Breakdown voltage improvement and analysis of GaN HEMTs through field plate inclusion and substrate removal

Abstract

Extensive studies have concluded that breakdown mechanisms in Gallium Nitride (GaN) High Electron Mobility Transistors (HEMT) can be improved by substrate reduction and the addition of field plate (FP) on their structures. A theoretical analysis of the FP effects on the HEMT is carried out by modeling the electric fields inside the structure. The electric field model is deduced by solving the potential in the heterostructure, which should satisfy the Poisson equation. A comprehensive physics-based model of a common HEMT provides the base comparison to conduct two analyses: 1) a reduction of the silicon substrate and 2) the addition of different FPs. The electric field distribution across the source, gate, and drain is analyzed for each geometric case in order determine the breakdown voltage origin as well as their I-V characteristic curves.