First-Principles Study of the Electronic Structure of Single-Crystalline InGaZnO4

Through first-principles calculations, we investigate the electronic structures of single crystals of InGaZnO4 (sc-InGaZnO4), which have a complex structure consisting of InO2 layers inter-stacked with GaZnO2 double layers. Within the GaZnO2 layers, Zn and Ga atoms alternatively occupy the cation sites. We find that the conduction band of the sc-InGaZnO4 is composed of the hybridization of In-s, Ga-s, Zn-s and O-p orbitals while the valence bands are characterized dominantly by O-p orbitals. At the conduction band, the energy of In-s band are lower than those of Ga and Zn atoms the Ga-driven states are slightly lower than Zn-driven states, and the band widths of the Zn- and Ga-driven bands are wider than that of the In-driven band.