Electronic band structure of indium tin oxide and criteria for transparent conducting behavior

Indium-based transparent conductors, notably indium tin oxide (ITO), have a wide range of applications due to a unique combination of visible light transparency and modest conductivity. A fundamental understanding of such an unusual combination of properties is strongly motivated by the great demand for materials with improved transparent conducting properties. Here we formulate conditions for transparent conducting behavior on the basis of the local density full-potential linear muffin-tin orbital electronic band structure calculations for Sn-doped In₂O₃ and available experimental data. We conclude that the position, dispersion, and character of the lowest conduction band are the key characteristics of the band structure responsible for its electro-optical properties. Further, we find that this lowest band is split with Sn doping due to the strong hybridization with dopant s-type states and this splitting contributes to both the decrease of the plasma frequency and the mobility of the carriers.