A Comprehensive Model for Gate Current in E-Mode p-GaN HEMTs
Zarak Bhat, Sheikh Aamir Ahsan
Abstract
In this article, we introduce a physics-based model aimed at elucidating the conduction mechanisms responsible for gate leakage in p-GaN/AlGaN/GaN high electron mobility transistors (HEMTs). Our model hinges on the analysis of potential variations at each interface within the p-GaN/AlGaN/GaN HEMT gate-stack. This analysis is achieved by self-consistently solving the Schrödinger-Poisson equations. To address the electrostatics at the interface, we leverage the Fermi-Dirac (FD) distribution and the 2-D-density of states. Additionally, we develop bias-dependent region-wise models, including thermionic emission (TE), thermally assisted tunneling, and Poole-Frenkel (PF) emission, to account for leakage current. To ascertain the validity of our model, we conduct a comprehensive validation against TCAD simulations and experimental data from a p-GaN HEMT, spanning a wide range of temperatures. The model through its physics-based nature has the potential to serve as a quick aid to the otherwise time-consuming TCAD simulations, in pursuit of developing enhancement mode (e-mode) GaN devices.