Multitemperature Modeling of Thermal Transport across a Au-GaN Interface from Ab Initio Calculations

With device dimensions shrinking toward nanoscale sizes, an accurate understanding and modeling of the thermal energy transfer mechanisms at metal-nonmetal interfaces becomes highly desirable. To model the thermal transport across the Au-GaN interface, we developed a general multitemperature model (MTM) that accounts for both electron and phonon transport and allows for a nonequilibrium phonon population described as a sum of thermal distributions of the phonon branches. The model is populated with material parameters computed from ab initio calculations and used to describe the temperature profile across a Au-GaN junction 400 nm in length subjected to constant temperature differential, continuous-wave laser heating of Au, and constant heat flux on GaN. The calculated steady-state and time-dependent temperature profiles reveal strongly nonequilibrium electron-phonon and phonon-phonon interfacial regions created through energy carrier coupling. Our results indicate that a multitemperature-based model is required for the accurate resolving of the thermal energy flow across metal-nonmetal interfaces. Our MTM will advance the theoretical tool to investigate nonequilibrium thermal transport across metal-nonmetal interfaces.