Ultra-Wide Band Gap GaO-on-SiC MOSFETs.

Ultra-wide band gap semiconductor devices based on β-phase gallium oxide (GaO) 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 GaO electronics is overheating, which impacts the device performance and reliability. We fabricated a GaO/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 GaO devices deliver high thermal performance (56% reduction in channel temperature) and a power figure of merit of (∼300 MW/cm), which is the highest among heterogeneously integrated GaO devices reported to date. Simulations calibrated based on thermal characterization results of the GaO-on-SiC MOSFET reveal that a GaO/diamond composite wafer with a reduced GaO 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.