Influence of temperature on the bonding behavior of GaN on diamond with Ta-Au interlayer: Insights from molecular dynamics simulations

This study employs molecular dynamics (MD) simulations to investigate the interfacial bonding behavior between GaN and diamond substrates using a Ta-Au-Ta metallic interlayer. Given the limitations of conventional substrates in thermal management of high-power GaN devices, diamond is considered a promising alternative due to its exceptional thermal conductivity. However, the direct integration of GaN and diamond faces significant challenges stemming from lattice mismatch and differences in thermal expansion coefficients. To address this issue, a GaN/Ta–Au–Ta/diamond structural model was constructed, and interfacial behavior was analyzed under various thermodynamic conditions. The results show that increasing temperature (298–500 K) and pressure (0–10 MPa) significantly enhances interfacial atomic diffusion, as indicated by steeper MSD curves, higher diffusion coefficients, and a reduction in the height of the main peak in the radial distribution function. In addition, the atomic number distribution analysis reveals enhanced overlap and intermixing among different species under elevated temperature and pressure, confirming progressive densification of the interfacial region. Further increasing the pressure to 15 MPa suppresses this diffusion behavior. Ta atoms exhibit a higher diffusion capacity than Au atoms, promoting a faster bonding process. The AuTa interface displays the highest degree of atomic disorder, indicating favorable bonding characteristics. These findings reveal the atomistic diffusion- assisted bonding mechanism in GaN–diamond heterostructures and provide theoretical guidance for optimizing bonding parameters and improving thermal management in next-generation power electronic devices. © 2025 Elsevier B.V.