Search for: field-effect-transistor
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    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... 

    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... 

    Numerical investigation on the temperature dependence of the cylindrical-gate-all-arounD Si-NW-FET

    , Article Modern Physics Letters B ; Volume 25, Issue 29 , 2011 , Pages 2269-2278 ; 02179849 (ISSN) Sedigh Zyiabari, S. A ; Saghafi, K ; Faez, R ; Moravvej-Farshi, M. K ; Sharif University of Technology
    We report the results of our numerical investigation on the temperature dependence of the characteristics of the cylindrical gate-all-around Si nanowire field effect transistor (Si-NW-FET). Assuming the effect of temperature on the energy band structure of Si just like the effect of strain, we simulate the transistor characteristics at various temperatures (50 K ≤ T ≤ 300 K). In this investigation, we demonstrate the temperature dependence of the transistor sub-threshold swing and the threshold voltage are both linear functions of the temperature, represented by 61.5 × (T/300) + 63.4 (mV/decade) and 220140 × (T/300-1) (mV). By calculating the IDS - T characteristics for VDS = 0.4 V and... 

    Extended-gate field-effect transistor based sensor for detection of hyoscine n-butyl bromide in its pharmaceutical formulation

    , Article Analytical and Bioanalytical Electrochemistry ; Volume 12, Issue 2 , 2020 , Pages 238-249 Sheibani, S ; Mirzaie, S. I ; Fardmanesh, M ; Norouzi, P ; Sharif University of Technology
    Center of Excellence in Electrochemistry, Univ. of Tehran  2020
    A novel recognition method for selective determination of the hyoscine N-Butyl bromide (HBB), an antispasmodic agent for smooth muscles, was devised using extended gate field-effect transistor (EG-FET) as transducing unit. For this purpose a PVC membrane, containing hyoscine n-butyl-tetraphenyl borate ion-pair as recognition component, was coated on Ag/AgCl wire, which was connected to the extended metal gate. In optimal conditions, the linear range for HBB was 10-8-10-5 molL−1 with limit of detection 1.7×10-9 molL-1. The proposed sensor was applied in real sample, it showed fast response with high accuracy, and therefore it could be used as HPLC detector in the pharmaceutical samples in... 

    Investigation of Temperature Effect on MOSFET Parameters and Modeling of Carrier Mobility in Temperature Range of 77 - 300K

    , M.Sc. Thesis Sharif University of Technology Seyed Fakhari, Moein (Author) ; Fardmanesh, Mahdi (Supervisor) ; Medi, Ali (Supervisor)
    Temperature reduction from room temperature to liquid nitrogen temperature has a significant effect in improvement of semiconductor devices operation such as field effect transistors. Nowadays cryoelectronics as a considerable branch of electronics is concerned by several groups. In order to optimize the procedure of low temperature IC design and fabrication we investigated the temperature effects on different parameters of MOSFET in this thesis. Several transistors in a variety of channel lengths were fabricated in different technology files. Wide measurement experiments were done on these transistors in order to find their drain current vs. drain to source voltage characteristics. From... 

    DNA-decorated graphene nanomesh for detection of chemical vapors

    , Article Applied Physics Letters ; Volume 103, Issue 18 , 2013 ; 00036951 (ISSN) Esfandiar, A ; Kybert, N. J ; Dattoli, E. N ; Hee Han, G ; Lerner, M. B ; Akhavan, O ; Irajizad, A ; Charlie Johnson, A. T ; Sharif University of Technology
    The promise of graphene for use as a vapor sensor motivated exploration of the vapor responses of graphene nanomesh (GNM) functionalized with single stranded DNA. Devices detected different vapor types, including carboxylic acids, aldehydes, organophosphates, and explosives. As-fabricated GNM field effect transistors (FETs) had larger vapor responses than standard graphene FETs due to the effect of oxidized edges and lattice defects. DNA-GNM devices discriminated between homologous species with detection limits of a few parts per million, with fast response and recovery. Responses varied significantly when the base sequence of the DNA was changed, making the sensor class an intriguing... 

    A seamless-pitched graphene nanoribbon field effect transistor

    , Article Physica E: Low-Dimensional Systems and Nanostructures ; Volume 74 , November , 2015 , Pages 414-420 ; 13869477 (ISSN) Haji Nasiri, S ; Moravvej Farshi, M. K ; Faez, R ; Sharif University of Technology
    Elsevier  2015
    This paper proposes a graphene nanoribbon field effect transistor (GNRFET) consisting of pitched semiconducting GNRs as the channels that are connected to the metallic graphene source/drain in a seamless fashion. We obtained the diagrams for frequency bandwidths, step time responses, and Nyquist stability for the seamless pitched GNRFET (SP-GNRFET) with a channel having 100 pitched GNRs at 10 nm pitch in the common source configuration with various dimensions of the GNRs. The aforementioned diagrams were also obtained for the pitched carbon nanotube field effect transistor (CNTFET) with a channel having 100 pitched CNTs at 10 nm pitch in the common source configuration with various... 

    A 3D analytical modeling of tri-gate tunneling field-effect transistors

    , Article Journal of Computational Electronics ; Volume 15, Issue 3 , 2016 , Pages 820-830 ; 15698025 (ISSN) Marjani, S ; Hosseini, S. E ; Faez, R ; Sharif University of Technology
    Springer New York LLC  2016
    In this paper, a three-dimensional (3D) analytical solution of the electrostatic potential is derived for the tri-gate tunneling field-effect transistors (TG TFETs) based on the perimeter-weighted-sum approach. The model is derived by separating the device into a symmetric and an asymmetric double-gate (DG) TFETs and then solving the 2D Poisson’s equation for these structures. The subthreshold tunneling current expression is extracted by numerical integrating the band-to-band tunneling generation rate over the volume of the device. It is shown that the potential distributions, the electric field profile, and the tunneling current predicted by the analytical model are in close agreement with... 

    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 of Power Amplifier in Ku Band in the Process of GaAs-pHEMT

    , M.Sc. Thesis Sharif University of Technology Yousefi, Alireza (Author) ; Medi, Ali (Supervisor)
    Power amplifiers are used as the last block of transmitters. This block can be categorized as the one of most important part in communication systems. However, in transmitter systems which require high power to create stable link with the receivers, fabrication process like CMOS are unable to provide such level of power. Thus, designers employ another group of integrated circuits which names MMIC that offers this capability to designers. MMIC is the abbreviation of Microwave Integrated Circuit which is implemented in compound substrates like GaAs. Monolithic microwave integrated circuits enable the implementation of amplifiers in small size, large number, with high precision and appropriate... 

    Simulation of HEMT (High Electron mobility Transistor) for Communication Applications

    , M.Sc. Thesis Sharif University of Technology Tahmasebi, Marzie (Author) ; Sarvari, Reza (Supervisor)
    In this thesis, the simulation of HEMT for high frequency applications has been explored. It has been tried to examine the changes such as: gate recess, T-shaped gate, changing the channel length and doping of buffer layer on the performance of the proposed device. Simulation results show that the best way to improve the device performance, in particular its cut-off frequency, is increase in buffer layer doping density. Because it significantly increase the saturation current, electron mobility inside the channel, the transconductance and the cut-off frequency. If we need to lower the noise, the T-shaped gate can also be used. Also, by change in doping of donor layer, amount of 1017 cm-3 is... 

    A Simulation Study of Graphene Nanoribbon Field Effect Transistor

    , M.Sc. Thesis Sharif University of Technology Samadi, Mohsen (Author) ; Faez, Rahim (Supervisor)
    In this thesis, a field effect transistor (FET) using armchair graphene nanoribbon as the channel is simulated, and the effects of changing nanoribbon width and length, as well as adding defects, are also studied. To obtain the Hamiltonian matrix and the energy band structure of graphene nanoribbon, tight binding method is used in which the first and third neighbor approximation is considered. Also, to maximize accuracy, we also considered the edge bond reconstruction. To obtain the transport characteristics of the transistor, such as the transmission coefficient and the density of states (DOS), Poisson and Schrodinger equations are solved self-consistently. We used the nonequilibrium... 

    Simulation and Comparative Study of Tunneling FETs Based on Graphene Nanoribbon and Phosphorene Monolayer

    , M.Sc. Thesis Sharif University of Technology Almasi, Hossein (Author) ; Faez, Rahim (Supervisor)
    In this thesis, we simulate and investigate two transistors which both have tunneling FET (TFET) structure but the channel in the first one is graphene nanoribbon (GNR) and in the second one is a monolayer of phosphorene (PML). To describe the quantum systems of the transistors, we use the tight binding method and its models for the channel materials. In case of the PML TFET, based on the behavior of the phosphorene nanoribbon in different widths, we obtain a proper amount for the width to model the infinite-width channel. To extract the channel quantum transport, the Schrodinger-Poisson equations are self-consistently solved. In the next step, we simulate the GNR TFET and present the... 

    Growth of Two-Dimensional Molybdenum Disulfide Structures for Gas Sensing Application

    , Ph.D. Dissertation Sharif University of Technology Barzegar, Maryam (Author) ; Irajizad, Azam (Supervisor) ; Asgari, Reza (Supervisor)
    Molybdenum disulfide (MoS2) nanoflakes, a two-dimensional crystal with tunable bandgap depends on number of layers, is a promising candidate for future nanoelectronic devices. In the present research, flower shaped MoS2 nanoflakes have been synthesized via hydrothermal method. As part of the research, the growth of triangular MoS2 monolayer up to 10 micrometers has optimized by carring out several chemical vapor deposition experiments with varying deposition parameters. The prepared samples were characterized using optical, scanning electron, and atomic force microscopes, x-ray diffraction analysis, and Raman spectroscopy. Based on the experimental results, the growth mechanism has been... 

    The ITO-capped WO3 nanowires biosensor based on field-effect transistor in label-free protein sensing

    , Article Applied Physics A: Materials Science and Processing ; Volume 123, Issue 5 , 2017 ; 09478396 (ISSN) Shariati, M ; Sharif University of Technology
    Springer Verlag  2017
    The fabrication of ITO-capped WO3 nanowires associated with their bio-sensing properties in field-effect transistor diagnostics basis as a biosensor has been reported. The bio-sensing property for manipulated nanowires elucidated that the grown nanostructures were very sensitive to protein. The ITO-capped WO3 nanowires biosensor showed an intensive bio-sensing activity against reliable protein. Polylysine strongly charged bio-molecule was applied as model system to demonstrate the implementation of materialized biosensor. The employed sensing mechanism was ‘label-free’ and depended on bio-molecule’s intrinsic charge. For nanowires synthesis, the vapor–liquid–solid mechanism was used.... 

    Design of a Low Power and Robust SRAM Cell Based on FinFET

    , M.Sc. Thesis Sharif University of Technology Sayyah Ensan, Sina (Author) ; Hesabi, Shahin (Supervisor) ; Moaiyeri, Mohammad Hossein (Supervisor)
    By scaling the technology node, leakage power and process variations emerge as the two important factors to design a chip. Static power becomes more important when the number of portable devices which spend most of the time in the idle mode is increasing.Process variations lessen performance, reliability and lead to more leakage power. To mitigate these limitations multiple devices have been proposed to displace Bulk MOSFET.Among these devices we can name FinFET and CNTFET transistors. FinFET transistors due to their superior gate control in compare to Bulk MOSFETs transistor have shown lesser short channel effects, more scalability, more I_on to I_off ratio and lesser process variations.... 

    Simulation of a carbon nanotube field effect transistor with two different gate insulators

    , Article Scientia Iranica ; Volume 20, Issue 6 , 2013 , Pages 2332-2340 ; 10263098 (ISSN) Fallah, M ; Faez, R ; Jafari, A. H ; Sharif University of Technology
    Sharif University of Technology  2013
    In this paper, a novel structure for MOSFET like CNTFETs (MOSCNTs) is proposed, combining the advantages of both high and low dielectrics to improve output characteristics. In this structure, the gate dielectric at the drain side is selected from a material with low dielectric constant to form smaller capacitances, while a material with high dielectric constant is selected at the source side to improve on current and reduce leakage current. The new structure is simulated based on the Schrödinger-Poisson formulation. Obtained results show that the proposed configuration has lower off and higher on current in comparison with low-k MOSCNTs. Also, using a two-dimensional model, a wide range of... 

    Improving ION / IOFF and sub-threshold swing in graphene nanoribbon field-effect transistors using single vacancy defects

    , Article Superlattices and Microstructures ; Volume 86 , October , 2015 , Pages 483-492 ; 07496036 (ISSN) Nazari, A ; Faez, R ; Shamloo, H ; Sharif University of Technology
    Academic Press  2015
    Graphene nanoribbon field effect transistors are promising devices for beyond-CMOS nanoelectronics. Graphene is a semiconductor material with zero bandgap and its bandgap must be changed. One of the opening bandgap methods is using graphene nanoribbons. By applying a defect, there is more increase on band gap of monolayer armchair graphene nanoribbon field effect transistor. So, by applying more than one defect, we can reach to much more increase in bandgap of graphene nanoribbon field effect transistors (GNRFET). In this paper, double-gated monolayer armchair graphene nanoribbon field effect transistors (GNRFET) with one single vacancy (1SV) defect (so-called 1SVGNRFET)are simulated and... 

    A silicon doped hafnium oxide ferroelectric p-n-p-n SOI tunneling field-effect transistor with steep subthreshold slope and high switching state current ratio

    , Article AIP Advances ; Volume 6, Issue 9 , 2016 ; 21583226 (ISSN) Marjani, S ; Hosseini, S. E ; Faez, R ; Sharif University of Technology
    American Institute of Physics Inc  2016
    In this paper, a silicon-on-insulator (SOI) p-n-p-n tunneling field-effect transistor (TFET) with a silicon doped hafnium oxide (Si:HfO2) ferroelectric gate stack is proposed and investigated via 2D device simulation with a calibrated nonlocal band-to-band tunneling model. Utilization of Si:HfO2 instead of conventional perovskite ferroelectrics such as lead zirconium titanate (PbZrTiO3) and strontium bismuth tantalate (SrBi2Ta2O9) provides compatibility to the CMOS process as well as improved device scalability. By using Si:HfO2 ferroelectric gate stack, the applied gate voltage is effectively amplified that causes increased electric field at the tunneling junction and reduced tunneling...