Refractive index dispersion in thin ZnGa2O4 films

We have studied refractive index dispersion in thin ZnGa2O4 films obtained by high-frequency RF ion plasma sputtering. We have established that the spectral dependence of the refractive index in the visible region of the spectrum is mainly determined by transitions from the band including 2p states of the oxygen and 3d states of the zinc, forming the highest occupied level of the valance band, to the bottom of the conduction band formed by the 4s4p states of the zinc. For the studied films, we have determined the parameters of the single-oscillator approximation, the dispersion energy, the chemical bond ionicity, and the coordination number.