Electron–phonon coupling and electron mobility in degenerately doped oxides from first-principles

Abstract

Recent developments in growing highly n-doped wide bandgap oxides such as β-gallium oxide (β − Ga2O3) and more recently zinc gallate (ZnGa2O4) have opened avenues toward important applications, such as transparent electrodes and ohmic contacts. Magnetoconductivity measurements provide a unique method to assess the contribution of phonons to mobility over a wide range of temperatures. For β − Ga2O3 and ZnGa2O4, initial attempts to interpret the measured magnetoconductivity raised fundamental questions about the interplay between the large number of phonon modes in these lattices, electron–phonon scattering, and lattice disorder. Here, we use density functional theory modeling of electron–phonon scattering to help rationalize magnetoconductivity measurements for a wide range of electron concentrations n and temperatures in β − Ga2O3 and ZnGa2O4. The results provide a first-principles understanding of dominant low-field mobility features suggested by phenomenological models used traditionally for semiconductors with high lattice symmetry.