Characterization of the Thermal Boundary Resistance of a Ga₂O₃/4H-SiC Composite Wafer

The beta-gallium oxide (Ga2O3) material system offers the potential to dramatically improve the electrical performance and cost-effectiveness of next-generation power electronics. This is because of its ultra-wide bandgap (similar to 4.8 eV) and the availability of high-quality single-crystal bulk substrates. However, the low thermal conductivity of Ga2O3 (11- 27 W/mK) implies that significant thermal challenges need to be overcome to commercialize Ga2O3 devices. In the present work, a single crystal (010) Ga2O3 wafer was integrated with a 4HSiC substrate via fusion bonding to address this concern of poor thermal conductivity. A differential steady-state thermoreflectance method was established to measure the thermal boundary resistance at the Ga2O3/SiC interface (100 m(2)K/GW), which has yet to be reported due to the limited probing depth of conventional frequency- and time-domain thermoreflectance techniques.