3 kV-Class β -Ga 2 O 3 Lateral MOSFETs With Superior High-Temperature Leakage Suppression Enabled by an Ozone-Grown Semi-Insulating Buffer Layer

Ultra wide bandgap$\beta $-Ga2O3holds great promise for next-generation high-voltage power electronics, yet its practical application is severely hampered by premature breakdown and excessiveoff-state leakage at elevated temperatures. Here, we address the critical challenge by introducing an O3-assisted-grown semi-insulating buffer layer in lateral$\beta $-Ga2O3MOSFETs. The buffer layer exhibits a high density of deep-level acceptor defects, specifically gallium vacancies and gallium-oxygen divacancy complexes, as revealed by photoluminescence spectroscopy, which effectively compensate thermally activated carriers and suppress leakage pathways. Devices incorporating this buffer layer achieve a record breakdown voltage exceeding 3 kV among pulsed laser deposition (PLD)-grown lateral$\beta $-Ga2O3MOSFETs without a field plate, and a specificon-resistance of 206.84 m$\Omega \cdot $cm2. Moreover, at an operating temperature of$200~^{\circ }$C, theoff-state leakage current is reduced by nearly two orders of magnitude compared to devices without the buffer layer. Temperature-dependent current–voltage measurements and TCAD simulations reveal that the superior high-temperature insulation originates from the deep level defects (2.4–3.1 eV) in the O3-grown buffer layer, which contrasts with the shallower Fe-related acceptor level (~0.8 eV) in conventional substrates. This work demonstrates that defect-engineered buffer layers offer a viable and scalable pathway to achieve exceptional high-temperature stability in$\beta $-Ga2O3lateral power devices.