Significantly Enhanced Interfacial Thermal Conductance across GaN/Diamond Interfaces Utilizing AlxGa1–xN as a Phonon Bridge

Improving the thermal conductance at the GaN/diamond interface is crucial for boosting GaN-based device performance and reliability. In this study, first-principles calculations and molecular dynamics simulations were employed to explore the interfacial thermal conductance of GaN/diamond interfaces with AlxGa1–xN transition layers. The AlxGa1–xN alloy exhibits a lower thermal conductivity than GaN, primarily due to enhanced anharmonic phonon scattering. However, for the interfacial thermal conductance at the GaN/diamond interface, we discovered that introducing an AlxGa1–xN with a high Al concentration (x > 0.5) as a phonon bridge between GaN and diamond can significantly enhance the interfacial thermal conductance. In particular, it increases from 4.79 MW·m–2 K–1 to a maximum of 158 MW·m–2 K–1 at x = 0.75, surpassing the 152 MW·m–2 K–1 achieved by AlN. The AlxGa1–xN alloy has been confirmed computationally as a more efficient phonon bridge, which can provide a valuable theoretical reference for experimentally investigating the thermal management and thermal design of high-power electronic devices based on the GaN/diamond interface.