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    Triple-tunnel junction single electron transistor (TTJ-SET)

    , Article Modern Physics Letters B ; Volume 25, Issue 17 , 2011 , Pages 1487-1501 ; 02179849 (ISSN) Shahhoseini, A ; Saghafi, K ; Moravvej Farshi, M. K ; Faez, R ; Sharif University of Technology
    We propose a triple-tunnel junction single electron transistor (TTJ-SET). The proposed structure consists of a metallic quantum-dot island that is capacitive coupled to a gate contact and surrounded by three tunnel junctions. To the best of our knowledge, this is the first instance of introducing this new structure that is suitable for both digital and analog applications. I-V D characteristics of the proposed TTJ-SET, simulated by a HSPICE macro model for various gate voltages, are in excellent agreement with those obtained by SIMON, which is a Monte-Carlo based simulator. We show how one can design a digital inverter by using a single TTJ-SET. We also show that, under suitable conditions,... 

    Low-frequency Model for Long-channel Monolayer Transistors

    , Ph.D. Dissertation Sharif University of Technology Omdeh Ghiasi, Hesam (Author) ; Safarian, Amin Ghasem (Supervisor) ; Pourfath, Mahdi (Co-Supervisor)
    Transistors’ miniaturization and advent of short-channel effects causes searching for another devices with least adverse characteristics in short channels. Among all the considered devices, monolayer transistors attracted the attention. Although most of the papers in literature focused on the physical phenomenon of the device, circuit design of these transistors have been overlooked. Most of the papers related to monolayer transistors did not explain the design methodology of their circuits and they confined their work just to the report of the circuits constructed with 2D-based transistors. In order to take advantage of 2D materials in electronic circuits, simple modelling for... 

    Transistor Based on Graphane

    , M.Sc. Thesis Sharif University of Technology Babaee Touski, Shoeib (Author) ; Khorasani, Sina (Supervisor)
    In the recent years, field effect transistor has been made by using graphane. But there has not been any study about bipolar transistor. Bipolar transistor can’t be constructed using graphene due to the fact that its band gap is zero. So in this thesis, in an attempt to remove this difficulty, the bipolar transistor made using graphane has been investigated and their property has been compared to those of three dimensional silicon transistors.
    At the beginning of the thesis, we will have a review of graphane diode and will consider the procedure for evaluating its current which would be the report of what has been done sofar. After that we made graphane transistor using graphane diode... 

    A UHF micro-power CMOS rectifier using a novel diode connected CMOS transistor for micro-sensor and RFID applications

    , Article International Conference on Electronic Devices, Systems, and Applications ; 2012 , Pages 234-238 ; 21592047 (ISSN) ; 9781467321631 (ISBN) Shokrani, M. R ; Hamidon, M. N ; Khoddam, M ; Najafi, V ; Sharif University of Technology
    The design strategy and efficiency optimization of UHF micro-power rectifiers using a novel diode connected MOS transistor is presented. The proposed diode connected MOS transistor uses a new bulk connection which leads to reduce the threshold voltage and leakage current in compare to conventional diode connected transistors. Using the proposed diode in typical rectifiers makes a significant improvement in output voltage and current therefore the efficiency is increased comparing to the same rectifier architectures using conventional diodes. Also a design procedure for efficiency optimization is presented and a superposition method is used to optimize the performance of multiple output... 

    GNRFET with superlattice source, channel, and drain: SLSCD-GNRFET

    , Article Physica E: Low-Dimensional Systems and Nanostructures ; Volume 131 , 2021 ; 13869477 (ISSN) Behtoee, B ; Faez, R ; Shahhoseini, A ; Moravvej Farshi, M. K ; Sharif University of Technology
    Elsevier B.V  2021
    We are proposing a next-generation graphene nanoribbon field-effect transistor (GNRFET) with superlattice source, channel, and drain (SLSCD-GNRFET), with significantly improved switching performance. The presence of superlattice in each region is for energy filtering. The simulation results indicate that the addition of an appropriate superlattice in the channel region, it reduces the subthreshold swing. Also, using proper superlattice in the drain region leads to an increase of more than a decade in the ION/IOFF ratio by intensely reducing the OFF-current. These improvements make the proposed transistor potentially suitable for the next-generation logical digital applications. Comparison of... 

    New integrated optical memory based on the plasma wave modulator/switch

    , Article Integrated Optics Devices V, San Jose, CA, 23 January 2001 through 25 January 2001 ; Volume 4277 , 2001 , Pages 311-314 ; 0277786X (ISSN) Khorasani, S ; Nojeh, A ; Rashidian, B ; SPIE ; Sharif University of Technology
    The feasibility of an integrated optical memory is explored. This memory cell is based on the plasma wave modulator/switch1, which has a horizontal layered structure. A transverse voltage maintains a bias for the structure and can be used for electrical write cycle. The cell content is then read by a propagating guided optical wave across the structure. It is also possible to apply full optical read/write/clear cycles as discussed. The read cycle can be either destructive or nondestructive, depending on the wavelength. A modification of this device may be considered as an opto-transistor, in which an optical signal controls the flow of another optical beam  

    An investigation of ZGNR-based transistors

    , Article 2011 International Semiconductor Device Research Symposium, ISDRS 2011, 7 December 2011 through 9 December 2011 ; December , 2011 , Page(s): 1 - 2 ; 9781457717550 (ISBN) Karamitaheri, H ; Pourfath, M ; Faez, R ; Kosina, H ; Sharif University of Technology
    Graphene, a recently discovered form of carbon, has received much attention for possible applications in nanoelectronics, due to its excellent carrier transport properties [1]. Graphene nanoribbons (GNRs) are thin strips of graphene, where the electronic properties depend on the chirality of the edge and the width of the ribbon. Zigzag GNRs (ZGNRs) show metalic behavior, whereas armchair GNRs (AGNRs) are semiconductors and their band-gap is inversely proportional to their width [2]. Therefore, narrow AGNRs have been recently suggested as a material for transistor channels. However, line edge roughness and substrate impurities can significantly degrade the ballistic transport in AGNRs,... 

    Authors reply to comments on investigation of a class-j mode PA in presence of a second-harmonic voltage at the gate node of the transistor

    , Article IEEE Transactions on Microwave Theory and Techniques ; Volume 66, Issue 7 , 2018 , Pages 3344-3344 ; 00189480 (ISSN) Alizadeh, A ; Medi, A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2018

    Investigating different circuit styles for digital circuits using organic transistors

    , Article 2007 International Symposium on Integrated Circuits, ISIC, Singapore, 26 September 2007 through 28 September 2007 ; 2007 , Pages 5-8 ; 1424407974 (ISBN); 9781424407972 (ISBN) Zamanlooy, B ; Ayatollahi, A ; Fakhraie, S. M ; Chahardori, M ; Sharif University of Technology
    In search of low cost and flexible substrates organic transistors have been suggested as an alternate to silicon transistors. Level 1 model extraction, investigating different circuit styles and proposing two new circuit styles for organic integrated circuits is done in this paper. First, level 1 model of organic transistor is found using ID-VDS characteristics of transistors reported by [9]. After that different design styles used in CMOS digital integrated circuits are reviewed and the functionality of these styles for organic integrated circuits is investigated. Two new circuit styles have been proposed in this section which have better performance for organic circuits comparing with... 

    Numerical simulation of vertical tunneling transistor with bilayer graphene as source and drain regions

    , Article Physica Status Solidi (A) Applications and Materials Science ; Volume 214, Issue 10 , 2017 ; 18626300 (ISSN) Horri, A ; Faez, R ; Darvish, G ; Sharif University of Technology
    In this paper, the electrical characteristics of vertical tunneling bilayer graphene field effect transistor (VTBGFET) are theoretically investigated. We evaluate the device behavior using nonequilibrium Green's function (NEGF) formalism combined with an atomistic tight binding model. By using this method, we extract the most significant figures of merit such as ON/OFF current ratio, subthreshold swing, and intrinsic gate-delay time. The results indicate that using a bilayer graphene instead of a monolayer graphene as the base material for the source and drain regions leads to a larger ON/OFF current ratio due to the presence of an energy bandgap in biased bilayer graphene. Also, the... 

    Using superlattice structure in the source of GNRFET to improve its switching performance

    , Article IEEE Transactions on Electron Devices ; Volume 67, Issue 3 , 2020 , Pages 1334-1339 Behtoee, B ; Faez, R ; Shahhoseini, A ; Moravvej Farshi, M. K ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2020
    Our aim is to improve the switching performance of the graphene nanoribbon field-effect transistors (GNRFETs), exploiting the concept of energy filtering. Within the proposed scheme, a superlattice (SL) structure is used in the source of the transistor for filtering high-energy electron tail by engineering the density of states (DOS). According to simulation results, this can significantly decrease the OFF-current and the subthreshold swing (SS). A comparison of the proposed device with a conventional GNRFET and a graphene nanoribbon (GNR) tunneling field-effect transistor (GNRTFET) demonstrates a significant improvement. Therefore, a typical SL-GNRFET can reduce the average and the minimum... 

    Design guidelines for leakage control transistor

    , Article Conference Proceedings - 2nd Annual IEEE Northeast Workshop on Circuits and Systems, NEWCAS 2004, Montreal, Que., 20 June 2004 through 23 June 2004 ; 2004 , Pages 209-211 ; 0780383222 (ISBN) Farbiz, F ; Emadi, M ; Foruzandeh, B ; Sharif University of Technology
    This paper investigates the effects of transistor sizing of the sleep transistor on the power consumption and speed. A method is proposed to handle the power-delay trade off and a new transistor arrangement is proposed. Simulations show how much is the appropriate size of sleep transistor respect to the gate size  

    Wide-band high-efficiency Ku-band power amplifier

    , Article IET Circuits, Devices and Systems ; Vol. 8, issue. 6 , December , 2014 , p. 583-592 ; 1751858X Yousefi, A ; Medi, A ; Sharif University of Technology
    A 37 dBm power amplifier (PA) is designed on a 0.25 μm optical T-gate pseudomorphic high electron mobility transistor (pHEMT) technology. The design of this two-stage PA along with a step-by-step design procedure is presented in this paper. This methodology can be used for design of PA in different technologies and frequencies. The PA delivers 5 W output power over the frequency band of 13-19 GHz. It shows average power-added efficiency of 37% and large signal gain of 15 dB in measurements which is consistent with simulation results. The output power and efficiency of the realised amplifier reach maximums of 37.6 dBm and 45%, respectively. Considering output power, bandwidth, chip area and... 

    Large signal analysis of double quantum well transistor laser

    , Article Optical and Quantum Electronics ; Volume 45, Issue 5 , 2013 , Pages 389-399 ; 03068919 (ISSN) Horri, A ; Faez, R ; Sharif University of Technology
    In this paper, we present an analytical model for the large-signal analysis of the double quantum well (DQW) transistor laser. Our model is based on solving the continuity equation and the rate equations which incorporate the virtual states as a conversion mechanism. By using the presented model, effects of barrier width on DQW transistor laser static and dynamic performances are investigated. Also the static and dynamic responses of DQW transistor lasers are compared with single quantum well ones. Simulation results are in agreement with the numerical and experimental results reported by other researchers  

    Modeling of a vertical tunneling transistor based on Gr-hBN- χ 3borophene heterostructure

    , Article Journal of Applied Physics ; Volume 132, Issue 3 , 2022 ; 00218979 (ISSN) Abbasi, R ; Faez, R ; Horri, A ; Moravvej Farshi, M. K ; Sharif University of Technology
    American Institute of Physics Inc  2022
    We present a computational study on the electrical behavior of the field-effect transistor based on vertical graphene-hBN- χ 3 borophene heterostructure and vertical graphene nanoribbon-hBN- χ 3 borophene nanoribbon heterostructure. We use nonequilibrium the Green function formalism along with an atomistic tight-binding (TB) model. The TB parameters are calculated by fitting tight-binding band structure and first-principle results. Also, electrical characteristics of the device, such as ION/IOFF ratio, subthreshold swing, and intrinsic gate-delay time, are investigated. We show that the increase of the hBN layer number decreases subthreshold swing and degrades the intrinsic gate-delay time.... 

    Ferromagnetic Single Electron Transistor

    , M.Sc. Thesis Sharif University of Technology Asgari, Somaieh (Author) ; Faez, Rahim (Supervisor)
    This thesis completely introduses ferromagnetic single electron transistor while that identifies the application and types of the transistor.Master equation is used for simulationing of the transistor. This simulation is divided to two general sections.In the first section proposed thermal equilibrium the normal island and The two spin subsystems , however, are in thermal equilibrium and quantized nature of energy spectrum of a small central electrode and fluctuations in the spin accumulation were ignored , however, we simplify the problem and assume that the charging energy are independent of the electron distribution, and number of electrons in the normal island. ،hat tunnel rates can be... 

    Using level restoring method for dual supply voltage

    , Article 19th International Conference on VLSI Design held jointly with 5th International Conference on Embedded Systems Design, Hyderabad, 3 January 2006 through 7 January 2006 ; Volume 2006 , 2006 , Pages 601-605 ; 10639667 (ISSN) ; 0769525024 (ISBN); 9780769525020 (ISBN) Sadeghi, K ; Emadi, M ; Farbiz, F ; Sharif University of Technology
    A new level converter for use in dual voltage SOI digital circuits is presented. This technique uses the idea of keeper transistors, and consumes less power compared to the traditional methods. The effects of load capacitance on the circuit are studied by extensive simulations. © 2006 IEEE  

    The Fabrication and Characterization of Graphene by Mechanical Exfoliation Method and a Review on Graphene Field Effect Transistors

    , M.Sc. Thesis Sharif University of Technology Rostami Osanloo, Mehrdad (Author) ; Akhavan, Omid (Supervisor)
    Graphene is a semiconductor with zero band gap. Due to electron ballistic transportation and having a single atom thickness of graphene, it is counted as an ideal material in Nano-electronic industry and essential candidate for fabrication of next generation of transistors. The Fermi level in graphene is located between Conduction and valance bands in a Dirac point. Due to low resistance, graphene has a substantial sensitivity near the Dirac point to local carrier density changes. This feature makes delicate detection of electromagnetic waves and gas sensing by graphene field effect transistors (GFETs). In this thesis, fabrication and characterization of graphene field effect transistor on... 

    Joint mapping of mobility and trap density in colloidal quantum dot solids [electronic resource]

    , Article Journal of ACS nano ; 2013, Vol.7, No. 7, P.5757-5762 Stadler, Philipp ; Sutherland, Brandon R ; Ren, Yuan ; Ning, Zhijun ; Simchi, A. (Arash) ; Thon, Susanna M ; Hoogland, Sjoerd ; Sargent, Edward H ; Sharif University of Technology
    Field-effect transistors have been widely used to study electronic transport and doping in colloidal quantum dot solids to great effect. However, the full power of these devices to elucidate the electronic structure of materials has yet to be harnessed. Here, we deploy nanodielectric field-effect transistors to map the energy landscape within the band gap of a colloidal quantum dot solid. We exploit the self-limiting nature of the potentiostatic anodization growth mode to produce the thinnest usable gate dielectric, subject to our voltage breakdown requirements defined by the Fermi sweep range of interest. Lead sulfide colloidal quantum dots are applied as the active region and are treated... 

    Analysis of parametric oscillations in high power amplifiers

    , Article Scientia Iranica ; Volume 20, Issue 6 , 2013 , Pages 2084-2092 ; 10263098 (ISSN) Nikandish, G ; Yousefi, A ; Mohammadi, E ; Babakrpour, E ; Medi, A ; Sharif University of Technology
    Sharif University of Technology  2013
    A large-signal analysis of sub-harmonic parametric oscillations in Power Amplifiers (PAs) is presented in this paper. Simplified models for current-voltage and channel charge characteristics of short-channel pseudomorphic High Electron Mobility Transistors (pHEMTs) are adopted to investigate the effects of the device transconductance and gate-source capacitance nonlinearities on the amplifier stability. A 5-W Ku-band PA is designed to demonstrate the application of the presented analysis. MMIC PA is implemented in a 0.25-μm GaAs pHEMT process. According to the measurements, the PA provides 37.5 dBm (5.6 W) of output power, 36% of Power Added Efficiency (PAE), and small-signal gain of 18 dB...