper tin sulfide (CTS) thin film solar cells with different phases such as, cubic, tetragonal, and orthorhombic as an absorber layer has been carried out by AMPS-1D simulation software. Based on the proposed device architecture, the effects of thickness and carrier concentration for the absorber layer as well as the back metal contact with various work function are studied in order to improve the performance of CTS solar cell. It is found that 1018 cm−3 and 2500–3000 nm are optimum values for carrier concentration and thickness for all the investigated CTS absorber layer phases, respectively. On the other hand, back contact metal work function of 5.28 eV, 5.67 eV and 5.71 eV are identified to be the optimal values for cubic, tetragonal, and orthorhombic phases, respectively. We have analyzed in detail the output performance of CTS thin film solar cell with respect to its fabrication, which can serve a constructive research pathway for the thin film photovoltaic industry.

      PubDate: 2017-12-27T06:12:27Z
  • Electronic transport properties of graphene/Al2O3 (0001) interface
    • Abstract: Publication date: January 2018
      Source:Current Applied Physics, Volume 18, Issue 1
      Author(s): M.S. Gusmão, Angsula Ghosh, H.O. Frota
      The electronic structure and transport properties of a single layer of graphene (Gr) on α-Al2O3 surface are studied using the density functional theory (DFT). We present three models that take into account the atom at the termination of the alumina surface: a) Al atoms, with the center of the Gr hexagon directly over an Al atom; b) Al atoms, with a carbon directly positioned above an Al atom; c) oxygen atoms. Two processes of geometric optimization were used: (i) All the atoms of the supercell were allowed to move in accordance with the BFGS quasi-Newton algorithm; (ii) The atoms of the three topmost layers of the α-Al2O3 (0001) slab, including the C atoms, were allowed to move, whereas the atoms of the remaining layers were frozen in their respective atomic bulk positions. The first two models preserve qualitatively the electronic structure of the pristine Gr using the geometric optimization process (i) whereas, in the third model this structure was lost due to a significant charge transfer between the carbon and oxygen atoms irrespective of the optimization procedure. However, models (a) and (b) with the optimization (ii) reveal a p-type semiconducting behavior.

      PubDate: 2017-12-27T06:12:27Z
  • Formation of carbon composite structures on the Ge(110) surfaces
    • Abstract: Publication date: January 2018
      Source:Current Applied Physics, Volume 18, Issue 1
      Author(s): Karam Park, Sukmin Jeong
      We present our first-principles calculation of the adsorption and diffusion of a carbon adatom on the H-terminated and clean Ge(110) surfaces, which are essential processes in the nucleation and growth of a monolayer graphene on Ge(110) by chemical vapor deposition. On the H-terminated surface, the C adatom spontaneously substitutes H atom(s) to form a monohydride structure (CH) or a dihydride structure (CH2) and makes direct bonds with the substrate Ge atoms. The resulting diffusion barriers of the C adatom are 2.67 and 6.45 eV parallel to and perpendicular to the zigzag Ge chains of the surface, respectively. On the clean surface, the C adatom embeds into the zigzag Ge chain with nearly no barrier, kicking out a Ge atom out of the chain at the same time. The kicked-out Ge atom, instead of the C adatom, becomes a diffusion species with the barrier less than 0.63 eV. The formation of the C composite structures makes the C adatom difficult to diffuse both on the H-terminated and clean Ge(110) surfaces, which suggests that the nucleation and growth of the graphene islands from C seeds is much suppressed. We propose a growth mechanism of graphene monolayer going round the diffusion of the C adatoms on the Ge(110) surfaces.

      PubDate: 2017-12-27T06:12:27Z
  • Effect of AlN layer on the resistive switching properties of TiO2 based
           ReRAM memory devices
    • Abstract: Publication date: January 2018
      Source:Current Applied Physics, Volume 18, Issue 1
      Author(s): Bhawani Pratap Singh Rathore, Ravi Prakash, Davinder Kaur
      The present study reports the resistive switching behaviour in Titanium Dioxide (TiO2) material, with possible implementations in non volatile memory device. The Cu/TiO2/Pt memory device exhibit uniform and stable bipolar resistive switching behaviour. The current-voltage (I-V) analysis shows two discrete resistance states, the High Resistance State (HRS) and the Low Resistance State (LRS). The effect of an additional AlN layer in the resistive memory cell is also investigated. The Cu/TiO2/AlN/Pt device shows a multilevel (tri-state) resistive switching. Multilevel switching is facilitated by ionic and metallic filament formation, and the nature of the formed filaments is confirmed by performing a resistance vs. temperature measurement. The bilayer device shows improved reliability over the single layer device. The formation of high thermal conductive interfacial oxy-nitride (AlON) layer is the main reasons for the enhancement of resistive switching properties in Cu/TiO2/AlN/Pt cell. The performance of device was measured in terms of endurance and retention, which exhibits good endurance over 105 cycles and long retention time of 105 s at 125 °C. The above result suggests the feasibility of Cu/TiO2/AlN/Pt devices for multilevel non volatile ReRAM application.
      Graphical abstract image

      PubDate: 2017-12-27T06:12:27Z
  • Electrical and optical characterization of SiOxNy and SiO2 dielectric
           layers and rear surface passivation by using SiO2/SiOxNy stack layers with
           screen printed local Al-BSF for c-Si solar cells
    • Abstract: Publication date: January 2018
      Source:Current Applied Physics, Volume 18, Issue 1
      Author(s): Nagarajan Balaji, Huong Thi Thanh Nguyen, Cheolmin Park, Minkyu Ju, Jayapal Raja, Somenath Chatterjee, R. Jeyakumar, Junsin Yi
      In c-Si solar cells, surface recombination velocity increases as the wafer thickness decreases due to an increase in surface to volume ratio. For high efficiency, in addition to low surface recombination velocity at the rear side, a high internal reflection from the rear surface is also required. The SiOxNy film with low absorbance can act as rear surface reflector. In this study, industrially feasible SiO2/SiOxNy stack for rear surface passivation and screen printed local aluminium back surface field were used in the cell structure. A 3 nm thick oxide layer has resulted in low fixed oxide charge density of 1.58 × 1011 cm−2 without parasitic shunting. The oxide layer capped with SiOxNy layer led to surface recombination velocity of 155 cm/s after firing. Using single layer (SiO2) rear passivation, an efficiency of 18.13% has been obtained with Voc of 625 mV, Jsc of 36.4 mA/cm2 and fill factor of 78.7%. By using double layer (SiO2/SiOxNy stack) passivation at the rear side, an efficiency of 18.59% has been achieved with Voc of 632 mV, Jsc of 37.6 mA/cm2, and fill factor of 78.3%. An improved cell performance was obtained with SiO2/SiOxNy rear stack passivation and local BSF.

      PubDate: 2017-12-27T06:12:27Z
  • Uniaxial deformation of nanotwinned nanotubes in body-centered cubic
    • Abstract: Publication date: January 2018
      Source:Current Applied Physics, Volume 18, Issue 1
      Author(s): Shuozhi Xu, Saeed Zare Chavoshi
      We perform large-scale molecular dynamics simulations to delve into tensile and compressive loading of nanotubes containing {112} nanoscale twins in body-centered cubic tungsten, as a function of wall thickness, twin boundary spacing, and strain rate. Solid nanopillars without the interior hollow and/or nanotubes without the nanoscale twins are also investigated as references. Our findings demonstrate that both stress-strain response and deformation behavior of nanotwinned nanotubes and nanopillars exhibit a strong tension-compression asymmetry. The yielding of the nanotwinned nanotubes with thick walls is governed by dislocation nucleation from the twin boundary/surface intersections. With a small wall thickness, however, the failure of the nanotwinned nanotubes is dominated by crack formation and buckling under tensile and compressive loading, respectively. In addition, the strain rate effect, which is more pronounced in compressive loading than in tensile loading, increases with a decreasing twin boundary spacing.

      PubDate: 2017-12-27T06:12:27Z
  • Spin conductance in three-terminal rings subject to Rashba and Dresselhaus
           spin-orbit coupling
    • Abstract: Publication date: January 2018
      Source:Current Applied Physics, Volume 18, Issue 1
      Author(s): Han-Zhao Tang, Li-Xue Zhai, Jian-Jun Liu
      Based on the Green's function formalism, we investigated spin transport properties in one-dimensional three-terminal rings in the presence of the Rashba spin-orbit coupling (RSOC) and Dresselhaus spin-orbit coupling (DSOC). The conductance as a function of the Fermi energy shows typical resonance and antiresonance (conductance zero) characteristics in the absence of spin-orbit coupling (SOC). When one type of SOC (RSOC or DSOC) is introduced, the original conductance zeros are lifted, but new conductance zeros emerge. It is found that all the conductance zeros depend sensitively on the disorder, and the fluctuate weakens and smoothens the oscillations of the conductance. In the presence of both types of SOCs, the interplay between the RSOC and the DSOC opens a gap in the energy spectrum and breaks the cylindrical symmetry of the ring. Consequently, symmetrically coupled three-terminal rings show anisotropic conductances, which are robust against weak disorders.

      PubDate: 2017-12-27T06:12:27Z
  • Photothermally controlled 50 mA gating in VO2-based planar device
           using NIR laser diode
    • Abstract: Publication date: January 2018
      Source:Current Applied Physics, Volume 18, Issue 1
      Author(s): Jihoon Kim, Sun Jae Jeong, Bong-Jun Kim, Yong Wook Lee
      By utilizing a near infrared laser diode as an excitation light source, we demonstrated a photothermally controlled current gating of 50 mA in a two-terminal planar device based on a vanadium dioxide (VO2) thin film grown by a pulsed laser deposition method. The photothermally controlled on/off triggering of the device current was accomplished by controlling the output power of the laser beam that illuminated the VO2 film. The transient responses of photothermally triggered currents were analyzed when periodical laser pulses from the laser diode stimulated the VO2 device at a variety of pulse widths and repetition rates. A switching contrast between off-state and on-state currents was evaluated as ∼11905, and average rising and falling times were measured as ∼45 and ∼19 ms, respectively.

      PubDate: 2017-12-27T06:12:27Z
  • Performance of ring oscillators composed of gate-all-around FETs with
           varying numbers of nanowire channels using TCAD simulation
    • Abstract: Publication date: Available online 22 December 2017
      Source:Current Applied Physics
      Author(s): Sutae Kim, Minsuk Kim, Sola Woo, Hyungu Kang, Sangsig Kim
      In this paper, we investigate the performance of ring oscillators composed of gate-all-around (GAA) silicon nanowire (NW) field-effect transistors (FETs) with four different numbers of NW channels, for sub-10-nm logic applications. Our simulations reveal that ring oscillators with double, triple, and quadruple NW channels exhibit improvements of up to 50%, 85%, and 97%, respectively, in the oscillation frequencies (f osc ), compared to a ring oscillator with a single NW channel, due to the large drive current, in spite of the increased intrinsic capacitance of a given device. Moreover, our work shows that the f osc improvement ratio of the ring oscillators becomes saturated with triple NW channels with additional load capacitances of 0.1 fF and 0.01 fF, which are similar to, or less than the intrinsic device capacitance (∼0.1 fF). Thus, our study provides an insight for determining the capacitive load and optimal number of NW channels, for device development and circuit design of GAA NW FETs.

      PubDate: 2017-12-27T06:12:27Z
  • Resonant Raman scattering from CdTe/ZnTe self-assembled quantum dot
    • Abstract: Publication date: Available online 21 December 2017
      Source:Current Applied Physics
      Author(s): Seulki Baik, Hong Seok Lee, Heesuk Rho
      We report resonant Raman scattering results of CdTe/ZnTe self-assembled quantum dot (QD) structures. Photoluminescence spectra reveal that the band gap energies of the CdTe QDs decrease with the increase of CdTe thickness from 2.0 to 3.5 monolayers, which indicates that the size of the QDs increases. When the CdTe/ZnTe QD structures are excited by non-resonant excitation, a longitudinal optical (LO) phonon response from the ZnTe barrier material is observed at 206 cm−1. In contrast, when the CdTe/ZnTe QD structures are resonantly excited near the band gap energy of the QDs, additional phonon modes emerge at 167 and 200 cm−1, while the ZnTe LO phonon response completely disappears. The 167 cm−1 mode corresponds to the LO phonon of the CdTe QDs. A spatially resolved Raman scattering from the cleaved edge of the QD sample reveals that the 200 cm−1 mode is strongly localized at the interface between the CdTe QDs and ZnTe cap layer. This phonon mode is attributed to the interface optical (IO) phonon. The analytically calculated value of the IO phonon energy using a dielectric continuum approach, assuming a spherical dot boundary, agrees well with the experimental value.

      PubDate: 2017-12-27T06:12:27Z
  • Zero-field cooled exchange bias and magnetization reversal in
    • Abstract: Publication date: Available online 15 December 2017
      Source:Current Applied Physics
      Author(s): L. Xie, H.G. Zhang
      The polycrystalline sample La1.5Sr0.5Co0.4Fe0.6MnO6 (LSCFMO) was prepared by sol-gel method and its magnetic properties were studied. The interesting magnetization reversal phenomenon and the zero-field cooled exchange bias (ZEB) effect were simultaneously observed in LSCFMO. ZEB effect can exist in a wider temperature range (0–200 K) compared with La1.5Sr0.5CoMnO6 (0–10 K), which is very important in the potential applications. A schematic diagram based on the coupling between the Fe3+ spins, Mn3+ spins and Co2+ or Co3+ spins is used to understand the ZEB and the reversal behaviors. Due to the doping of 60% Fe ion, the magnetic microstructure of LSCMFO is more complex than that of LSCMO, resulting in the meta-stable spin structure and more interesting magnetic phenomenon.

      PubDate: 2017-12-27T06:12:27Z
  • Fabrication and applications of ultraflexible nanostructures using
           dielectric heating-assisted nanoimprint on PVC films
    • Abstract: Publication date: Available online 7 November 2017
      Source:Current Applied Physics
      Author(s): Tsung-Yeh Wu, Po-Cheng Tsai, Shu-Cheng Lo, Yi-Ru Li, Kuang-Li Lee, Sen-Yeu Yang, Pei-Kuen Wei
      We developed dielectric heating-assisted nanoimprint method for rapid fabrication of ultraflexible nanostructures. Using spin-coating polyvinyl-chloride (PVC) film on the glass slide, the dielectric heating on PVC film helped the pattern transfer from the mold to PVC film in few seconds. Various kinds of nanostructures were successfully made on PVC films with about 20-μm thickness. We demonstrated the applications of ultraflexible metallic nanostructures for bending measurement using surface plasmon resonance (SPR) and surface enhanced Raman scattering (SERS) on the curved surfaces. For measuring bending angles using SPR on capped nanowire arrays, the minimum detection angle was 2.4 × 10−3 degree under 0.02 nm wavelength resolution. For SERS measurement, the nanorod arrays on a curved substrate can increase SERS signals for two times as compared to planar SERS substrate.

      PubDate: 2017-11-08T14:24:58Z
  • Facilitating epitaxial growth of ZnO films on patterned GaN layers: A
           solution-concentration-induced successive lateral growth mechanism
    • Abstract: Publication date: Available online 7 November 2017
      Source:Current Applied Physics
      Author(s): Rong-Ming Ko, Yan-Ru Lin, Ching-Yi Chen, Pai-Feng Tseng, Shui-Jinn Wang
      The hydrothermal epitaxy of ZnO films on a patterned GaN layer with a honeycomb etching hole array is demonstrated. Through m-planes of the GaN layer exposed on the vertical walls of the etching holes, highly crystalline ZnO films via multiple lateral growth stages can be realized. It is found that higher concentrations of zinc nitrate hexahydrate (ZNH) and hexamethylenetetramine (HMT) in hydrothermal solution yield a larger number of ZnO molecules to speed up ZnO growth during the initial stage of hydrothermal growth, also create secondary crystals and initialize further lateral growth stages to bridge neighboring ZnO prisms after smooth surfaces formed on the m-plane of a ZnO prism. A successive lateral growth mechanism that strongly depends on ZNH and HMT concentrations in the hydrothermal solution is proposed and discussed.
      Graphical abstract image

      PubDate: 2017-11-08T14:24:58Z
  • DFT study of the adsorption of 2, 3, 7, 8-tetrachlorodibenzofuran (TCDF)
           on vacancy-defected graphene doped with Mn and Fe
    • Abstract: Publication date: Available online 2 November 2017
      Source:Current Applied Physics
      Author(s): Qingxiao Zhou, Yongliang Yong, Weiwei Ju, Xiangying Su, Xiaohong Li, Chaoyang Wang, Zhibing Fu
      Dioxins are highly toxic to humans and environment, and developing the effective methods to control and detect the organic pollutant is particular important. Here we performed a density functional theory (DFT) study on the adsorption of 2, 3, 7, 8-tetrachlorodibenzofuran (TCDF) molecules on the modified graphene substrates. The results indicated that the introducing of vacancy-defect and dopants (Mn and Fe) significantly improves the sensitivity toward TCDF molecules. The impurity played a crucial role for interacting with TCDF molecules. Furthermore, the adsorption of TCDF induced band-gap open in defected graphene substrates, which could be seen as electric signal to detect TCDF pollutant. The present study is expected to be useful to explore effective materials to detect and remove dioxin pollutants based on graphene.

      PubDate: 2017-11-08T14:24:58Z
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