Effective Suppression of MIS Interface Defects Using Boron Nitride toward High-Performance Ta-Doped-β-Ga2O3 MISFETs

β-Ga2O3 is considered an attractive candidate for next-generation high-power electronics due to its large band gap of 4.9 eV and high breakdown electrical field of 8 MV/cm. However, the relatively low carrier concentration and low electron mobility in the β-Ga2O3-based device limit its application. Herein, the high-quality β-Ga2O3 single crystal with high doping concentration of ∼3.2 × 1019 cm-3 was realized using an optical float-zone method through Ta doping. In contrast to the SiO2/β-Ga2O3 gate stack structure, we used hexagonal boron nitride as the gate insulator, which is sufficient to suppress the metal-insulator-semiconductor (MIS) interface defects of the β-Ga2O3-based MIS field-effect transistors (FETs), exhibiting outstanding performances with a low specific on-resistance of ∼6.3 mΩ·cm2, a high current on/off ratio of ∼108, and a high mobility of ∼91.0 cm2/(V s). Our findings offer a unique perspective to fabricate high-performance β-Ga2O3 FETs for next-generation high-power nanoelectronic applications.