A strategy for enhancing interfacial thermal transport in Ga2O3-diamond composite structure by introducing an AlN interlayer

Heat dissipation issues have emerged in power devices due to miniaturization and high power density, particularly for materials like low-thermal-conductivity gallium oxide (Ga₂O₃). Increasing interfacial heat transfer has been identified as a critical strategy for tackling these issues. This study first explored the thermal transport of Ga₂O₃-diamond interfaces in composite structures containing an AlN interlayer. First-principles calculations revealed that the AlN interlayer improved interfacial bonding between Ga₂O₃ and diamond. Subsequently, Ga₂O₃ membranes were deposited on diamond substrates with and without interlayers using pulsed laser deposition (PLD), and the structural and thermal characteristics were examined. The interlayer strategy was shown to be effective in improving the quality of Ga₂O₃ thin films, including improved crystallinity, a smoother surface, and fewer oxygen vacancies. The thermal characteristics were accordingly improved: the thermal conductivity of Ga₂O₃ increased from 5.5±0.3–6.0±0.3 W/m·K, and the thermal boundary conductance of Ga₂O₃-diamond interface (TBC_GaO-dia) increased from 46.1±2.3–60.9±3.0 MW/m²·K. Molecular dynamics (MD) analysis further revealed that the enhancement in phonon transmission was due to the increase in the low-frequency phonon participation rate. Additionally, the electro-thermal simulation using COMSOL confirmed the effectiveness of the AlN interlayer in mitigating the self-heating effect. These findings offer a new route for improving interface heat transport and pave the way for the optimization and design of reliable Ga₂O₃-based devices.