Theoretical and experimental investigation of the electronic properties of the wide band-gap transparent semiconductor MgGa2O4

We present an experimental and theoretical study of the electronic structure of the transparent conductive oxide semiconductor ${\mathrm{MgGa}}_{2}{\mathrm{O}}_{4}$. Its valence band and the core levels have been measured experimentally by angle-resolved photoemission spectroscopy and compared to theoretical ab initio density-functional calculations. The bands stem from oxygen orbitals and have a dispersion of about 0.6 eV and high effective masses, in agreement with the calculations. Angle-resolved measurements of the Ga 3d core levels indicate a sizable upward band bending, which in combination with an exact model potential yielded a quantitative estimate of the spatial extension of the depletion region, the effective Debye length in the material, and the extrinsic bulk carrier density.