Stability and electronic properties of low-index surfaces of zinc stannate modulated by vacancy defect: A first-principle study

The low-index surfaces and defect structures of perovskite zinc stannate (ZTO) were studied based on the first-principles density functional theory (DFT) calculations. The geometry, stability and electronic properties of zinc stannate modulated by point defects were discussed. It is found that the 001 surface of ZTO and its oxygen defects on the surface were most stable thermodynamically among the 42 low-dimensional structures according to the energy calculations. The electronic properties near the Fermi level of low-dimensional ZTO structures can be modulated by different defects. This can be understood by electron band structure and density of states analysis. 101 surface of ZTO showed a metallic characteristic, while other low-dimensional ZTO structures were all semiconductors with a decreased band gap than that of the bulk. Defects could induce electron transfer and charge re-distribution on the ZTO surface by means of geometric and chemical bonding reconstruction on surfaces with defects.