Simulation Study of Enhancement-Mode β-Ga₂O₃ MOSFETs on a Novel P-Ga₂O₃/AlN/SiC Substrate

This work presents the design of a β-Ga₂O₃ MOSFET incorporating a P-type Ga₂O₃ buffer layer on a high-thermal-conductivity AlN/SiC composite substrate. The electrical characteristics of the device were simulated using Sentaurus TCAD. Results demonstrate that the integration of the composite substrate effectively mitigates self-heating effects, reducing the peak temperature (Tmax) from 776.5 K to 570.9 K at 300 K, while simultaneously increasing the threshold voltage (Vth) from -0.35 V to 1.52 V. Through systematic optimization of the P-Ga₂O₃ buffer layer thickness and doping concentration, the device achieves a breakdown voltage (Vbr) of 4781 V, a power figure of merit (PFOM) of 2.18 GW/cm², an IDS, on/off ratio of 9.20 × 10⁹, and cut-off/maximum oscillation frequencies (ft/fmax) of 1.29 GHz and 1.40 GHz, respectively. These findings provide a theoretical foundation for developing β-Ga₂O₃-based power devices with high breakdown voltage, improved thermal conductivity, and low specific on-resistance (Ron,sp).