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

The β-gallium oxide (Ga 2 O 3 ) 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 (~4.8 eV) and the availability of high-quality single-crystal bulk substrates. However, the low thermal conductivity of Ga 2 O 3 (11-27 W/m-K) implies that significant thermal challenges need to be overcome to commercialize Ga 2 O 3 devices. In the present work, a single crystal (010) Ga 2 O 3 wafer was integrated with a 4H-SiC 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 Ga 2 O 3 /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.