The electronic and optical properties of carbon-doped SrTiO3: Density functional characterization

The electronic properties and optical activities of C-doped cubic SrTiO3 in perovskite structure are studied by first-principles calculation. The calculated formation energies show that the substitutional C impurity is preferentially occupied at the Ti site. For C@O, the C impurity introduces spin-polarized gap states, and the associated electron excitations among the valence band, the conduction band and the gap states produce various visible-light absorption thresholds. For C@Ti, some C gap states of s-character appear near the bottom of the conduction band, which result in the lowered optical transition energy and thus the visible light absorption as observed in the experiment. Copyright 2012 Author(s). This article is distributed under a Creative Commons Attribution 3.0 Unported License. [http://dx.doi.org/10.1063/1.4746023]