Ultra-Wide Band Gap Ga2O3-on-SiC MOSFETs

Ultra-wide band gap semiconductor devices based on fi-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 degrees 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 (similar to 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 (similar to 1 mu m) 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.

Automated summary

Ultra-wide band gap semiconductor devices based on fi-phase gallium oxide (Ga2O3) offer higher switching performance, efficiency, and lower manufacturing cost compared to current wide band gap power electronics. However, overheating remains the major challenge for the commercialization of Ga2O3 electronics, affecting device performance and reliability. By fabricating a Ga2O3/4H-SiC composite wafer and implementing a low-temperature epitaxy and device processing scheme, we achieved high thermal performance and a power figure of merit of 300 MW/cm2 in Ga2O3 devices, the highest reported thus far. Thermally optimized Ga2O3/diamond composite wafers with reduced Ga2O3 thickness and thinner bonding interlayers show potential for further reduction in device thermal impedance.