Vacancy Defect Modulated Interfacial Thermal Transport and Phonon Localization in AlGaN/GaN Heterojunctions

The AlGaN/GaN heterojunction is a key component of GaN-based high electron mobility transistors, where interfacial defects strongly influence heat dissipation. However, the mechanisms by which vacancy defects regulate interfacial phonon transport and localization remain unclear. Herein, nonequilibrium molecular dynamics (NEMD) combined with lattice dynamics analysis are employed to investigate the effects of vacancy defects on interfacial thermal transport in AlGaN/GaN heterojunctions. The results show that the interfacial thermal conductance (ITC) exhibits a nonmonotonic dependence on defect concentration, initially increasing and then decreasing. At a vacancy concentration of 0.5%, the ITC is enhanced by 9.15% and 5.72% for GaN- and AlGaN-side defects, respectively. With increasing defect concentration or defect ranges, phonon-vacancy and interfacial scattering are significantly strengthened, leading to pronounced phonon localization and suppression of effective heat-conduction channels. Furthermore, AlGaN exhibits higher sensitivity to defects, whereas defects on the GaN side are more effective in inducing cooperative phonon spectral reconstruction at high concentrations. By correlating defect characteristics with phonon transport behavior, this study reveals the dual regulatory role of vacancy defects in interfacial thermal transport and provides theoretical insights for defect engineering and thermal management in GaN-based electronic devices.