3-D Modeling for Electrical Optimization of Delta-Doped β-Ga₂O₃ MOSFETs with Anisotropic Electrothermal Properties

The high critical electric field strength and ultra wide bandgap of β -Ga2O3 make it promising for power electronics, but the low thermal conductivity necessitates extensive focus on thermal management. This study focuses on enhancing the electrical performance of β -Ga2O3 metal-oxide-semiconductor field-effect transistors (MOSFETs) with optimized heat dissipation using a 3-D electrothermal model. We take into account the anisotropic mobility and thermal conductivity, channel orientation, and delta-doping process for electrical optimization. Our results indicate that thermal conductivity anisotropy significantly impacts the electrical characteristics more than mobility anisotropy does. Simulations of MOSFETs with various channel orientations reveal that β -Ga2O3 with a 45° (010)-oriented channel exhibits superior electrical performance due to the highest thermal conductivity. The investigation of delta-doping effects shows that higher charge density increases the breakdown voltage by broadening the depletion region, with an optimal value of 5× 1013cm-2. Excessive doping density, however, risks local breakdown. Positioning the delta-doping layer near the channel interface homogenizes the electric field and enhances the breakdown voltage, but excessive proximity can be harmful. Our optimized β -Ga2O3 MOSFET design achieves a high off-state breakdown voltage (Vbr =2284 V) and a high-power figure of merit (PFOM = 369.5 MV/cm2) at a low specific on-resistance (Ron, sp =14.1 mΩ cm2). This work highlights the necessity for synergistic design practices in β -Ga2O3 MOSFETs, which integrates both electrical and thermal considerations.