Thermal Transport Properties of β-Ga₂O₃ Thin Films on Si and SiC Substrates Fabricated by an Ion-Cutting Process

Abstract

Integrating β-Ga 2 O 3 films onto a highly thermally conductive substrate is regarded as a promising method to remove the heat from β-Ga 2 O 3 high-power devices, ultimately increasing their reliability and performance. In this work, we fabricated three wafer-scale heterogeneous integration materials (HIMs), i.e., β-, by using ion-cutting and surfaceactivated bonding techniques. The heat block effect of the intermediate amorphous Al 2 O 3 layer from β-Ga 2 O 3 to SiC is significantly relieved by employing a post-annealing process. Furthermore, the Al 2 O 3 layer blocks the interfusion of elements between β-Ga 2 O 3 and the host substrate, avoiding the degradation of thermal conductivity of β-Ga 2 O 3 films after post-annealing. Benefited from this, a relatively high thermal conductivity (9.3 W/m•K) is achieved among β-Ga 2 O 3 thin films with the same thickness and the effective thermal boundary conductance was improved in all β-Ga 2 O 3 HIMs. One to two orders of magnitude reduction in the junction-to-package device thermal resistance is revealed by the thermal modeling of β-Ga 2 O 3 HIM metal-oxidesemiconductor field-effect transistors, which demonstrates that extremely high heat dissipation can be realized by optimizing the TBR eff value and integrating with thermally conductive substrates (SiC and diamond). These results give key guidelines to engineer the thermal transport properties of β-Ga 2 O 3 HIMs for device thermal management.