Microscopic Origin of Universal Quasilinear Band Structures of Transparent Conducting Oxides

Abstract: We provide a tight-binding model that applies to the conduction bands of most transparent conducting oxides in both crystalline or amorphous structures. It is found that the often ignored interaction between O p and metal s orbtials plays a critical role in determining the dispersion relation of the conduction bands, which is that of the massive Dirac particles. The conditions for the local geometries enable this universal band structure were identified and they are well satisfied in most TCOs, even in amorphous structures. The impact of the peculiar band structure will be demonstrated for the electronic mobility of ZnO.