First-principles Study of the Electronic Structure of Crystalline InGaO3(ZnO)(3)

Abstract

Using first-principles density functional calculations, we study the energetics of various configurations of the Ga atoms in the (GaZn3)O-4 layers of InGaO3(ZnO)(3). We find that a diffused boundary structure, where the Ga atoms are distributed in two central layers of the Ga/Zn-O block, is energetically more favorable than sharp boundary and modulated boundary structures, where the Ga atoms form single flat and zigzag-like boundaries, respectively. The valence band maximum state is associated with the Zn-O bonds and is significantly modified by the distribution of the Ga atoms, while the conduction band edge characterized by the metal s orbitals is less affected. The band gaps are found to be direct for the sharp boundary and diffused boundary structures whereas an indirect band gap appears in the modulated boundary structure.