Ultra-Wide Band Gap Ga₂O₃-on-SiC MOSFETs

Ultra-wide band gap semiconductor devices based on β-phase gallium oxide (Ga₂O₃) offer the potential to achieve higher switching performance and efficiency and lower manufacturing cost than that of today’s wide band gap power electronics. However, the most critical challenge to the commercialization of Ga₂O₃ electronics is overheating, which impacts the device performance and reliability. We fabricated a Ga₂O₃/4H-SiC composite wafer using a fusion-bonding method. A low-temperature (≤600 °C) epitaxy and device processing scheme was developed to fabricate MOSFETs on the composite wafer. The low-temperature-grown epitaxial Ga₂O₃ devices deliver high thermal performance (56% reduction in channel temperature) and a power figure of merit of (∼300 MW/cm²), which is the highest among heterogeneously integrated Ga₂O₃ devices reported to date. Simulations calibrated based on thermal characterization results of the Ga₂O₃-on-SiC MOSFET reveal that a Ga₂O₃/diamond composite wafer with a reduced Ga₂O₃ thickness (∼1 μm) and a thinner bonding interlayer (<10 nm) can reduce the device thermal impedance to a level lower than that of today’s GaN-on-SiC power switches.