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.