Molecular dynamics study on phonon heat transport characteristics of interlayer regulated GaN/diamond interface

High-power GaN electronics suffer severe thermal bottlenecks originating from large thermal boundary resistance at GaN/diamond heterointerfaces. Here we employ non-equilibrium molecular dynamics simulations to systematically probe interfacial heat transfer modulated by interlayers. We quantify thermal boundary resistance across a matrix of control variables: interlayer type, interlayer thickness, vacancy defect distribution, and temperature, and interpret the underlying phonon transport mechanisms via phonon density of states and phonon participation ratio analyses. The results reveal that amorphous silicon delivers superior phonon spectral matching between GaN and diamond, which substantially suppresses thermal boundary resistance, thinner amorphous silicon interlayers further improve cross-interface heat dissipation. Uniform low-concentration vacancies embedded uniformly within the amorphous silicon interlayers induce only mild thermal boundary resistance elevation, yet vacancy agglomeration adjacent to heterointerface drastically amplifies thermal boundary resistance. We additionally observe a negative correlation between temperature and the overall thermal boundary resistance of GaN/interlayer/diamond interface. This work establishes atomic-scale mechanistic insights to guide heterointerface design for thermal management of next-generation GaN power devices integrated with diamond substrates.