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wide-band-gap-semiconductors
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Frozen leg operation of a three-phase dual active bridge DC/DC converter at light loads
, Article Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC ; Volume 2018-March , 18 April , 2018 , Pages 3385-3391 ; 9781538611807 (ISBN) ; Blaabjerg, F ; Yazdani, F ; Bahman, A. S ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
A three-phase dual active bridge (DAB) converter is designed and constructed as the DC/DC stage of a 50 kW fast charger station. Recently introduced 300A SiC power modules and drivers are utilized in the converter to obtain a high efficiency. Each module has two interconnected switches with anti-parallel diodes resembling a converter leg. It is observed that the driver halts the module operation as a result of protective actions such as over-current, gate under-voltage, or gate overvoltage. In such case the module operates as a leg with two diodes until an external hardware signal resets the driver. The aim of this paper is to provide analysis, simulation and experiments for a three-phase...
Common Mode Noise Reduction of LLC Resonant Converter with Planar Transformer for Electric Vehicle Applications
, M.Sc. Thesis Sharif University of Technology ; Tahami, Farzad (Supervisor)
Abstract
converters in electric vehicles, it is necessary to reduce their dimensions and increase their efficiency. It is expected that in the near future wide band gap semiconductors will be used to achieve these goals. On the other hand, usage of planar transformers is necessary to achieve slim and compact converter designs in electric vehicles. Clearly, planar transformers offer a significant advantage in replacing bulky wired transformers in high frequency LLC resonant converters with WBG transistors. planar transformers also have several other advantages, including low flux leakage, modular structure, and low thermal resistance.However, in planar transformers, due to the proximity and large area...
Sonochemical synthesis and measurement of optical properties of zinc sulfide quantum dots
, Article Chemical Engineering Journal ; Volume 209 , 2012 , Pages 113-117 ; 13858947 (ISSN) ; Sajjadi, S. H ; Mehrkhah, R ; Nancarrow, P ; Sharif University of Technology
2012
Abstract
A facile sonochemical method has been developed to prepare very small zinc sulfide nanoparticles (ZnS NPs) of extremely small size about 1. nm in diameter using a set of ionic liquids based on the bis (trifluoromethylsulfonyl) imide anion and different cations of 1-alkyl-3-methyl-imidazolium. The structural features and optical properties of the NPs were determined in depth with X-ray powder diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), Fourier transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS) analysis, and UV-vis absorption spectroscopy. The energy band gap measurements of ZnS NPs were calculated by UV-vis absorption...
Band-gap narrowing and electrochemical properties in N-doped and reduced anodic TiO2 nanotube arrays
, Article Electrochimica Acta ; Volume 270 , 2018 , Pages 245-255 ; 00134686 (ISSN) ; Khameneh Asl, S ; Mohammadpour, R ; Khameneh Asl, S ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Electrochemical activity of TiO2 nanotube arrays (NTAs) is restricted by a wide band gap of TiO2. To overcome this restriction, we considered systematic research on two effective methods of doping of TiO2 NTAs such as the N-doping and electrochemical reductive doping and predicting the proper application of them. Band gap narrowing was occurred from 3.16 eV for undoped TiO2 NTAs to 2.9 and 2.7 eV at N-doped and self-doped TiO2 ones respectively. The electrochemical responses of the TiO2 NTAs before and after doping were examined by cyclic Voltammetry (CV) curve. To understand the electrochemical behavior of the undoped and doped TiO2 NTAs, electrochemical impedance spectroscopy (EIS) was...
Real-space exciton distribution in strained-siligraphene g-SiC7
, Article Journal of Applied Physics ; Volume 126, Issue 6 , 2019 ; 00218979 (ISSN) ; Ebrahimi, M. R ; Davoudiniya, M ; Yarmohammadi, M ; Sharif University of Technology
American Institute of Physics Inc
2019
Abstract
Siligraphene belonging to the family of two-dimensional (2D) materials has great potential in optoelectronics due to its considerable excitonic effects. In this study, the strain effects on the electronic structure and the real-space exciton wave functions of g - SiC 7 are investigated using the first-principles calculations based on the ab initio many-body perturbation theory. Alongside the increase (decrease) of the bandgap with compressive (tensile) strain, our results show that the exciton in the siligraphene monolayer under in-plane biaxial compressive strains is much more localized than that in the case of tensile one, leading to the higher and lower exciton binding energies,...
Design and tailoring of one-dimensional ZnO nanomaterials for photocatalytic degradation of organic dyes: a review
, Article Research on Chemical Intermediates ; Volume 45, Issue 4 , 2019 , Pages 2197-2254 ; 09226168 (ISSN) ; Zirak, M ; Naseri, A ; Kheirabadi, M ; Ebrahimi, M ; Moshfegh, A. Z ; Sharif University of Technology
Springer Netherlands
2019
Abstract
Abstract: Photocatalysis using semiconductors has emerged as a promising wastewater treatment process to overcome the major challenges faced by conventional technologies. The advantages of ZnO nanomaterials over other semiconductors, and their structure-dependent properties, make them important building blocks in nanotechnology as multifunctional materials. Moreover, it has been confirmed that ZnO nanomaterials can exhibit high performance in photodegradation of organic dyes for treatment of industrial effluent. The wurtzite structure of ZnO contains polar and nonpolar planes; the low surface energy and thermodynamic stability of the nonpolar planes enable formation of one-dimensional (1D)...
Surface/edge functionalized boron nitride quantum dots: Spectroscopic fingerprint of bandgap modification by chemical functionalization
, Article Ceramics International ; Volume 46, Issue 1 , 2020 , Pages 978-985 ; Shayeganfar, F ; Hasanzadeh Azar, M ; Simchi, A ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Promising properties of boron nitride nanomaterials such as their chemical, thermal, and mechanical stability have made them suitable materials in a various range of applications. However, their low electrical conductivity and wide bandgap, particularly in the case of boron nitride quantum dots (BNQDs), have given rise to severe limitations. Efforts on bandgap engineering through doping and surface functionalization have gained little success due to their high thermodynamic stability and inertness. Herein, we present a novel approach to functionalize BNQDs by hydroxyl, methyl, and amine functional groups aiming to adjust the electronic structure. The successful exfoliation is demonstrated by...
Optical properties, microstructure, and multifractal analyses of ZnS thin films obtained by RF magnetron sputtering
, Article Journal of Materials Science: Materials in Electronics ; Volume 31, Issue 7 , 2020 , Pages 5262-5273 ; Arman, A ; Ţălu, Ş ; Ghosh, K ; Rezaee, S ; Luna, C ; Mwema, F ; Sherafat, K ; Salehi, M ; Mardani, M ; Sharif University of Technology
Springer
2020
Abstract
The morphology, structure and optical properties of zinc sulfide (ZnS) thin films prepared through radio-frequency (RF) magnetron sputtering have been analyzed using atomic force microscopy (AFM), UV–Vis–NIR spectrophotometry, X-ray diffraction, and multifractal analyses. The X-ray diffraction patterns revealed that all ZnS thin films show a single peak at around 29.6°, which has been ascribed to the (111) planes of sphalerite phase, indicating that the growth direction of the films is the [111] direction. UV–Vis–NIR transmittance spectra were used to determine the refractive index of the samples, their thickness, and their band gap energy, showing the optical and semiconductor properties a...
Enhanced photocatalytic activity of ZnO/g-C3N4 nanofibers constituting carbonaceous species under simulated sunlight for organic dye removal
, Article Ceramics International ; Volume 47, Issue 18 , 2021 , Pages 26185-26196 ; 02728842 (ISSN) ; Samadi, M ; Pourjavadi, A ; Ramakrishna, S ; Moshfegh, A. Z ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Semiconductor-based photocatalysis is an efficient approach for degradation of organic pollutants. In this context, ZnO/g-C3N4 composite nanofibers containing carbonaceous species with different concentrations of g-C3N4 nanosheets (x = 0.25, 0.5, 1, 2, 10 wt%) noted as ZnO/carbon/(x wt%) g-C3N4 are prepared by electrospinning technique. For preparation of the composite nanofibers, bulk g-C3N4 is exfoliated to nanosheets, and then it is mixed with polyvinyl alcohol and appropriate zinc acetate content followed by electrospinning process. Thermal annealing of the as spun zinc acetate/poly(vinyl alcohol)/g-C3N4 nanosheets sample under N2 atmosphere leads to the formation of carbonaceous species...
High-Voltage, high-current electrical switching discharge synthesis of ZnO nanorods: A new method toward rapid and highly tunable synthesis of oxide semiconductors in open air and water for optoelectronic applications
, Article ACS Applied Materials and Interfaces ; Volume 13, Issue 39 , 2021 , Pages 46951-46966 ; 19448244 (ISSN) ; Abrari, M ; Karimi, V ; Shafiee, M ; Ghollamhosseini, S ; Taheri Ghahrizjani, R ; Ahmadi, M ; Wang, D ; Sun, H ; Soltanmohammadi, M ; Imani, A ; Ghanaatshoar, M ; Mohseni, S. M ; Taghavinia, N ; Sharif University of Technology
American Chemical Society
2021
Abstract
A novel method of oxide semiconductor nanoparticle synthesis is proposed based on high-voltage, high-current electrical switching discharge (HVHC-ESD). Through a subsecond discharge in the HVHC-ESD method, we successfully synthesized zinc oxide (ZnO) nanorods. Crystallography and optical and electrical analyses approve the high crystal-quality and outstanding optoelectronic characteristics of our synthesized ZnO. The HVHC-ESD method enables the synthesis of ZnO nanorods with ultraviolet (UV) and visible emissions. To demonstrate the effectiveness of our prepared materials, we also fabricated two UV photodetectors based on the ZnO nanorods synthesized using the subsecond HVHC-ESD method. The...
N-Type conductive small molecule assisted 23.5% efficient inverted perovskite solar cells
, Article Advanced Energy Materials ; Volume 12, Issue 34 , 2022 ; 16146832 (ISSN) ; Li, Y ; Zhang, Y ; Zhao, J ; Wang, T ; Yang, B ; Pu, X ; Yang, J ; Chen, H ; Chen, X ; Li, X ; Ghasemi, S ; Salari, H ; Hagfeldt, A ; Li, X ; Sharif University of Technology
John Wiley and Sons Inc
2022
Abstract
Because of the compatibility with tandem devices and the ability to be manufactured at low temperatures, inverted perovskite solar cells have generated far-ranging interest for potential commercial applications. However, their efficiency remains inadequate owing to various traps in the perovskite film and the restricted hole blocking ability of the electron transport layer. Thus, in this work, a wide-bandgap n-type semiconductor, 4,6-bis(3,5-di(pyridin-4-yl)phenyl)-2-phenylpyrimidine (B4PyPPM), to modify a perovskite film via an anti-solvent method is introduced. The nitrogen sites of pyrimidine and pyridine rings in B4PyPPM exhibit strong interactions with the undercoordinated lead ions in...
Shape-Controlled photochemical synthesis of noble metal nanocrystals based on reduced graphene oxide
, Article ACS Applied Materials and Interfaces ; Volume 14, Issue 14 , 2022 , Pages 16527-16537 ; 19448244 (ISSN) ; Naseri, A ; Li, T ; Ostovan, A ; Asadian, E ; Jia, R ; Shi, L ; Huang, L ; Moshfegh, A. Z ; Sharif University of Technology
American Chemical Society
2022
Abstract
The fabrication of supported noble metal nanocrystals (NCs) with well-controlled morphologies have been attracted considerable interests due to their merits in a wide variety of applications. Photodeposition is a facile and effective method to load metals over semiconductors in a simple slurry reactor under irradiation. By optimizing the photodeposition process, the size, chemical states, and the geometrical distribution of metal NCs have been successfully tuned. However, metal NCs with well-controlled shapes through the photodeposition process have not been reported until now. Here, we report our important advances in the controlled photodeposition process to load regular noble metal NCs....
Partly semiconductor covered vane fast magnetron
, Article IEEE Transactions on Plasma Science ; Volume 50, Issue 5 , 2022 , Pages 1179-1187 ; 00933813 (ISSN) ; Hashemi, S. M. A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
Alterations in the structure of a magnetron, e.g., the A6 relativistic magnetron, are proposed, which considerably increase the device's build-up speed. We cover the magnetron vane surfaces with semiconductor layers of nonzero electric conductivity, with an exact geometrical design. Semiconductor layers with considerable mechanical strength also provide excellent shielding for the vanes against the high-energy relativistic electrons' bombardment. The novel structure introduces several new free parameters to the magnetron design procedure and considerably increases the design flexibility. A multistage exact optimization procedure, performed by extensive computer simulations, shows that...
Surface modification of carbon steel by ZnO-graphene nano-hybrid thin film
, Article Surface and Coatings Technology ; Volume 363 , 2019 , Pages 1-11 ; 02578972 (ISSN) ; Ghorbani, M ; Sharif University of Technology
Elsevier B.V
2019
Abstract
Application of corrosion resistant coatings is one of the most widely used means of protecting steel. Zinc coated (galvanize) steel, is well known for galvanic protection of steel substrates and nowadays, particular attention has been paid to the coupling of graphene oxide (GO) with metallic materials, in order to lessen corrosion rate. In this research, an isopropanol supercritical reducing environment prepared to make zinc ions bond directly with graphene oxides, to form a button shape hybrids of ZnO-Graphene (ZnOG). The hybridized bonding between zinc and graphene oxide is confirmed by Fourier Transform Infra-Red analysis. And the morphology revealed, using a Field Emission Scanning...