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  Subjects -> ENGINEERING (Total: 2417 journals)
    - CHEMICAL ENGINEERING (207 journals)
    - CIVIL ENGINEERING (202 journals)
    - ELECTRICAL ENGINEERING (111 journals)
    - ENGINEERING (1267 journals)
    - ENGINEERING MECHANICS AND MATERIALS (400 journals)
    - HYDRAULIC ENGINEERING (56 journals)
    - INDUSTRIAL ENGINEERING (76 journals)
    - MECHANICAL ENGINEERING (98 journals)

ENGINEERING (1267 journals)                  1 2 3 4 5 6 7 | Last

Showing 1 - 200 of 1205 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 8)
3D Research     Hybrid Journal   (Followers: 21)
AAPG Bulletin     Hybrid Journal   (Followers: 8)
AASRI Procedia     Open Access   (Followers: 14)
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: 273)
Acta Geotechnica     Hybrid Journal   (Followers: 7)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 7)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 3)
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: 7)
Advanced Journal of Graduate Research     Open Access  
Advanced Science     Open Access   (Followers: 5)
Advanced Science Focus     Free   (Followers: 5)
Advanced Science Letters     Full-text available via subscription   (Followers: 10)
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: 5)
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: 17)
Advances in Fuzzy Systems     Open Access   (Followers: 5)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 13)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 21)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 22)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 9)
Advances in Natural Sciences: Nanoscience and Nanotechnology     Open Access   (Followers: 29)
Advances in Operations Research     Open Access   (Followers: 12)
Advances in OptoElectronics     Open Access   (Followers: 6)
Advances in Physics Theories and Applications     Open Access   (Followers: 13)
Advances in Polymer Science     Hybrid Journal   (Followers: 43)
Advances in Porous Media     Full-text available via subscription   (Followers: 5)
Advances in Remote Sensing     Open Access   (Followers: 44)
Advances in Science and Research (ASR)     Open Access   (Followers: 6)
Aerobiologia     Hybrid Journal   (Followers: 3)
African Journal of Science, Technology, Innovation and Development     Hybrid Journal   (Followers: 6)
AIChE Journal     Hybrid Journal   (Followers: 35)
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: 26)
American Journal of Engineering and Applied Sciences     Open Access   (Followers: 10)
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: 24)
Analele Universitatii Ovidius Constanta - Seria Chimie     Open Access  
Annals of Combinatorics     Hybrid Journal   (Followers: 4)
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)
Antarctic Science     Hybrid Journal   (Followers: 1)
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: 6)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 11)
Applied Magnetic Resonance     Hybrid Journal   (Followers: 4)
Applied Nanoscience     Open Access   (Followers: 8)
Applied Network Science     Open Access   (Followers: 3)
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Physics Research     Open Access   (Followers: 5)
Applied Sciences     Open Access   (Followers: 3)
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: 5)
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: 28)
Beni-Suef University Journal of Basic and Applied Sciences     Open Access   (Followers: 4)
BER : Manufacturing Survey : Full Survey     Full-text available via subscription   (Followers: 1)
BER : Motor Trade Survey     Full-text available via subscription  
BER : Retail Sector Survey     Full-text available via subscription   (Followers: 1)
BER : Retail Survey : Full Survey     Full-text available via subscription   (Followers: 1)
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)
Beyond : Undergraduate Research Journal     Open Access  
Bhakti Persada : Jurnal Aplikasi IPTEKS     Open Access  
Bharatiya Vaigyanik evam Audyogik Anusandhan Patrika (BVAAP)     Open Access   (Followers: 1)
Bilge International Journal of Science and Technology Research     Open Access  
Biofuels Engineering     Open Access   (Followers: 1)
Biointerphases     Open Access   (Followers: 1)
Biomaterials Science     Full-text available via subscription   (Followers: 11)
Biomedical Engineering     Hybrid Journal   (Followers: 15)
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: 21)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 37)
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   (Followers: 1)
Biomicrofluidics     Open Access   (Followers: 4)
BioNanoMaterials     Hybrid Journal   (Followers: 2)
Biotechnology Progress     Hybrid Journal   (Followers: 39)
Bitlis Eren University Journal of Science and Technology     Open Access  
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: 12)
Bulletin of Canadian Petroleum Geology     Full-text available via subscription   (Followers: 13)
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   (Followers: 2)
Canadian Geotechnical Journal     Hybrid Journal   (Followers: 31)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 42)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 6)
Case Studies in Thermal Engineering     Open Access   (Followers: 5)
Catalysis Communications     Hybrid Journal   (Followers: 6)
Catalysis Letters     Hybrid Journal   (Followers: 2)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 7)
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  
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: 3)
CienciaUAT     Open Access   (Followers: 1)
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: 13)
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: 1)
Clinical Science     Full-text available via subscription   (Followers: 9)
Coal Science and Technology     Full-text available via subscription   (Followers: 3)
Coastal Engineering     Hybrid Journal   (Followers: 11)
Coastal Engineering Journal     Hybrid Journal   (Followers: 6)
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: 14)
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: 28)
Composite Interfaces     Hybrid Journal   (Followers: 7)
Composite Structures     Hybrid Journal   (Followers: 277)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 209)
Composites Part B : Engineering     Hybrid Journal   (Followers: 249)
Composites Science and Technology     Hybrid Journal   (Followers: 194)
Comptes Rendus Mécanique     Full-text available via subscription   (Followers: 2)
Computation     Open Access   (Followers: 1)
Computational Geosciences     Hybrid Journal   (Followers: 16)
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: 31)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 8)
Computers and Electronics in Agriculture     Hybrid Journal   (Followers: 5)
Computers and Geotechnics     Hybrid Journal   (Followers: 11)
Computing and Visualization in Science     Hybrid Journal   (Followers: 7)
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)

        1 2 3 4 5 6 7 | Last

Journal Cover
Current Applied Physics
Journal Prestige (SJR): 0.647
Citation Impact (citeScore): 2
Number of Followers: 4  
 
  Full-text available via subscription Subscription journal
ISSN (Print) 1567-1739
Published by Elsevier Homepage  [3163 journals]
  • Waveguiding behavior of VLS-grown one-dimensional Ga-doped In2O3
           nanostructures
    • Authors: Jesús Alberto Ramos Ramón; U. Pal; David Maestre; Ana Cremades
      Pages: 785 - 792
      Abstract: Publication date: Available online 12 April 2018
      Source:Current Applied Physics
      Author(s): Jesús Alberto Ramos Ramón, U. Pal, David Maestre, Ana Cremades
      Highly crystalline undoped and Ga-doped indium oxide nanorods with square-shaped faceted morphology were fabricated through the vapor-liquid-solid process at moderate temperature. Effects of Ga incorporation on the growth rate, morphology, and crystallinity of the nanostructures were evaluated by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. Defect structure and waveguiding behavior of the 1-D In2O3 nanostructures have been studied using microRaman and micro photoluminescence spectroscopies. The appearance of several resonant modes superposed over the broad room temperature micro-photoluminescence spectra of the nanostructures demonstrates their waveguiding behaviors. While the pristine or undoped In2O3 nanostructures of 20–150 nm widths revealed Fabry-Pérot resonance modes, the Ga-incorporated nanostructures of 20–100 nm width revealed whispering gallery modes due to their smaller widths. The quality factor (Q) of the resonators was estimated to be about 20.86 and 188.79 for the pristine and Ga-incorporated nanostructures, respectively, indicating a huge enhancement due to Ga incorporation. The increment in the Q factor on Ga incorporation in In2O3 nanorods opens up the possibility of their utilization for the development of new optical transmitters and resonators, and fabrication of nanoscopic lasing devices.
      Graphical abstract image

      PubDate: 2018-04-15T10:39:07Z
      DOI: 10.1016/j.cap.2018.04.009
      Issue No: Vol. 18, No. 7 (2018)
       
  • Enhanced UV/blue fluorescent sensing using metal-dielectric-metal aperture
           nanoantenna arrays
    • Authors: Quang Minh Ngo; Ying-Lung D. Ho; Jon R. Pugh; Andrei Sarua; Martin J. Cryan
      Pages: 793 - 798
      Abstract: Publication date: Available online 11 April 2018
      Source:Current Applied Physics
      Author(s): Quang Minh Ngo, Ying-Lung D. Ho, Jon R. Pugh, Andrei Sarua, Martin J. Cryan
      Subwavelength aperture antenna arrays are designed and fabricated for potential applications in fluorescence sensing in the near UV/blue range. They are designed using finite-difference time-domain (FDTD) simulation, fabricated using focused ion beam etching and characterised using angular Fourier spectroscopy. The aperture arrays are formed in the top layer of an aluminum-silica-aluminum trilayer and produce a maximum simulated field intensity enhancement of 5.8 times at 406 nm and highly directive emission with a beamwidth of 8.3 deg. The normal incidence reflection response has been measured and shows reasonable agreement with modelled results. In addition, to investigate higher field intensity enhancements, bowtie aperture arrays are simulated and the influence of parameters such as dielectric gap, position of dipole source, and aperture shape and size are discussed and show enhancements up to 67 times are possible.
      Graphical abstract image

      PubDate: 2018-04-15T10:39:07Z
      DOI: 10.1016/j.cap.2018.04.007
      Issue No: Vol. 18, No. 7 (2018)
       
  • First-principles study on the Poisson's ratio of transition-metal
           dichalcogenides
    • Authors: Yongmin Yoo; Jin-Hoon Yang; Joo-Hyoung Lee
      Pages: 799 - 802
      Abstract: Publication date: Available online 6 April 2018
      Source:Current Applied Physics
      Author(s): Yongmin Yoo, Jin-Hoon Yang, Joo-Hyoung Lee
      In this study, we investigate the Poisson's ratio of transition-metal dichalcogenides (TMDCs) with a chemical formula of MX2, where M = Mo, W and X = S, Se, respectively, from first-principles. Through density functional theory calculations, it is demonstrated that the Poisson's ratio of MX2 exhibits not only a substantial difference between the planar and vertical values but also a systematic dependence on the chalcogen species. Among the TMDCs, MoS2 displays the strongest anisotropy, which entails a distinctive contracting response under a planar strain. We find that such pronounced anisotropy in the Poisson's ratio of the TMDCs originates from the different filling of the in- (p x , p y , d xy , and d x 2 − y 2 ) and out-of-plane (p z , d yz , d zx , and d z 2 ) electronic orbitals depending on the transition-metal elements. These findings shed a new light on the elastic properties of TMDCs which continue to be interesting and show intriguing phenomena.

      PubDate: 2018-04-15T10:39:07Z
      DOI: 10.1016/j.cap.2018.03.018
      Issue No: Vol. 18, No. 7 (2018)
       
  • An approach to MgCl2 activation on CdSe thin films for solar cells
    • Authors: S.L. Patel; A. Purohit; S. Chander; M.D. Kannan; M.S. Dhaka
      Pages: 803 - 809
      Abstract: Publication date: Available online 11 April 2018
      Source:Current Applied Physics
      Author(s): S.L. Patel, A. Purohit, S. Chander, M.D. Kannan, M.S. Dhaka
      The energy demand of the world is rapidly increasing and to cater this, there is a need to explore new renewable energy resources. CdSe thin film solar cells may be promising alternative to the CdTe solar cells which is extensively studied and used solar cell technology. The pre/post deposition chlorine based treatments (viz. CdCl2, MgCl2, NH4Cl) are the important steps to enhance the performance of Cd-based thin film solar cells. Therefore, a study on MgCl2 activation treatment to CdSe thin films for solar cell applications as absorber layer is undertaken. Different physical properties of e-beam evaporated CdSe films (thickness 550 nm) grown on glass and ITO substrates are investigated and found to be strongly dependent on the post-chlorine treatment. The films have cubic zinc-blende structure and phase transformation from cubic (111) to hexagonal (002) is achieved with the MgCl2 treatment while the optical band gap is reduced. I-V characteristics reveal the linear relation between voltage and current as well as the surface roughness is varied with treatment and improved homogeneity. The deposition of CdSe thin films is confirmed by elemental analysis where Cd and Se were found to be rich with treatment. The investigated results suggest that CdSe thin films treated by MgCl2 and annealed at 320 °C may be a viable alternative absorber layer to the Cd-based solar cells.
      Graphical abstract image

      PubDate: 2018-04-15T10:39:07Z
      DOI: 10.1016/j.cap.2018.04.008
      Issue No: Vol. 18, No. 7 (2018)
       
  • Tunable optical vortex arrays using spontaneous periodic pattern formation
           in nematic liquid crystal cells
    • Authors: L.K. Migara; Cheon-Myeong Lee; Keumcheol Kwak; Heesu Lee; Jang-Kun Song
      Pages: 819 - 823
      Abstract: Publication date: Available online 9 April 2018
      Source:Current Applied Physics
      Author(s): L.K. Migara, Cheon-Myeong Lee, Keumcheol Kwak, Heesu Lee, Jang-Kun Song
      Controllable liquid crystal (LC) defects can provide an effective approach to creating tunable optical vortices. We develop a method to create tunable matter vortex arrays in an LC cell, in which +1 and −1 defects are periodically arranged in a square grid lattice. Spontaneous formation of the periodic defect array is achieved using a spontaneous standing pressure wave without using any patterned electrode or patterned alignment layer. The +1 and −1 defects in the array can induce optical vortices with opposite handedness, and the matter vortex array produces a periodic optical vortex array with orbital angular momenta of −2ℏ and +2ℏ in the same grid lattice. Because the pitch of the grid can be controlled, the method can provide a useful pathway to producing tunable optical vortex arrays for various applications such as advanced optical communication and quantum computation.

      PubDate: 2018-04-15T10:39:07Z
      DOI: 10.1016/j.cap.2018.04.005
      Issue No: Vol. 18, No. 7 (2018)
       
  • Highly directional waveguide grating antenna for optical phased array
    • Authors: Kyunghun Han; Victor Yurlov; Nan Ei Yu
      Pages: 824 - 828
      Abstract: Publication date: Available online 6 April 2018
      Source:Current Applied Physics
      Author(s): Kyunghun Han, Victor Yurlov, Nan Ei Yu
      A highly directional waveguide grating antenna by patterning top cladding has been proposed. Spatial separation of the grating structure from the waveguide reduces the strength of perturbation to achieve a millimeter-scale emission. The optimized grating structure offers above 70% directionality with 800 nm waveguide width. The vertical field-of-view of 15° is achieved with 100 nm wavelength bandwidth. Thanks to the its simple structure and large critical dimension, the proposed structure is suitable for manufacturing in CMOS foundries with DUV lithography.

      PubDate: 2018-04-15T10:39:07Z
      DOI: 10.1016/j.cap.2018.04.004
      Issue No: Vol. 18, No. 7 (2018)
       
  • Exciton-phonon coupling channels in a ‘strain-free’ GaAs droplet
           epitaxy single quantum dot
    • Authors: Song-ee Lee; Inah Yeo; Min Kyung Jo; Young Woo Jeong; Tae Geun Kim; Jong Su Kim; Kyung Soo Yi; Il Ki Han; Jin Dong Song
      Pages: 829 - 833
      Abstract: Publication date: Available online 9 April 2018
      Source:Current Applied Physics
      Author(s): Song-ee Lee, Inah Yeo, Min Kyung Jo, Young Woo Jeong, Tae Geun Kim, Jong Su Kim, Kyung Soo Yi, Il Ki Han, Jin Dong Song
      We examine the temperature-dependent excitonic transition energy shift of strain-free GaAs droplet epitaxy (DE) quantum dots (QDs). Interestingly the statistical investigation of QD optical properties enables us to observe three distinct temperature dispersions for four series of DE QDs. We present comparative analyses of the exciton-phonon coupling mechanisms employing various empirical to multi-oscillator models associated with each QD-specific phonon dispersion spectrum. The systematic investigation of such QD exciton-phonon coupling is crucial for fine control of local defects in engineered quantum dot single-photon sources.

      PubDate: 2018-04-15T10:39:07Z
      DOI: 10.1016/j.cap.2018.04.003
      Issue No: Vol. 18, No. 7 (2018)
       
  • Specific contact resistance of IGZO thin film transistors with metallic
           and transparent conductive oxides electrodes and XPS study of the
           contact/semiconductor interfaces
    • Authors: M.E. Rivas-Aguilar; N. Hernandez-Como; G. Gutierrez-Heredia; A. Sánchez-Martínez; M. Mireles Ramirez; I. Mejia; M.A. Quevedo-López
      Pages: 834 - 842
      Abstract: Publication date: Available online 7 April 2018
      Source:Current Applied Physics
      Author(s): M.E. Rivas-Aguilar, N. Hernandez-Como, G. Gutierrez-Heredia, A. Sánchez-Martínez, M. Mireles Ramirez, I. Mejia, M.A. Quevedo-López
      In this work, the specific contact resistance (ρc) between amorphous indium-gallium-zinc-oxide (IGZO) semiconductor and different contact electrodes was obtained from thin film transistors (TFTs). Ti/Au (10/100 nm), aluminum doped zinc oxide (AZO, 100 nm) and indium tin oxide (ITO, 100 nm) were used as source/drain electrodes to fabricate IGZO TFTs. Chemical states of the contacts/semiconductor interfaces were examined by depth profile X-ray photoelectron spectroscopy (XPS) analysis to explain the origin of the differences on specific contact resistance. The lowest ρc achieved using Ti/Au was related to the formation of a TiOx interlayer due to oxygen atoms diffusing out from the semiconductor under layer, increasing the carrier concentration of IGZO at the interface and lowering the ρc. On the contrary, no interfacial reactions were observed between IGZO and AZO or ITO source/drain. However, IGZO resistivity increased with ITO contacts likely due to oxygen vacancies filling during ITO deposition. This fact seems to be the origin of the high contact resistance between IGZO and ITO, compared to IGZO-AZO and IGZO-Ti/Au interfaces.

      PubDate: 2018-04-15T10:39:07Z
      DOI: 10.1016/j.cap.2018.04.002
      Issue No: Vol. 18, No. 7 (2018)
       
  • Electrical metal contacts to atomically thin 2H-phase MoTe2 grown by
           metal–organic chemical vapor deposition
    • Authors: TaeWan Kim; DaeHwa Joung; Jonghoo Park
      Pages: 843 - 846
      Abstract: Publication date: Available online 6 April 2018
      Source:Current Applied Physics
      Author(s): TaeWan Kim, DaeHwa Joung, Jonghoo Park
      We grow atomically thin molybdenum ditelluride (MoTe2) films on a SiO2/Si substrate by means of metal–organic chemical vapor deposition (MOCVD). Our Raman spectroscopy measurements reveal the formation of 2H-phase MoTe2 films. Further, transmission electron microscopy and X-ray photoelectron spectroscopy studies indicate a three-atomic-layer structure and the surface element composition of MoTe2 films. In this study, we mainly focus on the influence of metal contacts attached to the films on their electrical performance. We fabricate 2H-phase-MoTe2-based field-effect transistors (FETs) with various metal contacts such as titanium/gold, nickel and palladium, which present p-type semiconductor properties. We also examine the influence of the work functions of the contact metals on the electrical properties of three-atomic-layer-MoTe2-based FET devices. For a p-type MoTe2 semiconductor, higher work functions of the contact metals afford narrower Schottky barrier heights (SBHs) and eventually highly efficient carrier injection through the contacts.

      PubDate: 2018-04-15T10:39:07Z
      DOI: 10.1016/j.cap.2018.04.001
      Issue No: Vol. 18, No. 7 (2018)
       
  • Damping and transformation behaviors of Ti50(Pd50−xCrx) shape memory
           alloys with x ranging from 4.0 to 5.0
    • Authors: Deqing Xue; Ruihao Yuan; Dezhen Xue; Yumei Zhou; Guojun Zhang; Xiangdong Ding; Jun Sun
      Pages: 847 - 852
      Abstract: Publication date: Available online 3 April 2018
      Source:Current Applied Physics
      Author(s): Deqing Xue, Ruihao Yuan, Dezhen Xue, Yumei Zhou, Guojun Zhang, Xiangdong Ding, Jun Sun
      The damping and transformation behaviors of Ti50(Pd50−x Cr x ) shape memory alloys with x ranging from 4.0 to 5.0 are systematically investigated. The damping capacity (Q−1) at the martensitic transformation is found to be inversely proportional to the square root of frequency, i.e., Q−1∝ω −0.5. A relaxation peak or shoulder is observed slightly below the martensitic transformation damping peak for compositions within the compositional crossover region (4.5 ⩽ x ⩽ 4.8). Furthermore, the damping capacity at the martensitic transformation is smaller within the compositional crossover region (4.5 ⩽ x ⩽ 4.8), compared with that of compositions at both sides ( x = 4.0 and x = 5.0 ). These observations can be ascribed to the hysteretic motion of interfaces between different phases near the compositional crossover region.

      PubDate: 2018-04-15T10:39:07Z
      DOI: 10.1016/j.cap.2018.03.025
      Issue No: Vol. 18, No. 7 (2018)
       
  • Theoretical probe on modified organic dyes for high-performance
           dye-sensitised solar cell
    • Abstract: Publication date: September 2018
      Source:Current Applied Physics, Volume 18, Issue 9
      Author(s): S. Krishnan, K. Senthilkumar
      We have proposed newly designed organic sensitizers, which could potentially be the best performing organic dyes for Dye Sensitised Solar Cell applications (DSSC). The designed sensitizers are derivatives of “Triphenylamine (TPA) - Tetrathienoacene (TTA) - Thiophene (T) - cyanoacrylic acid (A)” (TPA-TTAR-T-A) sensitizer. Our conclusions were based on calculations performed using Density Functional Theory (DFT) and Time Dependent Density Functional Theory (TD-DFT) methods, on various theoretical parameters of sensitizers that are pertinent to the Power Conversion Efficiency (PCE) of the solar cell. We strategically incorporated substitutions on the spacer located between the π - bridge and the anchoring group, where the thiophene was inserted in previous study. We found that strengthening the electron withdrawing ability around thiophene spacer by fluorination and cyano substitution, and replacement of thiophene spacer with fluorinated and cyano substituted benzodithiophene complexes results in improved opto-electronic properties of the sensitizers. Thereby, we identified six new derivatives and for each derivative we have studied the parameters concerning short circuit current (Jsc), such as molecular geometry, absorption spectrum, frontier molecular orbital patterns, electronic energy levels and excited state life time. Also, we have analysed the intramolecular charge transport characteristics of the designed dyes. By considering the overall computed parameters we were able to sort out two new sensitizers TPA-TTAR-2FT-A and TPA-TTAR-2F2CNBDT-A that delivered the needed characteristics and thereby brings in confidence that these sensitizers could challenge TPA-TTA-T-A as the best performing organic sensitizer.
      Graphical abstract image

      PubDate: 2018-06-18T16:37:23Z
       
  • Andreev tunneling and Josephson current in light irradiated graphene
    • Abstract: Publication date: September 2018
      Source:Current Applied Physics, Volume 18, Issue 9
      Author(s): Debabrata Sinha, Satyaki Kar
      We investigate the Andreev tunneling and Josephson current in graphene irradiated with high-frequency linearly polarized light. The corresponding stroboscopic dynamics can be solved using Floquet mechanism which results in an effective stationary theory to the problem exhibiting an anisotropic Dirac spectrum and modified pseudospin-momentum locking. When applied to an irradiated normal graphene - superconductor (NS) interface, such analysis reveal Andreev reflection (AR) to become an oscillatory function of the optical strength. Specifically we find that, by varying the polarization direction we can both suppress AR considerably or cause the Andreev transport to remain maximum at sub-gap excitation energies even in the presence of Fermi level mismatch. Furthermore, we study the optical effect on the Andreev bound states (ABS) within a short normal-graphene sheet, sandwiched between two s-wave superconductors. It shows redistribution of the low energy regime in the ABS spectrum, which in turn, has major effect in shaping the Josephson super-current. Subjected to efficient tuning, such current can be sufficiently altered even at the charge neutrality point. Our observations provide useful feedback in regulating the quantum transport in Dirac-like systems, achieved via controlled off-resonant optical irradiation on them.

      PubDate: 2018-06-18T16:37:23Z
       
  • The effects of oxygen vacancies on the electrical properties of W, Ti
           doped CaBi2Nb2O9 piezoceramics
    • Abstract: Publication date: Available online 15 June 2018
      Source:Current Applied Physics
      Author(s): Xinghe Xing, Feng Cao, Zhihang Peng, Yang Xiang
      Different type doped CaBi2Nb2O9 (CBN) ceramics were prepared by a conventional solid state sintering method. The number of oxygen vacancies were decreased or increased by the introduction of W6+ and Ti4+ doping in CBN ceramics. The influence of W6+, Ti4+ and W6+/Ti4+ dopants on the microstructures and electrical properties of CBN-based ceramics was investigated. The voids and spherical morphology in the SEM image of W, Ti co-doped ceramics indicate that W, Ti co-doping could change the microstructure of CBN-based ceramics. Impedance analysis results show that the electrical properties of CBN-based ceramics have a close relationship with the number of oxygen vacancies. W doping and W, Ti co-doping decrease the oxygen vacancies, as a result, the resistance and piezoelectric properties were increased and the frequency dispersion of dielectric properties were restrained.

      PubDate: 2018-06-18T16:37:23Z
       
  • Modeling of the initial stages of the formation of heterogeneous plasma
           flows in the electric explosion of conductors
    • Abstract: Publication date: Available online 15 June 2018
      Source:Current Applied Physics
      Author(s): Vladimir Sarychev, Sergey Nevskii, Sergey Konovalov, Alexei Granovskii
      The experimental and theoretical studies on scattering of electric explosion products in the end-type plasma accelerator are carried out. Using the method of high-speed imaging (106 shots per second), it is revealed that there are three zones in a heterogeneous plasma flow. Zone 1 is a plasma focus, in Zone 2 there is a 90° turn of a flow, whereas a plasma flow is parallel to the dielectric disk in Zone 3. Following the concepts of plasma scattering when exposed to magnetic and gas-dynamic pressure, a mathematical model is proposed and provides an adequate explanation of plasma motion in Zone 3. It comprises equations of laws of mass and conservation of momentum, as well as the first and second Kirchhoff's laws. The outcomes of modeling are in compliance with the experimental data. A numerical single-fluid magnetohydrodynamic model is developed for general description of formation and evolution of a plasma flow. It is based on Navier-Stokes and Maxwell's equations. The obtained patterns of plasma current distribution agree satisfactory with the results of high-speed imaging. They point at a jet in the central part of the electrode, which splits out with the distance from its surface.

      PubDate: 2018-06-18T16:37:23Z
       
  • Pentacene as a hole transport material for high performance planar
           perovskite solar cells
    • Abstract: Publication date: Available online 8 June 2018
      Source:Current Applied Physics
      Author(s): Xiude Yang, Gang Wang, Debei Liu, Yanqing Yao, Guangdong Zhou, Ping Li, Bo Wu, Xi Rao, Qunliang Song
      A cost-effective and efficient organic semiconductor pentacene was developed as a hole transport layer (HTL) material to replace classical PEDOT:PSS for planar perovskite solar cells (PSCs). As expected, the pentacene based device exhibits power conversion efficiency (PCE) of 15.90% (Jsc of 19.44 mA/cm2, Voc of 1.07 V, and FF of 77%), comparable to the PEDOT:PSS based device (PCE of 15.65%, Jsc of 18.78 mA/cm2, Voc of 1.07 V, and FF of 77%) under the same experimental conditions. The excellent performance of vacuum deposited pentacene is mainly attributed to the high efficient charge extraction and transfer in device due to the high-quality perovskite film grown on the top of pentacene substrate and a favorable energy-level alignment together with a desired downward band bending formed at the perovskite/pentacene interface. Our research has confirmed that pentacene could be served as a promising HTL material to achieve effective and potentially economical planar type PSCs.
      Graphical abstract image

      PubDate: 2018-06-09T15:57:44Z
       
  • High-performance amorphous indium gallium zinc oxide thin-film transistors
           with sol-gel processed gate dielectric and channel layer fabricated using
           microwave irradiation
    • Abstract: Publication date: Available online 4 June 2018
      Source:Current Applied Physics
      Author(s): Min-Soo Kang, Won-Ju Cho
      In this study, we fabricated high-performance a-IGZO TFTs by forming Al2O3 and a-IGZO thin films for gate insulator and active channel layer, respectively, using a sol-gel process. MWI for low thermal budget process was used to condensate Al2O3 and a-IGZO films, which was compared with the CTA. It is found that the MWI is superior process to the conventional method in terms of precursor and solvent decomposition and has proven to be more effective for eliminating residual organic contaminants. In addition, the MWI-treated Al2O3 and IGZO films have smoother surfaces, higher visible light transmittance, lower carbon contamination and impurities than the CTA-treated films. We have demonstrated that a-IGZO TFTs with sol-gel solution-processed Al2O3 gate insulator and a-IGZO channel layer can achieve a field effect mobility of 69.2 cm2/V·s, a subthreshold swing of 86.2 mV/decade and a large on/off current ratio of 1.48 × 108, by the MWI process even at temperatures below 200 °C. In addition, the MWI-treated a-IGZO TFTs have excellent resistance to electron trapping and good stability to positive and negative gate-bias stress. Therefore, the sol-gel processed a-IGZO TFTs with Al2O3 gate oxide and the MWI treatment with a low thermal budget are promising for emerging transparent flat panel displays applications.

      PubDate: 2018-06-06T15:48:31Z
       
  • Electronic and magnetic properties of the [4Fe-4S] iron-sulfur clusters
           encapsulated in a single-walled semiconducting carbon nanotube
    • Abstract: Publication date: September 2018
      Source:Current Applied Physics, Volume 18, Issue 9
      Author(s): Małgorzata Wawrzyniak-Adamczewska
      The electronic and magnetic properties of the charge neutral iron-sulfur clusters, [4Fe-4S], encapsulated in a semiconducting single-walled carbon nanotube, CNT(17,0), are examined within the density functional theory approach. We verified that for the isolated cluster, due to exchange coupling between the electron spins on iron ions, the antiferromagnetic ground state with the total spin S = 0 is formed. The encapsulation provides the significant charge transfer from the carbon nanotube to the embedded molecule. In consequence, a shift of the molecular levels with broadening of the HOMO-LUMO gap is observed, and the significant p-doping of the surrounding nanotube with narrowing its energy band gap occurs. This transferred charge is found to be localized on the iron centers and contributes to the reduction of the value of the magnetic moments on the iron centers. We find that, the antiferromagnetic arrangement of the magnetic moments on the molecule is preserved after encapsulation and no net magnetic moment is induced on the carbon nanotube. We also ascertained that the considered hybrid system is of the p-degenerated semiconducting type.

      PubDate: 2018-06-03T15:37:56Z
       
  • ZnO nanoparticles dispersed PVA–PVP blend matrix based high performance
           flexible nanodielectrics for multifunctional microelectronic devices
    • Abstract: Publication date: September 2018
      Source:Current Applied Physics, Volume 18, Issue 9
      Author(s): Shobhna Choudhary, R.J. Sengwa
      Polymer nanocomposite (PNC) films based on the blend matrix of poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP) (50/50 wt%) incorporated with zinc oxide (ZnO) nanoparticles (i.e., (PVA–PVP)–x wt% ZnO; x = 0, 1, 3 and 5) were prepared by solution-cast method. The behaviour of polymer-polymer and polymer-nanoparticle interactions in the PNC films was ascertained by employing X-ray diffraction, energy dispersive X-ray, and Fourier transform infra-red spectroscopies. Scanning electron microscopy and atomic force microscopy were performed for the morphological characterization, whereas the thermal and optical properties of the PNC films were investigated by using differential scanning calorimetry and ultraviolet–visible spectroscopy, respectively. The dielectric and electrical behaviour of these PNC materials were determined by employing the dielectric relaxation spectroscopy over the frequency range from 20 Hz to 1 MHz. The influence of ZnO concentration on the degree of PVA crystalline phase and the crystallite size, surface morphology and roughness of the films, the glass phase transition and melting phase transition temperatures, direct and indirect optical energy band gap, refractive index, complex permittivity, electrical conductivity, activation energy and the structural dynamics of these PNC materials were explored. The investigated properties of the PNC films were credited to an innovation and engineering of novel high performance flexible nanodielectrics in the area of advanced functional materials for their promising applications especially in the next generation optoelectronic, gas sensor and microelectronic devices.
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      PubDate: 2018-06-03T15:37:56Z
       
  • Beryllium oxide (BeO) nanotube provides excellent surface towards adenine
           adsorption: A dispersion-corrected DFT study in gas and water phases
    • Abstract: Publication date: September 2018
      Source:Current Applied Physics, Volume 18, Issue 9
      Author(s): Mitra Sherafati, Ali Shokuhi Rad, Mehdi Ardjmand, Amir Heydarinasab, Majid Peyravi, Mahmoud Mirzaei
      Zigzag (5, 0) BeO nanotube (BeONT) has been examined in detail towards adsorption properties of adenine nucleobase on its surface via D2-DFT calculation method in the gas and water phases. A detailed surface study reveals that there are four orientations for nucleobase adsorption that none of the vibrational spectrums demonstrated imaginary frequency, recognizing that all of the relaxed structures are at the minimum of energy. The minimum and maximum adsorption energies are both in chemisorption regime with calculated values of −140 (−118 BSSE corrected) and −191 (−168 BSSE corrected) in the gas phase, and −181 and −310 kJ/mol in the water phase, using meta-hybrid functional (ꞷB97XD) and 6-31G** basis set. For all positions, BeONT showed p-type semiconducting property because of receiving electronic charge from adenine molecule. Our findings suggest that BeONT could be used as a possible strong carrier for adenine molecule in practical applications.
      Graphical abstract image

      PubDate: 2018-06-03T15:37:56Z
       
  • Precise temperature sensing with nanoscale thermal sensors based on
           diamond NV centers
    • Abstract: Publication date: Available online 2 June 2018
      Source:Current Applied Physics
      Author(s): Sunuk Choe, Jungbae Yoon, Myeongwon Lee, Jooeon Oh, Dongkwon Lee, Heeseong Kang, Chul-Ho Lee, Donghun Lee
      Sensing temperature with high precision and high spatial resolution is challenging and requires novel temperature measurement techniques. Recently, an atomic-scale thermal sensor based on a defect center in diamond, i.e., a nitrogen-vacancy (NV) center, has been developed, and successfully demonstrated temperature sensing at the mK level and a few tens of nanometers. Here we discuss a temperature sensing mechanism based on the NV center in both experimental and theoretical aspects. At room temperature, we show temperature sensing over a wide-range of temperatures ∼90 K with a precision of 0.2 K. We also map temperature gradients in a bridge-like device a few hundreds of micrometers long. In addition, we theoretically compare three sensing protocols and analyze temperature sensitivity to find optimal measurement time and NV concentration for the ensemble measurement.

      PubDate: 2018-06-03T15:37:56Z
       
  • Ab initio study of adsorption behaviors of molecular adsorbates on the
           surface and at the edge of MoS2
    • Abstract: Publication date: September 2018
      Source:Current Applied Physics, Volume 18, Issue 9
      Author(s): Janghwan Cha, Kyung-Ah Min, Dongchul Sung, Suklyun Hong
      Two dimensional (2D) semiconducting materials such as MoS2 have been actively investigated for their applications in nanodevices and gas sensors (or detectors). In this connection, we have investigated atomic and electronic structures of specific adsorbates on the surface of MoS2 and the edge of MoS2 armchair nanoribbons (ANRs) using density functional theory (DFT) calculations. Our calculations reveal that molecular adsorbates are well adsorbed at the edge of MoS2 than on the surface of MoS2. Despite the weak van der Waals (vdW) interaction between molecular adsorbates and MoS2 surface, paramagnetic molecules such as NO and NO2 induce the reduced band gap in MoS2 by making the states within the bandgap. On the other hand, adsorbed CO, NO, NO2, and O2 at the edge of MoS2 ANRs have much influence on the band structures of MoS2 ANRs via dissociation into their constituent atoms, while adsorbed CO2, NH3, H2, and N2 at the edge of MoS2 ANRs do not much change the band structure of MoS2 ANRs due to no dissociation. Further, we identify that dissociated molecules rearrange the charge densities of MoS2 ANRs by making the states within the bandgap.

      PubDate: 2018-05-31T15:24:16Z
       
  • Effect of fatigue fracture on the resistive switching of TiO2-CuO film/ITO
           flexible memory device
    • Abstract: Publication date: September 2018
      Source:Current Applied Physics, Volume 18, Issue 9
      Author(s): Jian-Chang Li, Bo Chen, Yu Qian
      We fabricated the GaIn/TiO2-CuO/ITO resistive memory and studied the effect of fatigue fracture on the switching performance. The device shows the stable bipolar resistive switching over 108 s under ambient condition. The ON/OFF ratio decreases seriously with increase of bending cycles. The main fatigue fracture caused by dynamic strain includes micro defect between nanoparticles, vertical crack along the film thickness and interfacial delamination between layers. Finite element analysis indicates that channel crack plays a key role to cause the interfacial delamination between function layer and ITO electrode. The channel crack and interfacial delamination can hinder the formation of tree−like conduction filaments. Moreover, oxygen via the cracks can be easily transformed to ions and reduce the density of oxygen vacancies under the catalytic assistance of CuO. Our studies may provide some useful information for inorganic materials applied in flexible nonvolatile memory.

      PubDate: 2018-05-31T15:24:16Z
       
  • Surface cleaning effect of NCM powder and improvement of lithium ion
           battery on the thermal stability and life cycle employing dielectric
           barrier discharge technique
    • Abstract: Publication date: September 2018
      Source:Current Applied Physics, Volume 18, Issue 9
      Author(s): Hyun Young Jeong, Yong Ho Jung, Dong Chan Seok, Seungryul Yoo, Sung Ku Kwon, Duksun Han
      Mixed NCM (nikel, cobalt, and manganese) powder was treated by a reactive gas from dielectric barrier discharge (DBD) to prepare a cathode material in Lithium ion (Li-ion) battery. The DBD was mainly sustained using N2 gas at atmospheric pressure, and NF3, SF6, and H2 was fed into the discharge to create the reactive gas. Compare to the non-treated sample, impurities on the surface of the NCM powder were significantly removed in a 5 min when the reactive gas was blow into the powder and mixed properly. F atom content on the surface was increased depending on the time duration of mixing, which form a LiF layer on the surface. Desirable LiF layer suppress a heat flow effectively , resulting a decreasing of exothermic temperature inside the Li-ion battery. Additionally, the treatment of NCM powder employing DBD technique was also contributed to electrochemical performance, which was confirmed by c-rate testing.

      PubDate: 2018-05-31T15:24:16Z
       
  • Nanometer-scale etching of CoFeB thin films using pulse-modulated high
           density plasma
    • Abstract: Publication date: September 2018
      Source:Current Applied Physics, Volume 18, Issue 9
      Author(s): Doo Hyeon Cho, Jae Yong Lee, Jae Sang Choi, Chee Won Chung
      Pulse-modulated inductively coupled plasma reactive ion etching of nanometer-scale patterned CoFeB thin films was performed in CH4/O2/Ar gas mixture. As the pulse on-off duty ratio decreased, the etch selectivity of CoFeB/TiN slightly increased and the etch profiles were improved. Moreover, the etch selectivity of the CoFeB films and the etch profiles were improved with the increase in the pulse frequency of the plasma. X-ray photoelectron spectroscopy revealed that during the pulse-modulated etching in the CH4/O2/Ar gas mixture, some polymeric layers were formed on the CoFeB films, which helped prevent the lateral etching and increased the etch selectivity. Consequently, nanometer-scale etching of CoFeB thin films patterned with TiN hard masks could be achieved using pulsed-modulated plasma in CH4/O2/Ar gas mixture.

      PubDate: 2018-05-31T15:24:16Z
       
  • A microfluidic binary logic device using inertia-elastic particle focusing
    • Abstract: Publication date: September 2018
      Source:Current Applied Physics, Volume 18, Issue 9
      Author(s): Sei Hyun Yang, Jae Ryoun Youn, Young Seok Song
      While a few attempts have been made on microfluidic logic devices, e.g., digital microfluidics and a fluid transistor, complete integration of digitalization into microfluidics is still a challenge. In this study, we investigate a microfluidic logic device that is built based on the particle dynamics in viscoelastic fluid. A logic gate system employing a Boolean function is implemented by utilizing multiple line particle focusing behavior in the microfluidic channel. The device is designed and fabricated to hydrodynamically control the logic operations of XOR, OR, AND, Buffer, and NOT under the fixed flow condition (e.g., flow rate, particle size, and fluid elasticity∼1.483). In addition, numerical simulation is carried out to understand the fundamental physics of the particle and fluid behavior in viscoelastic flow. Clear multiple particle focusing lines with high separation resolution ( R i j ∼ 6.19 ) were observed and the particle extraction at the outlets were analyzed by image-processing. This study is expected to open a new route to the incorporation of microfluidics with electronics by demonstrating logic gates based on microfluidics.
      Graphical abstract image

      PubDate: 2018-05-31T15:24:16Z
       
  • Energy level alignment of blended organic semiconductors and electrodes at
           the interface
    • Abstract: Publication date: September 2018
      Source:Current Applied Physics, Volume 18, Issue 9
      Author(s): T.J. Whitcher, W.S. Wong, A.N. Talik, K.L. Woon, A. Rusydi, N. Chanlek, H. Nakajima, T. Saisopa, P. Songsiriritthigul
      The energy level alignment of a blended mixture of organic semiconductors is often depicted as having a common vacuum level. However, this is not a universal phenomenon among the vast number of organic semiconductors that currently exist, as in many cases the energy levels align via the Fermi level. In this report, the energy level alignments of the mixtures; poly(9-vinylcarbazole) (PVK) and 2,7-bis(diphenylphosphoryl)-9,9′-spirobifluorene (SPPO13) and poly(3-hexylthiophene-2,5-diyl) (P3HT) and SPPO13, with varying SPPO13 concentrations, are measured. It was found that the blended systems exhibit two different vacuum levels with the dipole between the PVK and SPPO13 increasing with the SPPO13 concentration, whilst the P3HT and SPPO13 vacuum levels only experience a small change. This is attributed to the decreasing electronic screening with increasing SPPO13 concentration. These new observations have an important implication in our understanding of interfacial behaviour for blended systems commonly used in various organic electronic devices.

      PubDate: 2018-05-31T15:24:16Z
       
  • Morphological instabilities in argon ion sputtered CoSi binary mixtures
    • Abstract: Publication date: September 2018
      Source:Current Applied Physics, Volume 18, Issue 9
      Author(s): B.K. Parida, M. Ranjan, S. Sarkar
      Nanopattern formation on Co x Si1−x ( 0 < x < 1 ) surfaces has been studied under a range of low energy Ar+ ion bombardment at oblique incidence and also at varying ion fluences. Our study shows a clear morphological change for the nanostructures depending upon the incident beam energies and binary mixture stoichiometries. From an initial smoothening regime, well-ordered nanoscale ripples form at sub-keV energies at ion fluences ∼ 10 18 ions cm−2. These ripples further transform into micrometer-sized ellipsoidal structures upon increasing the ion energy from 500 eV to 1200 eV. The wavelengths of the nanostructures increase with ion fluence obeying a power law behaviour f 0.123 , where f is the fluence. For higher values of Co content, the rippled morphology is gradually replaced by bug-like hierarchical structures.
      Graphical abstract image

      PubDate: 2018-05-31T15:24:16Z
       
  • Indium doping effect on the magnetic properties of Y-type hexaferrite
           Ba0.5Sr1.5Zn2(Fe1-xInx)12O22
    • Abstract: Publication date: September 2018
      Source:Current Applied Physics, Volume 18, Issue 9
      Author(s): Min Zhang, Lihua Yin, Qiangchun Liu, Zhenfa Zi, Jianming Dai, Yuping Sun
      The effect of indium doping on structural and magnetic properties of Y-type hexaferrite Ba0.5Sr1.5Zn2(Fe1-x In x )12O22 (x = 0, 0.02, 0.04, 0.06, 0.08 and 0.1) prepared by the solid state reaction method was investigated. The Rietveld refinement method was used to analyze the X-ray diffraction patterns. The magnetic transition temperatures associated with the proper-screw spin phase to the collinear ferrimagnetic spin phase transition can be efficiently modulated by varying indium content. The magnetic transition temperature increases to a maximum with indium content x = 0.04 and then decreases with x, suggesting the possibility that electrically controlled magnetization reversal can be can be effectively tailored by varying indium content. The saturation magnetization at room temperature was decreased as increasing indium content, which can be explained as the metal ions occupation. It is worthy to note that the coercivity of In-doped samples was decreased drastically compared that of undoped sample, which is probably resulted from the reduction in anisotropy field with substitution of In3+ for Fe3+. The In-doped hexaferrite Ba0.5Sr1.5Zn2(Fe1-x In x )12O22 may be potential candidates for application in magnetoelectric devices.

      PubDate: 2018-05-31T15:24:16Z
       
  • Electrospun one-dimensional graphitic carbon nitride-coated carbon hybrid
           nanofibers (GCN/CNFs) for photoelectrochemical applications
    • Abstract: Publication date: September 2018
      Source:Current Applied Physics, Volume 18, Issue 9
      Author(s): Joonyoung Jang, Suhee Kang, Rajendra C. Pawar, Caroline Sunyong Lee
      Coupling of graphitic carbon nitride (GCN) with electrospun carbon nanofibers (CNFs) enhanced the photoelectrochemical (PEC) performance of a pristine GCN photoanode. Polyacrylonitrile (PAN) was electrospun to form fibers that were then carbonized to form one-dimensional (1D) CNFs, which were then used to fabricate the GCN structure. The optimum GCN/CNFs hybrid structure was obtained by controlling the amount of GCN precursors (urea/thiourea). The surface morphology of the hybrid structure revealed the coating of GCN on the CNFs. Additionally, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and X-ray diffraction confirmed the phases of the GCN/CNFs hybrids. PEC results showed a higher photocurrent of 3 μA for the hybrid compared with that of 1 μA for the pristine GCN. The high photocurrent for the hybrid structures indicated the formation of heterojunctions that resulted from a lower recombination rate of charge carriers. Moreover, UTh0.075 (0.075 g of urea and 0.075 g of thiourea) hybrid sample showed the highest performance of hydrogen generation with its numerical value of 437 μmol/g, compared to those of UTh0.1(0.1 g of urea and 0.1 g of thiourea) and UTh0.05 (0.05 g of urea and 0.05 g of thiourea) composite samples. This higher hydrogen production could be explained again with successful formation of heterojunctions between GCN and CNFs. Overall, we report a new approach for obtaining 1D hybrid structures, having better PEC performance than that of pristine GCN. These hybrids could potentially be used in energy-related devices.
      Graphical abstract image

      PubDate: 2018-05-31T15:24:16Z
       
  • Structure properties and electrical mechanisms of Si(001)/SiO2 interface
           with varying Si layer thickness in nano-scale transistor
    • Abstract: Publication date: September 2018
      Source:Current Applied Physics, Volume 18, Issue 9
      Author(s): Haixia Li, Aiming Ji, Canyan Zhu, Ling-Feng Mao
      To illustrate the impacts of stress/strain effect on nano-scale transistor, a theoretical investigation of stress/strain and transition region of interface are presented in this paper. It is found that the residual stress changes from −1.8098 to 0.3159 GPa with Si layer thickness increasing. At the same time, SiSi average bond length reduces from 2.397 Α ο to 2.355 Α ο and finally approaches to 2.352 Α ο (the bond length of ideal silicon crystal). The further calculations demonstrate that the above mentioned changes also decrease surface potential. And the relative decrease in the surface potential becomes larger with the applied gate voltage decreasing especially when it is less than 1.5 V. Moreover, when the doping concentration is 1 × 1019cm−3, the threshold voltage and subthreshold swing (SS) reduce from 2.9 V to 2 V and 551mV/dec to 198mV/dec respectively. It implies that we can get a better device performance by growing appropriate thickness of silicon.
      Graphical abstract image

      PubDate: 2018-05-31T15:24:16Z
       
  • Reduced graphene oxide/strontium titanate heterostructured nanocomposite
           as sunlight driven photocatalyst for degradation of organic dye pollutants
           
    • Abstract: Publication date: September 2018
      Source:Current Applied Physics, Volume 18, Issue 9
      Author(s): A. Rosy, G. Kalpana
      Reduced graphene oxide/Strontium titanate (RGO/SrTiO3) heterostructured nanocomposite was synthesized by coupling Hummer's synthesized graphene oxide (GO) with hydrothermally synthesized SrTiO3 nanoparticles (SrTiO3) through a facile and unique high energy ultrasonication technique using triple solvents. XRD result confirmed the successful formation of pure, single phase and primitive cubic crystal structure RGO/SrTiO3 heterostructured nanocomposite. SEM result confirmed the successful intercalation of SrTiO3 nanoparticles over the two dimensional networks of RGO nanosheets. The synergistic and beneficial interactions between SrTiO3 and RGO resulted in smaller crystallite size (53 nm), reduced band gap (2.87 eV) and larger specific surface area (31 m2/g) than that of as prepared pure SrTiO3 nanoparticles. RGO strongly influenced the photocatalytic activity of SrTiO3 and hence RGO/SrTiO3 heterostructured nanocomposite exhibited greater efficiency in degrading Rhodamine B (RhB) and Rose Bengal (RB) organic dye pollutants under natural sunlight irradiation than that of pure SrTiO3 nanoparticles.

      PubDate: 2018-05-31T15:24:16Z
       
  • Conversion of the valence states of Eu ions in YVO4 with the gamma-ray
           irradiation
    • Abstract: Publication date: August 2018
      Source:Current Applied Physics, Volume 18, Issue 8
      Author(s): Junhwi Lim, Ye-Eun Na, Y.S. Lee, Sang Don Bu
      We investigated the effect of the gamma-ray irradiation on the emission property of the Eu ion doped YVO4. We clearly observed that on exposure to the gamma-ray, sharp emission peaks originating from the Eu3+ ions were suppressed dramatically. Instead, a broad emission feature near 470 nm, which was attributed to the Eu2+ ions, emerged. The quantitative analysis on the emission spectra suggest that the valence state of the Eu ions in our samples was changed from 3 + to 2 + by the gamma-ray irradiation. The conversion of the valence state of the Eu ions was closely related to the formation of the oxygen vacancies induced by the gamma-ray irradiation.

      PubDate: 2018-05-31T15:24:16Z
       
  • Application of Mn nano-flower sculptured thin films produced on
           interdigitated pattern as cathode and anode electrodes in field ionization
           gas sensor
    • Abstract: Publication date: August 2018
      Source:Current Applied Physics, Volume 18, Issue 8
      Author(s): Hadi Savaloni, Rojan Savari, Salar Abbasi
      The photolitography method was used for producing interdigitated configurations for cathode and anode electrodes of a field ionization gas sensor in which Mn helical nano-flowers with 3-fold symmetry were deposited using oblique angle deposition together with rotation of the substrate about its surface normal, with each rotation divided into six sections. These sections were alternately rotated at high and low speeds. Three different distances were chosen in the design between anode and cathode electrodes, namely 40, 100 and 200 μm. Physical structure and morphology of electrodes were studied by field emission scanning electron microscope and atomic force microscope analyses. The breakdown voltage of the system was studied for nitrogen, oxygen, argon, air and carbon mono-oxide gases. Investigations with these gases at different distances between anode and cathode and different gas pressures confirmed Paschen's Law. Results showed that at low pressures, decreasing the gap between electrodes increases the breakdown voltage. With fewer gas molecules between the electrodes the number of interactions between particles is reduced and higher energies are required for ionization of gas molecules. At high pressures, the breakdown voltage is decreased because of an increased number of molecular interactions. The sensor demonstrated good selectivity between the different gases and selectivity was enhanced with increasing gas pressure. A direct relationship was found at low pressures (e.g., 0.1 mbar) between the breakdown voltage and the gas ionization energy while at high pressures (e.g., 1000 mbar) this relationship was reversed.
      Graphical abstract image

      PubDate: 2018-05-31T15:24:16Z
       
  • Mechanical properties of thin films of graphene materials: A study on
           their structural quality and functionalities
    • Abstract: Publication date: August 2018
      Source:Current Applied Physics, Volume 18, Issue 8
      Author(s): Velram Balaji Mohan, Hamid Souri, Krishnan Jayaraman, Debes Bhattacharyya
      Several studies have been done on physiochemical properties of thin films of graphene materials, but less on their mechanical properties. The mechanical properties such as tensile and storage modulus of films of graphene oxide (GO), different reduced graphene oxides (rGO), functionalised reduced graphene oxide (frGO) and a few layers graphene (graphene) were analysed in this study. During syntheses processes, a range of variations occurs due to different reducing agents and functionalising components used; this affects or changes the mechanical properties of the materials. In addition, it has become vital to comprehend the mechanical properties of these films as the potential applications such as sensor and electrodes demand extended life cycles or lifetime. It has been found that the ultimate tensile strength (UTS), tensile modulus, and storage modulus vary across all the samples that highly depend on nature/efficiency of reducing agent used, amount of impurities such as oxygen functional groups and defect density such as discrepancies/holes in the aromatic structure. The highest UTS and modulus have been identified with a few layers graphene and with hydroiodic acid reduced GO among the rGOs. The frGO shows almost similar properties to that of graphene.
      Graphical abstract image

      PubDate: 2018-05-31T15:24:16Z
       
  • The effect of annealing temperature on the morphology and piezoelectric
           characteristics of BaTiO3 nanofibers and domain switching under different
           temperatures
    • Abstract: Publication date: August 2018
      Source:Current Applied Physics, Volume 18, Issue 8
      Author(s): Zhe Zhu, Weiming Zhu
      Effects of annealing temperature (600–750 °C) on crystalline structure, the morphology and piezoresponse hysteresis loops of BaTiO3 nanofibers prepared by electrospinning are characterized by X-ray diffraction, scanning electronic microscopy, transmission electron microscope and piezoresponse force microscope. When the annealing temperature is 700 °C, the nanofibers become smoother and have a diameter of 100–300 nm. Meanwhile the typical butterfly-shaped amplitude loop and 180°phase change represents the best ferroelectric and piezoelectric properties at 700 °C. So the 700 °C was found to be optimum for good piezoelectric characteristics at annealing temperature of 600 °C–750 °C. In order to give more clear evolution of domain states at different external fields, the three dimensional topographic and phase images of the nanofiber at different temperatures are observed by piezoresponse force microscope. The 90° domain switching is observed during heating from room temperature to 125 °C and the domain switching tends to be stable when the temperature exceeds a critical value. The thermal stress due to the high temperatures is responsible for switching mechanism from the perspective of equilibrium state free energy. This work suggests that the temperature variation should be considered while designing the ferroelectric devices based on one dimensional material.

      PubDate: 2018-05-31T15:24:16Z
       
  • Effect of Ga alloying on thermoelectric properties of InSb
    • Abstract: Publication date: August 2018
      Source:Current Applied Physics, Volume 18, Issue 8
      Author(s): Zhengliang Du, Xiaolu Chen, Junhao Zhu, Jiaolin Cui
      As a potential thermoelectric (TE) material, the high lattice thermal conductivity and relatively low weighted mobility severely limit TE property optimization of InSb binary compound. In this paper, we substituted In of InSb with Ga and systematically investigated the effect of Ga alloying on the Seebeck coefficient, electrical conductivity and lattice thermal conductivity of InSb between 300 K and 770 K. We found that Ga alloying simultaneously reduced the lattice thermal conductivity and optimized the weighted mobility of InSb. The lattice thermal conductivity has been analyzed using Abeles model to gain more insight on the roles of Ga in In1-x Ga x Sb(x = 0, 0.1, 0.15, 0.2) solid solution. The synergetic effect of Ga alloying on the electron and phonon transport leads to a marked enhancement in TE potential of InSb. The dimensionless figures of merit of InSb and In0.8Ga0.2Sb reach, respectively, 0.54 and 0.52 at 770 K.

      PubDate: 2018-05-31T15:24:16Z
       
  • One-step synthesis of Pt-Pd catalyst nanoparticles supported on few-layer
           graphene for methanol oxidation
    • Abstract: Publication date: August 2018
      Source:Current Applied Physics, Volume 18, Issue 8
      Author(s): Hongxia Wang, Leimei Sheng, Xinluo Zhao, Kang An, Zhongmin Ou, Yanghao Fang
      In this study, Pt-Pd nanoparticles (NPs) supported on few-layer graphene (FLG) have been firstly prepared by one-step arc discharge evaporation of carbon electrodes containing both Pt and Pd elements. The few-layer graphene and Pt-Pd nanoparticles were achieved simultaneously through the evaporation process. After a high-temperature hydrogen treatment, the Pt-Pd/graphene was applied in the study of methanol oxidation in direct methanol fuel cell. The total weight of electrocatalyst keeps 2 wt% of the electrode. The sample with a mass ratio of Pt:Pd = 3:1 (H-Pt3Pd1/G) exhibits better electrocatalytic activity (198 mA mg-1 pt) and better tolerance to carbon monoxide(CO) poisoning (I f/I b = 1.26). It is noteworthy that the value of I f/I b can reach to 1.55 for the sample with the mass ratio of Pt:Pd = 2:1 (H-Pt2Pd1/G),which implies its excellent ability of CO tolerance. The introduction of Pd element may open a new strategy to improve the CO tolerance by arc discharge evaporation.

      PubDate: 2018-05-31T15:24:16Z
       
  • Analysis of the energy extracted by a harvester based on a piezoelectric
           tile
    • Abstract: Publication date: August 2018
      Source:Current Applied Physics, Volume 18, Issue 8
      Author(s): Furio Cascetta, Alessandro Lo Schiavo, Aldo Minardo, Marilena Musto, Giuseppe Rotondo, Alessio Calcagni
      In this paper, we analyze the maximum energy that can be extracted from a piezoelectric harvester subject to pulsed excitation, with an interface circuit composed by a standard bridge rectifier. We show that the optimal voltage of the DC load of the bridge rectifier is a fraction, comprised between 1/3 and ½, of the open-circuit voltage, depending on the piezoelectric losses and excitation time. A simple analytical model is provided, whose accuracy has been assessed against SPICE simulations. Furthermore, preliminary experimental tests carried out over a commercial piezoelectric tile confirm the validity of the proposed model.

      PubDate: 2018-05-31T15:24:16Z
       
  • A new simple route to grow Cu(In,Ga)Se2 thin films with large grains in
           the co-evaporation process
    • Abstract: Publication date: August 2018
      Source:Current Applied Physics, Volume 18, Issue 8
      Author(s): Seung Tae Kim, Kihwan Kim, Jae Ho Yun, Byung Tae Ahn
      In the conventional three-stage co-evaporation process to grow Cu(In,Ga)Se2 (CIGS) film, a large grain is achieved by the co-evaporation of Cu and Se on (In,Ga)2Se3 layer at 550 °C in the second stage and then a p-type is achieved by the co-evaporation of In, Ga, and Se in the third-stage. We reported a new process where a CIGS film with a large gain and p-type is achieved by evaporation of Cu only in the second stage at 400 °C and by the Se annealing in the third stage. In the new process, thermal budget was lowered and the third-stage co-evaporation process was eliminated. It was found that the CIGS gain size increased when the Cu/(In + Ga) ratio was above 0.7 and an addition thin CIGS layer appeared on the CIGS surface. The reaction path with Cu was described in the Cu-In-Se ternary phase diagram. The cell conversion efficiency increased from 9.6 to 15.4% as the Se annealing temperature increased from 400 to 550 °C in the third stage, mainly due to the increase of open-circuit voltage and fill factor. Our process demonstrated a new route to grow a CIGS film with a less thermal budget and simpler process in the co-evaporation process.
      Graphical abstract image

      PubDate: 2018-05-31T15:24:16Z
       
  • Engineering of AlON interlayer in Al2O3/AlON/In0.53Ga0.47As gate stacks by
           thermal atomic layer deposition
    • Abstract: Publication date: August 2018
      Source:Current Applied Physics, Volume 18, Issue 8
      Author(s): Woo Chul Lee, Cheol Jin Cho, Suk-In Park, Dong-Hwan Jun, Jin Dong Song, Cheol Seong Hwang, Seong Keun Kim
      The presence of an AlN interfacial layer in high-k/In0.53Ga0.47As gate stacks improves the interfacial properties and enhances the electrical performance of devices. However, pure AlN is rarely grown by atomic layer deposition (ALD) because of the low reactivity of NH3 toward the common Al-precursor and the predisposition to oxidation of the grown AlN layer. Although a plasma-enhanced ALD technique significantly suppresses the oxygen content in the grown AlN layer, the deterioration of the interface properties by plasma-damage is a critical issue. In this work, an AlON interlayer was engineered by optimizing the NH3 feeding time in thermal ALD to improve the interface quality in Al2O3/AlON/In0.53Ga0.47As capacitors. It was determined that a mere increase in the NH3 feeding time during the ALD of the AlON film resulted in a higher nitrogen incorporation into the AlON interlayer, leading to a reduction in the interface trap density. Furthermore, the out-diffusion of elements from the In0.53Ga0.47As layer was effectively suppressed by increasing the NH3 feeding time. This work demonstrates that simple process optimization can improve the interface quality in high-k/In0.53Ga0.47As gate stacks without the use of any plasma-activated nitrogen source.
      Graphical abstract image

      PubDate: 2018-05-31T15:24:16Z
       
  • Elimination of endurance degradation by oxygen annealing in bilayer
           ZnO/CeO2-x thin films for nonvolatile resistive memory
    • Abstract: Publication date: August 2018
      Source:Current Applied Physics, Volume 18, Issue 8
      Author(s): Muhammad Ismail, Shazia Jabeen, Tahira Akber, Ijaz Talib, Fayyaz Hussain, Anwar Manzoor Rana, Muhammad Hussain, Khalid Mahmood, Ejaz Ahmed, Dinghua Bao
      Effect of oxygen annealing on bipolar resistive switching (BRS) properties of TiN/ZnO/CeO2-x/Pt devices was investigated. Bilayer ZnO/CeO2-x thin films were fabricated by rf-magnetron sputtering. It was observed that the improvement in cycle-to-cycle endurance degradation and uniformity of the bilayer ZnO/CeO2-x thin film is optimum at 400 °C annealing temperature due to decrease in oxygen vacancies during annealing, as confirmed by x-ray photoelectron spectroscopy. The BRS could be caused by the formation of interfacial TiON layer, which is most likely to be accountable for creating an adequate quantity of oxygen vacancies necessary for the formation and rupture of conductive filaments. Smaller Gibbs free energy of the formation of interfacial TiON ( − 611 k J m o l − 1 ) layer as compared to bilayer film ZnO ( − 650 k J m o l − 1 ) and CeO2 ( − 1024 k J m o l − 1 ) results in an easier re-oxidation of the filaments through the oxygen exchange with TiN top electrode. The analysis of current–voltage characteristics shows that the charge transport mechanism is Schottky emission. Moreover, the temperature dependence of high resistance state (HRS) and low resistance state (LRS) revealed the physical origin of the RS mechanism, which entails the oxygen vacancies for the formation and rupture of conducting paths.

      PubDate: 2018-05-31T15:24:16Z
       
  • Simultaneously depositing polyaniline onto bacterial cellulose nanofibers
           and graphene nanosheets toward electrically conductive nanocomposites
    • Abstract: Publication date: August 2018
      Source:Current Applied Physics, Volume 18, Issue 8
      Author(s): Yizao Wan, Jin Li, Zhiwei Yang, Haiyong Ao, Lingling Xiong, Honglin Luo
      In this study, we report the construction of a ternary flexible nanocomposite of bacterial cellulose/graphene/polyaniline (BC/GE/PANI) via a facile two-step strategy. Bacterial cellulose/graphene (BC/GE) is first prepared by a novel in situ membrane-liquid-interface method, in which the three-dimensional continuous BC nanofibers can be maintained and the introduced GE can improve the mechanical properties mainly due to the uniform dispersion of GE in the BC matrix. To construct the effectively interconnected conductive paths between separated GE nanosheets, polyaniline (PANI) is simultaneously deposited on the surfaces of both BC nanofibers and GE nanosheets to obtain BC/GE/PANI with excellent electrical conductivity. It is found that the as-prepared BC/GE/PANI has an electrical conductivity of 1.7 ± 0.1 S cm−1, which is higher than most of PANI-based composites. It is believed that the BC/GE/PANI nanocomposite possesses great potential for applications in electromagnetic shielding and flexible electrodes.
      Graphical abstract image

      PubDate: 2018-05-31T15:24:16Z
       
  • Variation of photoluminescence spectral line shape of monolayer WS2
    • Abstract: Publication date: August 2018
      Source:Current Applied Physics, Volume 18, Issue 8
      Author(s): Yongjae Kwon, Kangwon Kim, Wontaek Kim, Sunmin Ryu, Hyeonsik Cheong
      The origin of the variation of photoluminescence (PL) spectra of monolayer tungsten disulfide (WS2) is investigated systematically. Dependence of the PL spectrum on the excitation power show that the relatively sharp component corresponds to excitons whereas the broader component at slightly lower energy corresponds to negatively charged trions. PL imaging and second harmonic generation measurements show that the trion signals are suppressed more than the exciton signals near the edges, thereby relatively enhancing the excitonic feature in the PL spectrum and that such relative enhancement of the exciton signals is more pronounced near approximately armchair edges. This effect is interpreted in terms of depletion of free electrons near the edges caused by structural defects and adsorption of electron acceptors such as oxygen atoms.

      PubDate: 2018-05-31T15:24:16Z
       
  • Gold and ytterbium interfacing effects on the properties of the
           CdSe/Yb/CdSe nanosandwiched structures
    • Abstract: Publication date: August 2018
      Source:Current Applied Physics, Volume 18, Issue 8
      Author(s): S.R. Alharbi, A.F. Qasrawi
      Owing to the performance of the CdSe as an optoelectronic material used for the production of quantum dots, photosensors and wave traps we here, in this article, report the enhancements in structural and electrical properties that arises from the nanosandwiching of a 40 nm thick Yb film between two films of CdSe (CYbC-40). The CdSe films which were deposited onto glass, Yb and Au substrates are characterized by X-ray diffraction, temperature dependent electrical conductivity and impedance spectroscopy measurements in the frequency range of 10–1800 MHz. The analysis of the XRD patterns have shown that the glass/CdSe/Yb/CdSe films exhibit larger grain size and lower strain, defect density and lower stacking faults compared to the not sandwiched CdSe. In addition, it was observed that the Yb shifts the donor states of the n-type CdSe from 0.44 to 0.29 eV leading to a modification in the built in voltage of the material. On the other hand, the design of the energy band diagram has shown the ability of the formation of the Au/CYbC-40/Yb as Schottky (SB) and the Au/CYbC-40/Au as back to back Schottky barriers (BBSB). While the SB device show low band pass filter characteristics, the BBSB device performed as band stop filters. The BBSB device exhibited negative capacitance effects with filtering features that reveal a return loss of 42 dB at ∼1440 MHz.

      PubDate: 2018-05-31T15:24:16Z
       
  • Nanoporous gold: Preparation and applications to catalysis and sensors
    • Abstract: Publication date: July 2018
      Source:Current Applied Physics, Volume 18, Issue 7
      Author(s): Sang Hoon Kim
      Preparation and applications of nanoporous gold (NPG) were reviewed. Various preparation methods of NPG and its structure were first discussed. Then, two basic characterization methods for morphology and surface area of prepared NPG structures were discussed. As for applications of NPG, studies regarding catalysts and sensors were surveyed. First, for catalysis, CO oxidation and hydrogen oxidation were reviewed. Regarding CO oxidation, detailed studies on reaction mechanisms and density functional theory (DFT) calculations were also discussed. For hydrogen oxidation, the effect of adding metal oxide nanoparticles on NPG was discussed. As for sensor applications, non-enzymatic and amperometric electrochemical sensing of aniline and phenol were reviewed. Due to its nanostructures, NPG had superior properties of antifouling effect and enhanced response signals and good enough stability that enabled amperometric sensing.

      PubDate: 2018-05-31T15:24:16Z
       
  • Study on the measurement accuracy of circular transmission line model for
           low-resistance Ohmic contacts on III-V wide band-gap semiconductors
    • Abstract: Publication date: July 2018
      Source:Current Applied Physics, Volume 18, Issue 7
      Author(s): Tong Liu, Rong Huang, Fangsen Li, Zengli Huang, Jian Zhang, Jianping Liu, Liqun Zhang, Shuming Zhang, An Dingsun, Hui Yang
      The accuracy and error propagation for determining the low specific contact resistance of Ohmic contacts on III-V wide band-gap semiconductors based on the circular transmission line model have been analyzed and the validity of this method is discussed in detail. The accuracy is more susceptible to the factors including data fitting method, electrical measurement technique and contact area correction. By using the equations of the original circular transmission line model to extract the fitting parameters, the calculation accuracy is much improved and the inapplicability of the linear least-square fitting is prevented. To further improve the accuracy, a four-probe current-voltage measurement technique was adopted to reduce the parasitic series resistances and the uncertainty bound, especially for the Ohmic contact with low sheet resistance of the semiconductor. Moreover, we have studied the size effect of contact pads of patterns and demonstrated that contact area correction is necessary for the semiconductor with high sheet resistance. A comprehensive error analysis is also performed to fully understand all the impact factors on this advanced method of specific contact resistance measurement, which is benefit for device performance evaluation and failure analysis.

      PubDate: 2018-05-31T15:24:16Z
       
  • The mechanism of photocurrent enhancement of ZnO ultraviolet photodetector
           by reduced graphene oxide
    • Authors: Tiantian Yang; Bin Sun; Lei Ni; Xing Wei; Tingting Guo; Zhemin Shi; Fei Han; Li Duan
      Abstract: Publication date: Available online 13 April 2018
      Source:Current Applied Physics
      Author(s): Tiantian Yang, Bin Sun, Lei Ni, Xing Wei, Tingting Guo, Zhemin Shi, Fei Han, Li Duan
      An ultraviolet (UV) photodetector based on ZnO-reduced graphene oxide (ZnO-rGO) composites have been successfully fabricated. A pure ZnO photodetector was also fabricated by similar method. In comparison with the pure ZnO UV photodetector, the ZnO-rGO photodetector exhibits a much larger photocurrent and a better light-to-dark-current-ratio. The mechanism of photocurrent enhancement was investigated using I-V characteristics, photoluminescence (PL) spectra, transmittance spectra and time-dependent photocurrent analysis. Results show that the photocurrent enhancement of the ultraviolet photodetector is due to the improvement of the carrier lifetime, because the carrier recombination of ZnO were reduced by rGO. It provides a potential way to fabricate high-response UV photodetectors.

      PubDate: 2018-04-15T10:39:07Z
      DOI: 10.1016/j.cap.2018.04.010
       
 
 
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