Theoretical study of carrier transport with quantum confinement effects in GaN HEMT by the Schrödinger-equation modulated drift–diffusion model

Abstract

In GaN high electron mobility transistors, the polarization effects induce a strong electric field, which approximately creates a triangular potential well at the AlGaN/GaN interface, leading to strong quantum confinement and the formation of a two-dimensional electron gas. High electron density and mobility in 2DEG contribute to the outstanding performance of GaN HEMT. However, most studies on quantum confinement effects in 2DEG relied on the density gradient model or considered only one-dimensional carrier transport. In this paper, we propose a Schrödinger-equation modulated drift–diffusion model to account for both the quantum confinement in vertical direction and drift–diffusion transport in cross-sectional region of a typical depletion-mode GaN HEMT. The proposed model can capture the electron distribution in 2DEG more accurately, thereby aiding in more precise analyses of device performance and reliability under non-ideal conditions, such as interface roughness scattering and heterojunction interface recombination. Additionally, the proposed model reveals noticeable differences in gate capacitance in the subthreshold region when compared to classical models.