First-principles calculations of native defects in tin monoxide

The formation energies and electronic structure of native defects in tin monoxide are investigated by first-principles calculations. Equilibrium defect concentrations, which are obtained using the calculated formation energies and charge neutrality, indicate that the tin vacancy is the dominant defect under oxygen-rich conditions. It forms shallow acceptor states, suggesting that the p-type conductivity of tin monoxide originates from the tin vacancy. The equilibrium concentration of the oxygen interstitial is comparable with the tin vacancy at elevated temperatures. However, it is hardly ionized and therefore not expected to contribute to the conductivity. The concentrations of donorlike defects such as the tin interstitial and the oxygen vacancy are low enough not to compensate holes generated by the tin vacancy.