Resonant Ta Doping for Enhanced Mobility in Transparent Conducting SnO.

Transparent conducting oxides (TCOs) are ubiquitous in modern consumer electronics. SnO is an earth abundant, cheaper alternative to InO as a TCO. However, its performance in terms of mobilities and conductivities lags behind that of InO. On the basis of the recent discovery of mobility and conductivity enhancements in InO from resonant dopants, we use a combination of state-of-the-art hybrid density functional theory calculations, high resolution photoelectron spectroscopy, and semiconductor statistics modeling to understand what is the optimal dopant to maximize performance of SnO-based TCOs. We demonstrate that Ta is the optimal dopant for high performance SnO, as it is a resonant dopant which is readily incorporated into SnO with the Ta 5d states sitting ∼1.4 eV above the conduction band minimum. Experimentally, the band edge electron effective mass of Ta doped SnO was shown to be 0.23 , compared to 0.29 seen with conventional Sb doping, explaining its ability to yield higher mobilities and conductivities.