Modeling the Impact of Dynamic Fin-Width on the I– V, C– V and RF Characteristics of GaN Fin–HEMTs

Abstract

In this article, we introduce an engineering approach to model the current and charge characteristics of an AlGaN/GaN Fin–HEMT. The model handles the effective width of the 2DEG channel by considering its depletion due to the presence of gates on the sidewalls of the fin. This width modulation of the 2DEG, and the bias-dependence associated with it, significantly affects the transconductance and the capacitance behavior of the device. In this work, we modify and couple two industry-standard compact models: 1) the advanced SPICE model for GaN HEMTs (ASM-GaN-HEMT) model and 2) the Berkeley short-channel insulated-gate FET model for common multiple gate (BSIM-CMG) model. While the former provides the physics-based calculations for electrostatics and transport in the 2DEG, the latter is incorporated to account for the width-modulation due to the sidewalls. The developed methodology is validated for dc, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${C}$ </tex-math></inline-formula> – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}$ </tex-math></inline-formula> , and RF behavior against experimental data of GaN Fin–HEMTs. To the authors’ knowledge, this is the first compact model that provides an end-to-end dc–radio frequencies (RF) modeling solution for the state-of-the-art GaN Fin–HEMTs and therefore could play a role in the evolution of the GaN Fin–HEMT technology.