Selective Direct Bonding of High Thermal Conductivity 3C-SiC Film to \b{eta}-Ga2O3 for Top-Side Heat Extraction

beta-Ga2O3 is a wide bandgap semiconductor with electrical properties better than SiC and GaN which makes it promising for applications of next-generation power devices. However, the thermal conductivity of \b{eta}-Ga2O3 is more than one order of magnitude lower than that of SiC and GaN, resulting in serious thermal management problems that limit device performance and reliability. This work reports selectively transferring of high thermal conductivity 3C-SiC thin film grown on Si to beta-Ga2O3 (001) substrate using surface activated bonding (SAB) technique at room temperature, to attempt extracting the heat from the surface of the devices. A 4.5-nm-thick interfacial crystal defect layer is formed at the as-bonded 3C-SiC/beta-Ga2O3 interface. The thickness of the interfacial crystal defect layer decreases with increasing annealing temperature, which decreases to 1.5 nm after annealing at 1000 C. No voids and unbonded area are observed at the interfaces, even after annealing at temperature as high as 1000 C. The thermal boundary conductance (TBC) of the 1000 C-annealed 3C-SiC/beta-Ga2O3 interface and thermal conductivity of the beta-Ga2O3 substrate was measured by time-domain thermoreflectance (TDTR). The 3C-SiC/beta-Ga2O3 TBC value was determined to be 244 MW/m2-K, which is the highest value ever reported for SiC/Ga2O3 interfaces, due to the high-quality heterointerface. Our works demonstrate that selective transferring of 3C-SiC film to the beta-Ga2O3 substrate is an efficient path to improve heat dissipation of the \b{eta}-Ga2O3 power devices.