Analytical Models for the electric field and potential of AlGaN/GaN HEMT with partial silicon doping

Abstract

Here, we study the mechanism of AlGaN/GaN HEMT with the partial silicon doping in the AlGaN layer under reverse bias and propose a two-dimensional analytic model for this device. The local density of two-dimensional electron gas (2DEG) increase at the interface between the AlGaN and GaN buffer due to partial silicon positive charge. And a new electric field peak is introduced by electric field modulation effect, which makes the electric field distribution of the channel surface more uniform and increases the breakdown voltage of the device. An analytical expression for the electric field and potential distribution of the channel is obtained, based on the two-dimensional Poisson's equation with appropriate boundary conditions. With this model, we explain the effects of silicon doping concentration and doping length on channel potential and electric field distribution in detail. By comparing the results obtained by the analytical model with the simulation results of Silvaco TCAD software, the numerical results and simulation results mostly match which verifies the validity of the model and provides a reference to model other AlGaN/GaN HEMTs.