Effect of Al substitution on the electron-phonon interaction for β-Ga2O3

The relevant parameters of electron–phonon (e-ph) interaction, like mean phonon temperature and e-ph interaction strength for Al-substituted β-Ga2O3, i.e., β-(AlxGa1–x)2O3 alloys, have been determined from the fitting of the temperature dependence of the band gap using Bose–Einstein empirical model. Both e-ph interaction strength and mean phonon temperature decrease sharply for initial Al compositions; then, they increase slightly and become more or less constant. This is explained by using the already existed concepts of propagon and diffuson for the phonon modes that interact with the electrons. Presence of two sublattices at the local level is found to be the origin of diffuson-like behaviour of phonon modes in β-(AlxGa1–x)2O3 alloyed system, which vibrate independently like a non-propagating oscillator and diffuse through the β-(AlxGa1–x)2O3 lattice. The diffuson-like behaviour of phonon modes in the β-(AlxGa1–x)2O3 alloy is found to be responsible for the reduction in e-ph interaction. The reduction of e-ph interaction strength of β-Ga2O3 with Al substitution may lead to the better performance of power devices working at higher temperatures.