Now showing 1 - 6 of 6
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    Evidence of Fowler-Nordheim tunneling in gate leakage current of AlGaN/GaN HEMTs at room temperature
    (01-12-2014)
    Turuvekere, Sreenidhi
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    Rawal, Dipendra Singh
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    Dependence of gate leakage current on Al mole fraction of AlGaN/GaN high-electron mobility transistors (HEMTs) is studied using temperature-dependent current-voltage and capacitance-voltage characteristics. The reverse leakage current is mostly dominated by Poole-Frenkel (PF) emission in the structures used in this brief. However, it is observed that at higher mole fractions, due to higher electric field across the barrier, Fowler-Nordheim (FN) tunneling also contributes to the gate leakage current even at room temperature and above. An expression for critical temperature below which FN tunneling component becomes comparable with or more than PF emission component is presented. It is concluded that the dominant gate leakage mechanisms in III - N HEMTs are dependent on mole fraction of the barrier material and the temperature. However, the relative strengths of PF emission and FN tunneling are also influenced by various process-dependent parameters.
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    An analytical charge control model for AlGaN/GaN HEMT including the gate bias dependence on polarization charge
    (01-01-2012)
    Karumuri, Naveen
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    Sreenidhi, T.
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    A closed form analytical expression for the 2DEG (channel charge) in AlGaN/GaN HEMT is presented. This includes the effect of transverse electric field on the piezoelectric bound charge due to electromechanical coupling. The present model explains the dependence of bound piezoelectric charge and channel 2DEG concentration on gate bias. Models with and without electromechanical coupling are compared and explained. © 2012 IEEE.
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    A Compact Model of Drain Current for GaN HEMTs Based on 2-DEG Charge Linearization
    (01-11-2016)
    Karumuri, Naveen
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    Dutta, Gourab
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    A physics-based simple and accurate compact model of drain current for GaN-based high electron mobility transistors (HEMTs) is presented. The model is developed using analytical relations for charges in the 2-D electron gas and barrier layer. For the first time, a simple charge linearization approach has been used for GaN-based HEMTs. The access regions are accurately modeled using transistors. The model is rigorously validated over a wide range of geometries and parameters for AlGaN/GaN and AlInN/GaN HEMTs. The model also passes the DC Gummel symmetry test.
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    Effect of barrier layer thickness on gate leakage current in AlGaN/GaN HEMTs
    (01-10-2015)
    Turuvekere, Sreenidhi
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    Gate leakage current mechanisms in Al0.28Ga0.72N/GaN high-electron mobility transistors with different barrier thicknesses are studied using temperature-dependent current-voltage characteristics. Poole-Frenkel emission and Fowler-Nordheim tunneling are observed in the reverse bias. Beyond the threshold voltage, increase in gate leakage current with the increase in barrier thickness is observed. Furthermore, the gate leakage current has negative temperature dependence over a wide range of temperatures especially for the devices with a thicker barrier. This has been qualitatively explained with the help of secondary electron-hole pair generation in the channel.
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    Publication
    Effect of Sputtered-Al2O3 Layer Thickness on the Threshold Voltage of III-Nitride MIS-HEMTs
    (01-04-2016)
    Dutta, Gourab
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    Dependence of threshold voltage (VTh) on oxide thickness (tox) for GaN-based metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs) using sputter-deposited Al2O3 as gate dielectric is studied in detail. Different III-nitride (III-N) heterostructures (AlGaN/GaN and AlInN/GaN) with/without GaN cap layer were used for fabricating these MIS devices. Interestingly, for all the sets of devices, a positive shift in VTh was observed initially with a increase in tox, followed by a negative shift of the same. A comprehensive analytical model has been proposed to explain the variation of VTh with tox and has been shown to match the experimental data for MIS-HEMTs fabricated on different heterostructures and with different values of tox. This model allows the extraction of different charge components in the oxide or at oxide/III-N interface. Normally OFF AlInN/GaN MIS-HEMTs with VTh of +0.67 V have been demonstrated with the optimized tox of sputtered Al2O3.
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    Gate Leakage Mechanisms in AlInN/GaN and AlGaN/GaN MIS-HEMTs and Its Modeling
    (01-09-2017)
    Dutta, Gourab
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    Gate leakage mechanisms in AlInN/GaN and AlGaN/GaN metal insulator semiconductor high-electron-mobility transistors (MIS-HEMTs) with SiNx as gate dielectric have been investigated. It is found that the conduction in the reverse gate bias is due to Poole-Frenkel emission for both MIS-HEMTs. The dominant conduction mechanism in low to medium forward bias is trap-assisted tunneling while it is Fowler-Nordheim tunneling at high forward bias. However, conduction near zero gate bias is dominated by defect-assisted tunneling for both sets of MIS-HEMTs. The gate leakage current is primarily dependent on the properties of the gate dielectric material and dielectric/semiconductor interface rather than the barrier layer. A model is proposed for the gate leakage current in GaN-based MIS-HEMTs, and the method to extract the related model parameters is also presented in this paper. The proposed gate current model matches well with the experimental results for both AlInN/GaN and AlGaN/GaN MIS-HEMTs over a wide range of gate bias and measurement temperature.