Crystalline In–Ga–Zn–O Density of States and Energy Band Structure Calculation Using Density Function Theory

The density of states (DOS) and energy band structure of crystalline In–Ga–Zn–O (c-IGZO) and the impact of point defects on its electronic structure are investigated by first-principles calculations based on the density function theory. The calculated DOS showed that the p-orbitals of the oxygen atoms mostly contribute to the valance band maximum (VBM) of c-IGZO. The conduction band minimum (CBM) is dominated by s-orbitals of the Zn/Ga mixture atoms, while the In atoms have the largest spatial spread of wave function. Oxygen vacancies create fully occupied defect states within the band gap and serve as deep donors. Both hydrogen substitutions and interstitials act like shallow donors, and raise the Fermi level above the CBM. Oxygen split interstitials created fully occupied defect states above VBM, while oxygen octahedral interstitials create both occupied and unoccupied states, and may serve as acceptors.