The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Gilles Horowitz - One of the best experts on this subject based on the ideXlab platform.

  • extracting parameters from the current Voltage characteristics of organic field effect transistors
    Advanced Functional Materials, 2004
    Co-Authors: Gilles Horowitz, Philippe Lang, Mohamad Mottaghi, Herve Aubin
    Abstract:

    Organic field-effect transistors were fabricated with vapor-deposited pentacene on aluminum oxide insulating layers. Several methods are used in order to extract the mobility and threshold Voltage from the transfer characteristic of the devices. In all cases, the mobility is found to depend on the Gate Voltage. The first method consists of deriving the drain current as a function of Gate Voltage (transconductance), leading to the so-called field-effect mobility. In the second method, we assume a power-law dependence of the mobility with Gate Voltage together with a constant contact resistance. The third method is the so-called transfer line method, in which several devices with various channel length are used. It is shown that the mobility is significantly enhanced by modifying the aluminum oxide layer with carboxylic acid self-assembled monolayers prior to pentacene deposition. The methods used to extract parameters yield threshold Voltages with an absolute value of less than 2 V. It is also shown that there is a shift of the threshold Voltage after modification of the aluminum oxide layer. These features seem to confirm the validity of the parameter-extraction methods.

  • temperature and Gate Voltage dependence of hole mobility in polycrystalline oligothiophene thin film transistors
    Journal of Applied Physics, 2000
    Co-Authors: Gilles Horowitz, Mohsen Elain Hajlaoui, Riadh Hajlaoui
    Abstract:

    We have performed current–Voltage measurement on polycrystalline sexithiophene (6 T) thin film transistors at temperatures ranging from 10 to 300 K. A method is developed to extract the carrier mobility from an analysis of the transfer characteristics. In particular, data are corrected for contact resistance. The carrier mobility is found to increase quasilinearly with Gate Voltage at room temperature. The dependence becomes superlinear at low temperatures. The temperature dependence shows three domains. For 100 K

  • Gate Voltage dependent mobility of oligothiophene field effect transistors
    Journal of Applied Physics, 1999
    Co-Authors: Gilles Horowitz, Riadh Hajlaoui, Denis Fichou, Ahmed El Kassmi
    Abstract:

    Organic field-effect transistors, in which the active semiconductor is made of oligothiophenes of various lengths, have been fabricated and characterized. A method is developed to estimate the field-effect mobility μ corrected for the contact series resistance. The mobility is found to increase by a factor of nearly 100 from quaterthiophene (4T) to octithiophene (8T). More importantly, μ increases quasilinearly with Gate Voltage. The origin of this Gate bias dependence is discussed. One explanation could be the presence of traps that limit charge transport. Alternatively, the Gate-Voltage dependence is tentatively attributed to a dependence of the mobility with the concentration of carriers in the accumulation layer.

Derrick Holliday - One of the best experts on this subject based on the ideXlab platform.

  • high speed resonant Gate driver with controlled peak Gate Voltage for silicon carbide mosfets
    IEEE Transactions on Industry Applications, 2014
    Co-Authors: Philip Anthony, Neville Mcneill, Derrick Holliday
    Abstract:

    Parasitic inductance in the Gate path of a silicon carbide MOSFET places an upper limit upon the switching speeds achievable from these devices, resulting in unnecessarily high switching losses due to the introduction of damping resistance into the Gate path. A method to reduce switching losses is proposed, using a resonant Gate driver to absorb parasitic inductance in the Gate path, enabling the Gate resistor to be removed. The Gate Voltage is maintained at the desired level using a feedback loop. Experimental results for a 1200-V silicon carbide MOSFET Gate driver are presented, demonstrating the switching loss of 230 μJ at 800 V and 10 A. This represents a 20% reduction in switching losses in comparison to that of conventional Gate drive methods.

  • High-Speed Resonant Gate Driver With Controlled Peak Gate Voltage for Silicon Carbide MOSFETs
    IEEE Transactions on Industry Applications, 2014
    Co-Authors: Philip Anthony, Neville Mcneill, Derrick Holliday
    Abstract:

    Parasitic inductance in the Gate path of a silicon carbide MOSFET places an upper limit upon the switching speeds achievable from these devices, resulting in unnecessarily high switching losses due to the introduction of damping resistance into the Gate path. A method to reduce switching losses is proposed, using a resonant Gate driver to absorb parasitic inductance in the Gate path, enabling the Gate resistor to be removed. The Gate Voltage is maintained at the desired level using a feedback loop. Experimental results for a 1200-V silicon carbide MOSFET Gate driver are presented, demonstrating the switching loss of 230 μJ at 800 V and 10 A. This represents a 20% reduction in switching losses in comparison to that of conventional Gate drive methods

  • high speed resonant Gate driver with controlled peak Gate Voltage for silicon carbide mosfets
    European Conference on Cognitive Ergonomics, 2012
    Co-Authors: Philip Anthony, Neville Mcneill, Derrick Holliday
    Abstract:

    Parasitic inductance in the Gate path of a Silicon Carbide MOSFET places an upper limit upon the switching speeds achievable from these devices, resulting in unnecessarily high switching losses due to the introduction of damping resistance into the Gate path. A method to reduce switching losses is proposed, using a resonant Gate driver to absorb parasitic inductance in the Gate path, enabling the Gate resistor to be removed. The Gate Voltage is maintained at the desired level using a feedback loop. Experimental results for a 1200 V Silicon Carbide MOSFET Gate driver are presented, demonstrating switching loss of 230 µJ at 800 V, 10 A. This represents a 20% reduction in switching losses in comparison to conventional Gate drive methods.

  • High-speed resonant Gate driver with controlled peak Gate Voltage for silicon carbide MOSFETs
    2012 IEEE Energy Conversion Congress and Exposition (ECCE), 2012
    Co-Authors: Philip Anthony, Neville Mcneill, Derrick Holliday
    Abstract:

    Parasitic inductance in the Gate path of a Silicon Carbide MOSFET places an upper limit upon the switching speeds achievable from these devices, resulting in unnecessarily high switching losses due to the introduction of damping resistance into the Gate path. A method to reduce switching losses is proposed, using a resonant Gate driver to absorb parasitic inductance in the Gate path, enabling the Gate resistor to be removed. The Gate Voltage is maintained at the desired level using a feedback loop. Experimental results for a 1200 V Silicon Carbide MOSFET Gate driver are presented, demonstrating switching loss of 230 μJ at 800 V, 10 A. This represents a 20% reduction in switching losses in comparison to conventional Gate drive methods

Michael S Fuhrer - One of the best experts on this subject based on the ideXlab platform.

  • insulating behavior in ultra thin bismuth selenide field effect transistors
    arXiv: Mesoscale and Nanoscale Physics, 2012
    Co-Authors: Sungjae Cho, Nicholas P Butch, Johnpierre Paglione, Michael S Fuhrer
    Abstract:

    Ultrathin (~3 quintuple layer) field-effect transistors (FETs) of topological insulator Bi2Se3 are prepared by mechanical exfoliation on 300nm SiO2/Si susbtrates. Temperature- and Gate-Voltage dependent conductance measurements show that ultrathin Bi2Se3 FETs are n-type, and have a clear OFF state at negative Gate Voltage, with activated temperature-dependent conductance and energy barriers up to 250 meV.

  • insulating behavior in ultrathin bismuth selenide field effect transistors
    Nano Letters, 2011
    Co-Authors: Sungjae Cho, Nicholas P Butch, Johnpierre Paglione, Michael S Fuhrer
    Abstract:

    Ultrathin (approximately three quintuple layer) field-effect transistors (FETs) of topological insulator Bi2Se3 are prepared by mechanical exfoliation on 300 nm SiO2/Si susbtrates. Temperature- and Gate-Voltage-dependent conductance measurements show that ultrathin Bi2Se3 FETs are n-type and have a clear OFF state at negative Gate Voltage, with activated temperature-dependent conductance and energy barriers up to 250 meV.

  • Gate tunable graphene spin valve
    Applied Physics Letters, 2007
    Co-Authors: Yung Fu Chen, Michael S Fuhrer
    Abstract:

    The authors perform nonlocal four-probe spin-valve experiments on graphene contacted by ferromagnetic Permalloy electrodes. They observe sharp switching and often sign reversal of the nonlocal resistance at the coercive field of the electrodes, indicating the presence of a spin current between injector and detector. The nonlocal spin-valve signal changes magnitude and sign with back-Gate Voltage, and is observed up to T=300K. The Gate Voltage variation of the spin-valve signal may result from quantum-coherent transport, as evidenced by Fabry-Perot-like oscillations of the current.

Riadh Hajlaoui - One of the best experts on this subject based on the ideXlab platform.

  • temperature and Gate Voltage dependence of hole mobility in polycrystalline oligothiophene thin film transistors
    Journal of Applied Physics, 2000
    Co-Authors: Gilles Horowitz, Mohsen Elain Hajlaoui, Riadh Hajlaoui
    Abstract:

    We have performed current–Voltage measurement on polycrystalline sexithiophene (6 T) thin film transistors at temperatures ranging from 10 to 300 K. A method is developed to extract the carrier mobility from an analysis of the transfer characteristics. In particular, data are corrected for contact resistance. The carrier mobility is found to increase quasilinearly with Gate Voltage at room temperature. The dependence becomes superlinear at low temperatures. The temperature dependence shows three domains. For 100 K

  • Gate Voltage dependent mobility of oligothiophene field effect transistors
    Journal of Applied Physics, 1999
    Co-Authors: Gilles Horowitz, Riadh Hajlaoui, Denis Fichou, Ahmed El Kassmi
    Abstract:

    Organic field-effect transistors, in which the active semiconductor is made of oligothiophenes of various lengths, have been fabricated and characterized. A method is developed to estimate the field-effect mobility μ corrected for the contact series resistance. The mobility is found to increase by a factor of nearly 100 from quaterthiophene (4T) to octithiophene (8T). More importantly, μ increases quasilinearly with Gate Voltage. The origin of this Gate bias dependence is discussed. One explanation could be the presence of traps that limit charge transport. Alternatively, the Gate-Voltage dependence is tentatively attributed to a dependence of the mobility with the concentration of carriers in the accumulation layer.

Daniel C Frisbie - One of the best experts on this subject based on the ideXlab platform.

  • Gated four probe measurements on pentacene thin film transistors contact resistance as a function of Gate Voltage and temperature
    Journal of Applied Physics, 2004
    Co-Authors: Paul V Pesavento, Reid J Chesterfield, Christopher R Newman, Daniel C Frisbie
    Abstract:

    We describe Gated four-probe measurements designed to measure contact resistance in pentacene-based organic thin-film transistors (OTFTs). The devices consisted of metal source and drain electrodes contacting a 300-A-thick pentacene film thermally deposited on Al2O3 or SiO2 dielectrics with a p-doped Si substrate serving as the Gate electrode. Voltage-sensing leads extending into the source-drain channel were used to monitor potentials in the pentacene film while passing current during drain Voltage (VD) or Gate Voltage (VG) sweeps. We investiGated the potential profiles as a function of contact metallurgy (Pt, Au, Ag, and Ca), substrate chemistry, VG, and temperature. The contact-corrected linear hole mobilities were as high as 1.75cm2∕Vs and the film sheet resistance and specific contact resistance were as low as 600kΩ∕◻ and 1.3kΩ-cm, respectively, at high Gate Voltages. In the temperature range of 50–200K, the pentacene OTFTs displayed an activated behavior with activation energies of 15–30meV. Importa...

  • organic thin film transistors based on n alkyl perylene diimides charge transport kinetics as a function of Gate Voltage and temperature
    Journal of Physical Chemistry B, 2004
    Co-Authors: Reid J Chesterfield, Christopher R Newman, John C Mckeen, Paul C Ewbank, Demetrio A Da Silva Filho, Jeanluc Bredas, Larry L Miller, And Kent R Mann, Daniel C Frisbie
    Abstract:

    We report structural and electrical transport properties of a family of π-stacking soluble organic semiconductors, N,N‘-dialkyl-3,4,9,10-perylene tetracarboxylic diimides (alkyl − pentyl [1], octyl [2], and dodecyl [3]). The structures of evaporated polycrystalline films of 1−3 were studied using X-ray diffraction and atomic force microscopy. Films of 1−3 pack similarly with the direction of π−π overlap in the substrate plane. Organic thin film transistors (OTFTs) based on 1−3 deposited on SiO2 Gate dielectric showed linear regime electron mobilities of 0.1, 0.6, and 0.2 cm2/(V s), respectively, corrected for contact resistance. OTFTs of 2 had saturation electron mobilities as high as 1.7 cm2/(V s) with on-to-off current ratios of 107. Variable temperature measurements were used to examine the charge transport kinetics in the range 80−300 K and revealed (1) thermally activated electron mobilities with activation energies dependent on Gate Voltage and (2) the presence of well-defined isokinetic points, i.e...