Abstract
In this article, the gate current in AlGaN/GaN high-electron mobility transistors is modeled in a surface potential-based compact model. The thermionic emission, the Poole–Frenkel emission, and the Fowler–Nordheim tunneling are the dominant mechanisms for the gate current in the forward- and reverse-bias regions. These conduction mechanisms are modeled within the framework of the ASM-GaN compact model, which is a physics-based industry-standard model for GaN HEMTs, hence yielding a consistent model for the drain and gate currents. The proposed model captures the gate voltage, drain voltage, temperature, and gate-length dependencies of the gate current. The results of dc gate-leakage measurements of two GaN HEMT, differing only in terms of gate length, over a wide range of temperature, showing these current-conduction mechanisms, are presented, and the proposed model is validated accordingly. The developed gate current model, implemented in Verilog-A, is in excellent agreement with the experimental data.
Highlights
T HE GaN-based high-electron mobility transistors (HEMTs) have been proven to possess significantly superior characteristics in comparison to other III/V material systems
In the ASM GaN compact model, this mathematical relationship is developed from device physics, starting with the fundamental device physics governed by Schrfördinger’s and Poisson’s equations in the quantum well of the GaN HEMT [9]
Our analysis of the measured characteristics of the devices under test shows, in agreement with the results reported in the literature [17], [19], that accurate modeling of these characteristics requires inclusion of temperature dependence for the Schottky barrier height φTE and the ideality-factor parameter η as nature and the carrier-capture radius of each individual dislocation depend on factors such as types and distribution of dislocations and III/V ratios during epitaxial growth [1], it is difficult to incorporate the impact of threading dislocations into a gate leakage model
Summary
T HE GaN-based high-electron mobility transistors (HEMTs) have been proven to possess significantly superior characteristics in comparison to other III/V material systems. The performance of both digital and analog circuits can get affected by the noise associated with the gate current [5], [8] These concerns showcase the importance of accurate modeling of the gate leakage, which mostly has either been ignored in compact models for GaN HEMTs or been implemented empirically. In the ASM GaN compact model, this mathematical relationship is developed from device physics, starting with the fundamental device physics governed by Schrfördinger’s and Poisson’s equations in the quantum well of the GaN HEMT [9] In this model, the terminal device characteristics are functions of the surface potential ψ, which, in turn, is a function of the input bias, device geometry, and temperature.
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