RESURF Ga₂O₃-on-SiC Field Effect Transistors for Enhanced Breakdown Voltage

Heterosubstrates have been extensively studied as a method to improve the heat dissipation of Ga2O3 devices. In this simulation work, we propose a novel role for p-type available heterosubstrates, as a component of a reduced surface field (RESURF) structure in Ga2O3 lateral field-effect transistors (FETs). The RESURF structure can eliminate the electric field crowding and contribute to higher breakdown voltage. Using SiC as an example, the designing strategy for doping concentration and dimensions of the p-type region is systematically studied using TCAD modeling. Meanwhile, the interface charges and Al2O3 interlayer that could exist in realistic devices are mimicked in the simulation. Additionally, the feasibility of the RESURF structure for high-frequency switching operation is supported by the simulation on charging/discharging time the p-SiC depletion region. This study demonstrates the great potential of utilizing the electrical properties of heat-dissipating heterosubstrates to achieve a uniform electric field distribution in Ga2O3 FETs.