关键词: 分子动力学, 键合, 界面扩散, 氮化镓, 金刚石

Abstract: To address the thermal dissipation bottleneck in gallium nitride (GaN) power devices and overcome the lattice and thermal mismatch challenges in GaN/diamond direct bonding, a GaN/Ta-Au-Ta/diamond structure is constructed based on molecular dynamics simulations. The interfacial bonding and atomic diffusion behaviors under varying temperatures and pressures are investigated. Atomic motion is analyzed through mean square displacement (MSD), diffusion coefficients, and radial distribution functions (RDF), while the interfacial densification characteristics are evaluated using the atomic density profile along the z-axis. The results indicate that as the temperature increases from 298 K to 500 K and the pressure rises from 0 MPa to 10 MPa, interfacial diffusion significantly intensifies, manifesting as an increased MSD slope, higher diffusion coefficients, and a reduction in the main peak of the RDF, along with deeper interfacial mixing. When the pressure further increases to 15 MPa, diffusion is suppressed. Ta atoms exhibit higher diffusion capability than Au, promoting faster interfacial densification, with the Au-Ta interface showing the highest degree of disorder and pronounced atomic mixing. The Ta-Au-Ta interlayer is found to enhance atomic diffusion at the GaN/diamond interface through an auxiliary bonding mechanism, providing a theoretical basis for optimizing bonding parameters and improving the thermal management performance of high-power devices.

Key words: molecular dynamics, bonding, interfacial diffusion, GaN, diamond