3-D Modeling for Electrical Optimization of Delta-Doped β -Ga 2 O 3 MOSFETs With Anisotropic Electrothermal Properties

The high critical electric field strength and ultra wide bandgap of $\beta $ -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 $\beta $ -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 $\beta $ -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 $5\times 10^{{13}}$ cm ${}^{-2}$ . 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 $\beta $ -Ga₂O₃ MOSFET design achieves a high off-state breakdown voltage ( $V$ ${}_{\text {br}} =2284$ V) and a high-power figure of merit (PFOM = 369.5 MV/cm²) at a low specific on-resistance ( $R$ ${}_{\textsc{on}, \text{sp}} =14.1$ m $\Omega ~\cdot $ cm²). This work highlights the necessity for synergistic design practices in $\beta $ -Ga₂O₃ MOSFETs, which integrates both electrical and thermal considerations.