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Simulation of InGaN-based near-ultraviolet/visible dual-band photodetector
, Article Optical and Quantum Electronics ; Volume 48, Issue 1 , 2016 , Pages 1-11 ; 03068919 (ISSN) ; Hemmat, Z ; Sharif University of Technology
Springer New York LLC
2016
Abstract
In this paper, we report on 2D numerical simulation of spectral response for InGaN dual-band photodetector operating at near ultraviolet and visible wavelengths. The back-to-back p–i–n/n–i–p integrated structure enables independent and simultaneous detection of two bands under back-side illumination. The effect of indium content and absorption layer thickness of the two sub-detectors on external quantum efficiency and optical crosstalk between two sub-detectors have been investigated. The optimum values for indium content and thickness of absorption layer in sub-detectors are determined
Plasmonic enhancement of photocurrent generation in two-dimensional heterostructure of WSe2/MoS2
, Article Nanotechnology ; Volume 32, Issue 32 , 2021 ; 09574484 (ISSN) ; Esfandiar, A ; Sharif University of Technology
IOP Publishing Ltd
2021
Abstract
Enhancing the photoresponse of single-layered semiconductor materials is a challenge for high-performance photodetectors due to atomically thickness and limited quantum efficiency of these devices. Band engineering in heterostructure of transition metal chalcogenides (TMDs) can sort out part of this challenge. Here, we address this issue by utilizing the plasmonics phenomenon to enrich the optoelectronics property of the WSe2/MoS2 heterojunction and further enhancement of photoresponse. The introduced approach presents a contamination-free, tunable and efficient way to improve light interactions with heterojunction devices. The results showed a 3600-fold enhancement in photoresponsivity and...
The most optimal barrier height of InGaN light-emitting diodes
, Article Applied Physics A: Materials Science and Processing ; Volume 127, Issue 2 , 2021 ; 09478396 (ISSN) ; Faez, R ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2021
Abstract
In this paper, a novel structure is presented in order to decrease the polarization charges of quantum wells. The main purpose of this design is to make electron and hole wavefunctions closer to each other and to increase overlap integral following an increase of radiative recombination rates and internal quantum efficiency. Furthermore, carriers will be increased and become more balanced and identical which leads to an increase in efficiency of light-emitting diodes. The improvement of radiative recombination rates is studied in new structures. Energy bands diagram, carriers density, current density–voltage, and power density–current density are used to demonstrate the superior performance...
The most optimal barrier height of InGaN light-emitting diodes
, Article Applied Physics A: Materials Science and Processing ; Volume 127, Issue 2 , 2021 ; 09478396 (ISSN) ; Faez, R ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2021
Abstract
In this paper, a novel structure is presented in order to decrease the polarization charges of quantum wells. The main purpose of this design is to make electron and hole wavefunctions closer to each other and to increase overlap integral following an increase of radiative recombination rates and internal quantum efficiency. Furthermore, carriers will be increased and become more balanced and identical which leads to an increase in efficiency of light-emitting diodes. The improvement of radiative recombination rates is studied in new structures. Energy bands diagram, carriers density, current density–voltage, and power density–current density are used to demonstrate the superior performance...
Simulation of deep level traps effects in quantum well transistor laser
, Article Journal of Computational Electronics ; Volume 12, Issue 4 , August , 2013 , Pages 812-815 ; 15698025 (ISSN) ; Faez, R ; Sharif University of Technology
2013
Abstract
In this paper, we present an analytical model to analyze the influence of deep level traps on the static and dynamic responses of transistor laser (TL). Our analyze is based on analytically solving the continuity equation and rate equations including the effect of the deep level trap (DLT), which incorporate the virtual states as a conversion mechanism. The results of simulation show that the main characteristics of laser such as threshold current, quantum efficiency, output power, and modulation bandwidth are affected by total density of traps in the active region
Analysis of deep level trap effects in transistor lasers
, Article Lasers in Engineering ; Volume 25, Issue 5-6 , 2013 , Pages 313-322 ; 08981507 (ISSN) ; Mirmoeini, S ; Faez, R ; Sharif University of Technology
2013
Abstract
In this paper we present an analytical model to analyze the influence of deep level traps on the static and dynamic responses of transistor laser (TL). Our analysis is based on analytically solving the continuity equation and rate equations including the effect of the deep level trap (DLT), which incorporates the virtual states as a conversion mechanism. The results of simulation show that the main characteristics of laser such as threshold current, quantum efficiency, output power, and modulation bandwidth are affected by total density of traps in the active region
Aggregates of plasmonic nanoparticles for broadband light trapping in dye-sensitized solar cells
, Article Journal of Optics (United Kingdom) ; Volume 18, Issue 1 , November , 2015 ; 20408978 (ISSN) ; Dabirian, A ; Danaei, D ; Taghavinia, N ; Sharif University of Technology
Institute of Physics Publishing
2015
Abstract
Metallic nanoparticles (NPs) have not been effective in improving the overall performance of the cells with micrometer-thick absorbing layers mainly due to the parasitic optical dissipation in the metal. Here, using both experiment and theory, we demonstrate that aggregates of metallic NPs enhance the light absorption of dye-sensitized solar cells of a few micrometer-thick light absorbing layers. The composite electrode containing the optimal concentration of 5 wt% Au@SiO2 aggregates shows the enhancement of 80% and 52% in external quantum efficiency and photocurrent density, respectively. The superior performance of the aggregates relative to NP is attributed to their larger scattering...
Effect of Stone-Wales defect on an armchair graphene nanoribbon-based photodetector
, Article Superlattices and Microstructures ; Volume 130 , 2019 , Pages 127-138 ; 07496036 (ISSN) ; Faez, R ; Moravvej Farshi, M. K ; Saghafi, K ; Sharif University of Technology
Academic Press
2019
Abstract
The effect of Stone-Wales (SW) defect on the performance of an armchair graphene nanoribbon (AGNR)-based photodetector is studied. To model the SW defect two new tight-binding (TB) parameters are proposed that provide results that are in good agreement with density functional theory calculations. SW defect is introduced in different locations in the channel of the AGNR detector and the photocurrent, quantum efficiency and responsivity of defected structures are calculated using TB approximation and non-equilibrium Green's function formalism. By inspecting the photo-generated hole density in different points of the channel, the way that photocurrent is affected by SW defect in different...
An investigation into the energy transfer efficiency of a two-pigment photosynthetic system using a macroscopic quantum model
, Article BioSystems ; Volume 197 , 2020 ; Shafiee, A ; Sharif University of Technology
Elsevier Ireland Ltd
2020
Abstract
Despite several different measures of efficiency that are applicable to the photosynthetic systems, a precise degree of efficiency of these systems is not completely determined. Introducing an efficient model for the dynamics of light-harvesting complexes in biological environments is a major purpose in investigating such systems. Here, we investigate the effect of macroscopic quantum behavior of a system of two pigments on the transport phenomena in this system model which interacts with an oscillating environment. We use the second-order perturbation theory to calculate the time-dependent population of excitonic states of a two-dimensional Hamiltonian using a non-master equation approach....
Evaluating Cu2SnS3nanoparticle layers as hole-transporting materials in perovskite solar cells
, Article ACS Applied Energy Materials ; Volume 4, Issue 6 , 2021 , Pages 5560-5573 ; 25740962 (ISSN) ; Mirhosseini, M ; Abdizadeh, K ; Mahdavi, S. M ; Taghavinia, N ; Sharif University of Technology
American Chemical Society
2021
Abstract
We investigate the use of simple nontoxic Cu2SnS3 (CTS) nanoparticles (NPs) as low-cost dopant-free hole-transport materials (HTMs) a substitute for spiro-OMeTAD in an n-i-p mesoscopic architecture of perovskite solar cells (PSCs). Besides, this work confirms the critical role of the crystalline phase of CTS NPs on the performance of the device. Using a facile one-pot heating-up procedure, pure zincblende and wurtzite structures of CTS NPs were obtained by sulfur element and thiourea as the sulfur source, respectively, and were dispersed in chloroform to make very stable nonpolar ink that is compatible with the perovskite. Nanoparticles with the wurtzite crystal phase showed much better...
Room-temperature quantum effect in silicon nanoparticles obtained by low-energy ion implantation and embedded in a nanometer scale capacitor
, Article Applied Physics Letters ; Volume 86, Issue 16 , 2005 , Pages 1-3 ; 00036951 (ISSN) ; Grisolia, J ; Assayag, G. B ; Coffin, H ; Atarodi, S. M ; Claverie, A ; Sharif University of Technology
2005
Abstract
In this article, we present the room-temperature current-voltage characteristics of a nanometer scale (100×100 nm2) metal-oxide-semiconductor capacitor containing few (less than 100) silicon nanoparticles. The layer of silicon nanoparticles is synthesized within the oxide of this capacitor by ultra low-energy ion implantation and annealing. Current fluctuations in the form of discrete current steps and sharp peaks appeared in the static and dynamic I (V) characteristics of the capacitor. These features have been associated to quantized charging and discharging of the nanoparticles and the resulting Coulomb interaction to the tunneling current. © 2005 American Institute of Physics
Calculation of Quantum Transition Probabilities between Codons and Concept of Biological Information
, Ph.D. Dissertation Sharif University of Technology ; Shafiee, Afshin (Supervisor)
Abstract
It has been about a century since the introduction of the theory of quantum mechanics. This theory is a branch of physics that describes the behavior of nature in very small scales and microscopic systems . Since no quantum system is entirely isolated from its surroundings , it is necessary to study their interactions with the environment to understand them accurately. The theory of open quantum systems provides the theoretical and conceptual framework needed to consider these interactions. Then using the appropriate quantum operations , the evolution of the combined system can be investigated. Moreover , considering the environmental effects, some quantum features such as dissipation...
Morphological dependence of light backscattering from metallic back reflector films: Application in dye-sensitized solar cells
, Article Physica Status Solidi (A) Applications and Materials Science ; Volume 212, Issue 4 , January , 2015 , Pages 785-790 ; 18626300 (ISSN) ; Ghazyani, N ; Taghavinia, N ; Sharif University of Technology
Wiley-VCH Verlag
2015
Abstract
Conventionally, a film of TiO2 particles of 300 nm size is employed in Dye-sensitized solar cells (DSCs) as the back reflector film to enhance the light harvesting. Perfect reflectance of silver in visible and near infrared motivates to investigate its potential as the material for the light back reflector film in DSCs. In this study, light back reflector films consisting of 300 nm-sized silver particles, as well as vacuum evaporated silver flat film, were fabricated and compared to 300 nm-sized rutile-type TiO2 particulate reflector film to study their optical aspects. Conventional TiO2 rutile-type particulate film demonstrates slightly lower performance...
Sequential deposition as a route for efficient counter electrodes in quantum dot sensitized solar cells
, Article RSC Advances ; Volume 5, Issue 57 , May , 2015 , Pages 45592-45598 ; 20462069 (ISSN) ; Samadpour, M ; Taghavinia, N ; Sharif University of Technology
Royal Society of Chemistry
2015
Abstract
In this paper, we introduce the sequential deposition method for enhancing the performance of nanocomposite counter electrodes (CEs) in quantum dot sensitized solar cells (QDSCs). Here, various CEs are made by the deposition of CuS, PbS, and CuS/PbS nanocomposite layers on an FTO (fluorine doped tin oxide) coated glass substrate by a simple successive ionic layer adsorption and reaction (SILAR) method. The result indicates that the efficiency of the cells with CuS/PbS CEs is enhanced by 2.65% compared with the bare CuS (0.99%) or PbS (1.47%) CEs. Also, no considerable improvement is observed for PbS/CuS CEs (1.09%), which indicates that the order of PbS and CuS deposition is critical for...
A novel thermo-photovoltaic cell with quantum-well for high open circuit voltage
, Article Superlattices and Microstructures ; Volume 83 , July , 2015 , Pages 61-70 ; 07496036 (ISSN) ; Faez, R ; Akbari Eshkalak, M ; Sharif University of Technology
Academic Press
2015
Abstract
Abstract We design a thermo-photovoltaic Tandem cell which produces high open circuit voltage (Voc) that causes to increase efficiency (η). The currently used materials (AlAsSb-InGaSb/InAsSb) have thermo-photovoltaic (TPV) property which can be a p-n junction of a solar cell, but they have low bandgap energy which is the reason for lower open circuit voltage. In this paper, in the bottom cell of the Tandem, there is 30 quantum wells which increase absorption coefficients and quantum efficiency (QE) that causes to increase current. By increasing the current of the bottom cell, the top cell thickness must be increased because the top cell and the bottom cell should have the same current. In...
Performance assessment of thermophotovoltaic application in steel industry
, Article Solar Energy Materials and Solar Cells ; Volume 157 , 2016 , Pages 55-64 ; 09270248 (ISSN) ; Sharif University of Technology
Elsevier
2016
Abstract
The potential for using Thermophotovoltaic (1TPV) generators as an alternative for recovering energy losses in steel production industry is assessed. A mathematical model for the assessment of the performance of TPV application in the iron and steel industry has been developed. In order to support the mathematical model, a sample TPV apparatus in laboratory scale based on an IR emitter has been designed and assembled. The key modeling parameters of TPV generator include: the open circuit voltage, the short circuit current density and fill factor of the TPV cell. These parameters have been considered in the model as functions of several variables such as: the emitter (hot steel slab)...
Mechanochemical green synthesis of exfoliated edge-functionalized boron nitride quantum dots: application to vitamin c sensing through hybridization with gold electrodes
, Article ACS Applied Materials and Interfaces ; Volume 10, Issue 34 , 2018 , Pages 28819-28827 ; 19448244 (ISSN) ; Hatamie, A ; Ghanbari, H ; Simchi, A ; Sharif University of Technology
American Chemical Society
2018
Abstract
Two-dimensional boron nitride quantum dots (2D BNQDs) with excellent chemical stability, high photoluminescence efficiency, and low toxicity are a new class of advanced materials for biosensing and bioimaging applications. To overcome the current challenge about the lack of facile, scalable, and reproducible synthesis approach of BNQDs, we introduce a green and facile approach based on mechanochemical exfoliation of bulk h-BN particles in ethanol. Few-layered hydroxylated-functionalized QDs with a thickness of 1-2 nm and a lateral dimension of 2-6 nm have been prepared. The synthesized nanocrystals exhibit a strong fluorescence emission at 407 and 425 nm with a quantum efficiency of ∼6.2%....
Quantum well design and diffraction efficiency of quantum well light emitting diode
, Article Photonic and Phononic Crystal Materials and Devices IX, San Jose, CA, 27 January 2009 through 29 January 2009 ; Volume 7223 , 2009 ; 0277786X (ISSN) ; Eftekharian, A ; Sodagar, M ; Khorasani, S ; Adibi, A ; Sharif University of Technology
2009
Abstract
In this work, a GaN-based quantum well LED is theoretically analyzed in a multi-layer structure composed of a quantum well embedded in a waveguide core surrounded by photonic crystal slab and a sapphire substrate. The electromagnetic eigenmodes are obtained throughout above structure via revised plane wave-scattering matrix method. The omnidirectional transmission and reflection are investigated for both TE and TM polarizations from diffraction channels in Ewald construction. Then, we introduced angular power density and calculated radiative modes extraction efficiency. All structural parameters, such as lattice geometry, lattice constant, photonic crystal thickness and filling factor, are...
High-Photoresponsive backward diode by two-dimensional SnS2/Silicon heterostructure
, Article ACS Photonics ; Volume 6, Issue 3 , 2019 , Pages 728-734 ; 23304022 (ISSN) ; Esfandiar, A ; Iraji Zad, A ; Hosseini Shokouh, S. H ; Mahdavi, S. M ; Sharif University of Technology
American Chemical Society
2019
Abstract
Two-dimensional semiconductor materials can be combined with conventional silicon-based technology and sort out part of the future challenges in semiconductor technologies due to their novel electrical and optical properties. Here, we exploit the optoelectronics property of the silicon/SnS2 heterojunction and present a new class of backward diodes using a straightforward fabrication method. The results indicate an efficient device with fast photoresponse time (5-10 μs), high photoresponsivity (3740 AW-1), and high quantum efficiency (490%). We discuss device behavior by considering the band-to-band tunneling model and band bending characteristics of the heterostructure. This device structure...
Development of a triple-cation Ruddlesden–Popper perovskite structure with various morphologies for solar cell applications
, Article Journal of Materials Science: Materials in Electronics ; Volume 31, Issue 4 , January , 2020 , Pages 2766-2776 ; Bakhshayesh, A. M ; Khosroshahi, R ; Taghavinia, N ; Abdizadeh, H ; Sharif University of Technology
Springer
2020
Abstract
The present research sheds new light on the development of a triple-cation quasi-two-dimensional (2D) perovskite family with the general formula of (S1−xS′x)2[Cs0.05(FA1−xMAx)0.95]3Pb4(I1−xBrx)13, in which two spacers, namely 5-ammonium valeric acid iodide (S) and tetra-n-octylammonium bromide (S′) were simultaneously incorporated. Morphology, crystal structure, optical properties, photovoltaic performance, and internal resistances of such compound were systemically studied in comparison with an analogous single-cation 2D counterpart (i.e. (S)2(FA)3Pb4I13) as a reference. X-ray diffraction set forth that the films deposited based upon these compounds had a 2D perovskite crystal structure...