Improving interfacial thermal conductivity by constructing covalent bond between Ga₂O₃ and SiC

Gallium oxide (Ga₂O₃) is emerging as a promising semiconductor for next-generation power and radio-frequency electronics due to its ultra-wide bandgap and high breakdown field. Yet, its intrinsic thermal conductivity is extremely low, which causes severe self-heating and limits reliable device operation. A common approach to overcome this challenge is to integrate Ga₂O₃ with substrates of high thermal conductivity such as silicon carbide (SiC). However, weak bonding across the heterojunction interface creates large thermal resistance, preventing efficient heat removal. Here we show that constructing strong covalent bonds between Ga₂O₃ and SiC through an engineered interlayer enables both structural compatibility and efficient phonon transport. This bonding strategy increases the interface thermal conductivity to 162 MW/m²·K, the highest value reported for Ga₂O₃ heterostructures. Infrared thermography confirms that the bonded devices exhibit a temperature reduction of up to 29 °C under high power densities, demonstrating significant mitigation of self-heating. These findings establish a practical route for enhancing thermal management in Ga₂O₃ electronics and highlight the importance of interfacial bonding design. Beyond Ga₂O₃, this approach may be extended to other wide-bandgap semiconductors where thermal bottlenecks constrain device performance.