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Improvement in IBC-silicon solar cell performance by insertion of highly doped crystalline layer at heterojunction interfaces

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Chinese Physics B 2017年第10期26卷 508-514页

作者： Hadi Bashiri mohammad azim karami Shahramm mohammadnejad School of Electrical Engineering Iran University of Science &Technology (IUST)

By inserting a thin highly doped crystalline silicon layer between the base region and amorphous silicon layer in an interdigitated back-contact （IBC） silicon solar cell, a new passivation layer is investigated. The passivation layer performance is characterized by numerical simulations. Moreover, the dependence of the output parameters of the solar cell on the additional layer parameters （doping concentration and thickness） is studied. By optimizing the additional passivation layer in terms of doping concentration and thickness, the power conversion efficiency could be improved by a factor of 2.5%, open circuit voltage is increased by 30 mV and the fill factor of the solar cell by 7.4%. The performance enhancement is achieved due to the decrease of recombination rate, a decrease in solar cell resistivity and improvement of field effect passivation at heterojunction interface. The above-mentioned results are compared with reported results of the same conventional interdigitated back-contact silicon solar cell structure. Furthermore, the effect of a-Si：H/c-Si interface defect density on IBC silicon solar cell parameters with a new passivation layer is studied. The additional passivation layer also reduces the sensitivity of output parameter of solar cell to interface defect density.

关键词： IBC silicon solar cells interface layer recombination interface defect density

Ultrasensitive plasmonic sensor based on MDM waveguide containing Persian Orsi window cavities for refractive index and blood plasma sensing

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Optoelectronics Letters 2024年第7期20卷 406-411页

作者： mohammad Ghanavati mohammad azim karami School of Electrical Engineering Iran University of Science and TechnologyTehran 16846-13114Iran12

We developed a plasmonic refractive index(RI)with a metal-dielectric-metal(MDM)structure that utilizes two Persian Orsi windows-like separated cavities with a high figure of merit(FoM)and *** simulated and optimized Ag-air-Ag MDM sensor for surface plasmon resonance(SPR)offers high RI sensitivity(SRI)and the ability to detect blood plasma concentration(BPC).The results verified that structural parameters have an effect on SRI,full width at half maximum(FWHM),FoM,sensitivity of blood plasma(S_(p))for right and left peaks,whose values are 1345.45 nm·RIU^(−1),32 nm,42.04 RIU^(−1),0.26 and 0.19 nm·L·g^(-1),*** proposed design opens a new horizon in sensor development.

关键词： index utilize MDM

Tunneling in submicron CMOS single-photon avalanche diodes

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Chinese Optics Letters 2014年第1期12卷 66-68页

作者： mohammad azim karami Armin Amiri-Sani mohammad Hamzeh Ghormishi Department of Electrical Engineering Iran University of Science and Technology

Tunneling is studied in two main single-photon avalanche diode （SPAD） topologies, which are r^-tub guard ring （NTGR） and p-tub guard ring （PTGR）. Device sinmlation, I - V measurements, and dark count calculations and measurements demonstrate that tunneling is the main source of noise in NTGR, but it is less dominant in PTGR SPADs. All structures are characterized with respect to dark noise, photon detection probability, tinting jitter, afterpulsing probability, and breakdown voltage. Noise performmme is disturbed because of tunneling, whereas jitter performance is disturbed because of the short diffusion time of photo-generated minority carriers in NTGR SPADs. The maximum photon detection probability is enhanced because of an improvement in absorption thickness.

关键词： Tunneling in submicron CMOS single-photon avalanche diodes CMOS SPAD

A Novel Adjustable Plasmonic Filter Realization by Split Mode Ring Resonators

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Journal of Electromagnetic Analysis and Applications 2013年第12期5卷 405-414页

作者： Mohsen Janipour mohammad azim karami Rahman Sofiani Farrokh Hodjat Kashani Department of Electrical Engineering Iran University of Science and Technology Tehran Iran.

A novel nanoscale plasmonic filter consisting of two coupled metal-insulator-metal (MIM) waveguides is introduced. The new structure functionality is verified by numerical simulations in different configurations of the filter. The impedance variation characteristic named as split mode ring resonancy is achieved by partially narrowing or expanding the waveguide diameter. The main parameters of the filter are evaluated by using the parameters of an implemented type of ring resonator. Moreover, modal analysis for Surface Plasmon Polariton (SPP) propagation is performed while changing the main spatial parameters of the device.

关键词： Plasmonic Filter Ring Resonator MIM Waveguide

Effect of Residual Charge Carrier on the Performance of a Graphene Field Effect Transistor

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Chinese Physics Letters 2016年第1期33卷 113-117页

作者： Sedighe Salimian mohammad Esmaeil azim Araghi Faculty of Physics Kharazmi University

The temperature-dependent effect of residual charge carrier （no）, at the Dirac point, on mobility is studied. We fabricate and characterize a graphene field effect transistor （GFET） using 7nm TiO2 as the top-gate dielectric. The temperature-dependent gate voltage-drain current and room temperature gate capacitance are measured to extract the carrier mobility and to estimate the quantum capacitance of the GFET. The device shows the mobility value of gOO cm^2 /V.s at room temperature and it decreases to 45 cm^2 /V.s for 20 K due to the increase of n0. These results indicate that the phonon scattering is not the dominant process for the unevenness dielectric layer while the coulomb scattering by charged impurities degrades the device characteristically at low temperature.

关键词： of it by Effect of Residual Charge Carrier on the Performance of a Graphene Field Effect Transistor on is VTG high for into that

Evaluation of the stability of terraced slopes in clayey gravel soil using a novel numerical technique

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Frontiers of Structural and Civil Engineering 2023年第5期17卷 796-811页

作者： Mehrdad karami mohammad NAZARI-SHARABIAN James BRISTOW Moses KARAKOUZIAN Department of Civil and Environmental Engineering and Construction University of NevadaLas VegasLas VegasNV 89154USA Department of Mathematics Engineeringand Computer ScienceWest Virginia State UniversityInstituteWV 25112USA R&D Department Universal Engineering SciencesLas VegasNV 89118USA

Conventional geotechnical software limits the use of the strength reduction method(SRM)based on the Mohr–Coulomb failure criterion to analyze the slope safety factor(SF).The use of this constitutive model is impractical for predicting the behavior of all soil *** the present study,an innovative numerical technique based on SRM was developed to determine SF using the finite element method and considering the extended Cam–clay constitutive model for clayey gravel soil as opposed to the Mohr–Coulomb *** this regard,a novel user subroutine code was employed in ABAQUS to reduce the stabilizing forces to determine the failure surfaces and resist and drive shear stresses on a *** validating the proposed technique,it was employed to investigate the performance of terraced slopes in the context of a case *** impacts of geometric parameters and different water table elevations on the SF were *** results indicated that an increase in the upper and lower slope heights led to a decrease in SF,and a slight increase in the horizontal offset led to an increase in the ***,when the water table elevation was lower than the toe of the terraced slope,the SF increased because of the increase in the uplift force as a resistant component.

关键词： terraced slope safety factor finite element method ABAQUS extended Camclay

Performance of fixed beam without interacting bars

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Frontiers of Structural and Civil Engineering 2020年第5期14卷 1180-1195页

作者： Aydin SHISHEGARAN Behnam karami Timon RABCZUK Arshia SHISHEGARAN mohammad Ali NAGHSH Mohammreza mohammad KHANI School of Civil Engineering Iran University of Science and TechnologyTehran 13114-16846Iran International Institute of Earthquake Engineering and Seismology Tehran 19537-14453Iran Division of Computational Mechanics Ton Duc Thang UniversityHo Chi Minh CityVietnam Faculty of Civil Engineering Ton Duc Thang UniversityHo Chi Minh CityVietnam School of Civil engineering Islamic Azad UniversityTehran ***Iran School of Civil Engineering Isfahan University of TechnologyIsfahan ***Iran

Increasing the bending capacity of reinforced concrete(RC)elements is one of important topics in structure *** goal of this study is to develop a transferred stress system(TSS)on longitudinal reinforcement bars for increasing the bending capacity of RC *** study is divided into two parts,i.e.,experimental tests and nonlinear FE *** experiments were carried out to determine the load-deflection curves and crack patterns of the ordinary and TSS fixed *** FE models were developed for simulating the fixed *** obtained load-deflection results and the observed cracks from the FE analysis and experimental tests are compared to evaluate the validation of the FE nonlinear *** on the validated FE models,the stress distribution on the ordinary and TSS bars were *** found the load carrying capacity and ductility of TSS fixed beam are 29.39%and 23.69%higher compared to those of the ordinary fixed *** crack expansion occurs on the ordinary fixed beam,although there are several crack openings at mid-span of the TSS fixed *** crack distribution was changed in the TSS fixed *** TSS fixed beam is proposed to employ in RC frame instead of ordinary RC beam for improving the performance of RC frame.

关键词： transferred stress system bending capacity crack opening crack propagation FE nonlinear model stress distribution

Experimental investigation and flow analysis of clear-water scour around pier and abutment in proximity

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Water Science and Engineering 2023年第1期16卷 94-105页

作者： mohammad Saeed Fakhimjoo Abdollah Ardeshir Kourosh Behzadian Hojat karami Department of Civil and Environmental Engineering Amirkabir University of TechnologyTehran 15875-4413Iran School of Computing and Engineering University of West LondonLondon W55RFUK Department of Civil Engineering Semnan UniversitySemnan 35131-19111Iran

Local scour around bridge piers and abutments is one of the most significant causes of bridge *** a plethora of studies on scour around individual bridge piers or abutments,few studies have focused on the joint impact of a pier and an abutment in proximity to one another on *** study conducted laboratory experiments and flow analyses to examine the interaction of piers and abutments and their effect on clear-water *** experiments were conducted in a rectangular laboratory *** included 18 main tests(with a combination of different types of piers and abutments)and five control tests(with individual piers or abutments).Three pier types(a rectangular pier with a rounded edge,a group of three cylindrical piers,and a single cylindrical pier)and two abutment types(a wingewall abutment and a semicircular abutment)were *** acoustic Doppler velocimeter was used to measure the three-dimensional flow velocity for analyses of streamline,velocity magnitude,vertical velocity,and bed shear *** results showed that the velocity near the pier and abutment increased by up to 80%.The maximum scour depth around the abutment increased by up to 19%.In contrast,the maximum scour depth around the pier increased significantly by up to l71%.The presence of the pier in the vicinity of the abutment led to an increase in the scour hole volume by up to 87%relative to the case with a solitary *** equations were also derived to accurately estimate the maximum scour depth at the pier adjacent to the abutment.

关键词： Abutment ADV Bridge scour Laboratory experiment Maximum scour depth Pier

Simulation of flow pattern at rectangular lateral intake with different dike and submerged vane scenarios

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Water Science and Engineering 2017年第3期10卷 246-255页

作者： Hojat karami Saeed Farzin mohammad Tavakol Sadrabadi Hasan Moazeni Faculty of Civil Engineering Semnan University School of Water Sciences Engineering Shahid Chamran University of Ahvaz

A comprehensive understanding of the sediment behavior at the entrance of diversion channels requires complete knowledge of threedimensional(3 D) flow behavior around such structures. Dikes and submerged vanes are typical structures used to control sediment entrainment in the diversion channel. In this study, a 3 D computational fluid dynamic(CFD) code was calibrated with experimental data and used to evaluate flow patterns, the diversion ratio of discharge, the strength of secondary flow, and dimensions of the vortex inside the channel in various dike and submerged vane installation scenarios. Results show that the diversion ratio of discharge in the diversion channel is dependent on the width of the flow separation plate in the main channel. A dike perpendicular to the flow with a narrowing ratio of 0.20 doubles the ratio of diverted discharge in addition to reducing suspended sediment input to the basin, compared with a no-dike situation, by creating the outer arch conditions. A further increase in the narrowing ratio decreases the diverted discharge. In addition, increasing the longitudinal distance between consecutive vanes(Ls) increases the velocity gradient between the vanes and leads to a more severe erosion of the bed, near the vanes.

关键词： Three-dimensional simulation Computational fluid dynamics Submerged vanes Dike Side and vortex flow