MODELLING 2DEG CHARGES IN AlGaN/GaN HETEROSTRUCTURES

In this paper we compare different approaches to calculating the charge density in the 2DEG layer of AlGaN/GaN HEMTs. The methods used are (i) analytical theory implemented in MATLAB, (ii) finite-element analysis using semiconductor TCAD software that implements only the Poisson and continuity equations, and (iii) 1D software that solves the Poisson and Schrodinger equations self-consistently. By using the 1D Poisson-Schrodinger solver, we highlight the consequences of neglecting the Schrodinger equation. We conclude that the TCAD simulator predicts with a reasonable level of accuracy the electron density in the 2DEG layer for both a conventional HEMT structure and one featuring an extra GaN cap layer. In addition, while the sheet charge density is not significantly affected by including Schrodinger, its confinement in the channel is found to be modified.