An electron-phonon Monte Carlo study on thermal transport in GaN

Heat conduction in micro/nano-scale materials are well modeled by Boltzmann transport equation (BTE) and the Monte Carlo (MC) method is an effective computational tool for solving BTE. In conventional insulators and semiconductors, phonons are the majority heat carriers and contribution of electron-phonon interaction (EPI) is negligible. However, in polar semiconductors electron-phonon interaction and its contribution to thermal conductivity are significantly high. In this paper, we develop a novel MC scheme which combines phonon and electron transport effectively to address electron-phonon interaction (EPI). The method is applied in a case study, simulating the thermal transport in wurtzite Gallium Nitride (GaN), considering the EPI impact into account. Deformation potential as well as polar optical potential (POP) are used to characterize EPI. Individual scattering rates of electrons are first determined. Using them the net scattering rate and relaxation times are calculated. Both lattice temperature and the electron temperature profiles in the computational domain are estimated and compared. The final inference is that the lattice thermal conductivity of wurtzite GaN at room temperature is found to be reduced by 16%-22%, on incorporating EPI, for samples of varying thicknesses.