Mobility Enhancement In Crystalline In-Ga-Zn-Oxide With In-Rich Compositions

The electron mobility of In-Ga-Zn-oxide (IGZO) is known to be enhanced by higher In content. We theoretically investigated the mobility-enhancement mechanism by proposing an In-Ga-Zn-disorder scattering model for an In-rich crystalline IGZO (In1+xGa1-xO3(ZnO)(m) (0 < x < 1, m > 0)) thin film. The obtained theoretical mobility was found to be in agreement with experimental Hall mobility for a crystalline In1.5Ga0.5O3(ZnO) (or In3GaZn2O8) thin film. The mechanism specific to In-rich crystalline IGZO thin films is based on three types of Coulomb scattering potentials that originate from effective valence differences. In this study, the In-Ga-Zn-disorder scattering model indicates that the effective valence of the In3+ ions in In-rich crystalline IGZO thin films significantly affects their electron mobility. (C) 2015 AIP Publishing LLC.