Analysis of the oxygen vacancy induced metallic state in SrTiO3

Strontium titanate (SrTiO3) is one of the typical perovskite oxides and has been considered for use in oxide electronics. Recently, high carrier mobilities on the fractured bare (001) surface have been found, and the source of the 2D electron gas (2DEG) at the surface is still not clear. Oxygen vacancies are assumed to be one of the origins for the conductivity. By using density function theory (DFT), we investigate the electronic structure of SrTiO3 surfaces in the presence of different oxygen vacancy concentrations both in SrO and in TiO2 terminated (001) slabs. We find that the conductivity is caused by the extra electrons due to the oxygen vacancy which are transferred to Ti 3d states. In this talk we discuss our results in comparison with available experimental measurements.