Thermal conductivity and temperature-induced bandgap renormalization in crystalline and amorphous Ga2O3

Abstract

The lattice thermal conductivity (LTC) and electron–phonon interactions in crystalline and amorphous gallium oxide are herein determined by coupling a machine-learned interatomic potential, namely the moment tensor potential model, to first-principles calculations. Crystalline β-Ga2O3 exhibits a substantial bandgap renormalization (BGR) of ∼0.45 eV at 700 K, with ∼0.2 eV caused by zero-point BGR. The computed temperature dependence of BGR induced by classical nuclear motion in β-Ga2O3 is stronger than that in amorphous Ga2O3, with the difference in BGR reaching ∼0.18 eV at 900 K. Thermal transport calculations reveal that the LTC of amorphous Ga2O3 remains near 0.9 W m−1 K−1 for temperatures between 300 and 700 K, which is approximately an order of magnitude lower than that of crystalline β-Ga2O3. Overall, the presented framework provides a computationally tractable and reliable route for predicting properties of semiconductors (both crystalline and amorphous) under operating conditions relevant to microelectronics and optoelectronics.