First-principle study of electronic structure of Sn-doped amorphous In2O3 and the role of O-deficiency

Through the first-principle calculations, we investigate the electronic structure of Sn-doped amorphous In2O3 (a-ITO), whose structures were obtained from the melting-and-quenching process using the ab initio molecular dynamics (MD) simulations. According to the analysis of the short-range ording, it is found that various sub-structures are mixed, differently from the crystalline structure. Inverse participation ratio (IPR) analysis of the wavefunctions indicates that the states around the conduction band edges (CBE) are well delocalized, i.e., only slightly changed from those of crystalline In2O3:Sn. However, the serious localized states are developed near the valence band (VB) in the a-ITO. Even by the O-deficiency, the character of the CBE is little changed, but the localization around VB is enhanced, which leads to the band-gap narrowing.