Origin of electronic and optical trends in ternaryIn2O3(ZnO)ntransparent conducting oxides(n=1,3,5): Hybrid density functional theory calculations

Abstract

Ternary oxides formed from zinc and indium have demonstrated potential for commercial optoelectronic applications. We present state-of-the-art hybrid density functional theory calculations for Zn-poor and Zn-rich compositions of the crystalline ${\text{In}}_{2}{\text{O}}_{3}{(\text{ZnO})}_{n}$ compounds. We reveal the origin of the redshift in optical transitions compared to the two component oxides: symmetry forbidden band-edge transitions in ${\text{In}}_{2}{\text{O}}_{3}$ are overcome on formation of the superlattices, with Zn-O contributions to the top of the valence band. Increasing $n$ results in the localization of the conduction-band minimum on the In-O networks. This enhanced localization explains why Zn-poor compounds (lower $n$) exhibit optimal conductivity.