Electronic structure of electron doped SrTiO<SUB>3</SUB>: SrTiO<SUB>3−δ</SUB> and Sr<SUB>1−x</SUB>La<SUB>x</SUB>TiO<SUB>3</SUB>

Electronic structures of electron-doped SrTiO<SUB>3&#8722;&#948;</SUB> and Sr<SUB>1&#8722;x</SUB>La<SUB>x</SUB>TiO<SUB>3</SUB> have been investigated within the ab initio band-structure approach using a supercell containing eight basic units. A small amount of electron doping is found to drive SrTiO<SUB>3</SUB> metallic, with the Fermi level moving into the conduction band in both the systems. Clustering of oxygen vacancies in the case of SrTiO<SUB>3&#8722;&#948;</SUB> gives rise to distinct non-rigid-band-like evolution of the electronic structure, trapping doped charge carriers in midgap states; similar effects are not observed for Sr<SUB>1&#8722;x</SUB>La<SUB>x</SUB>TiO<SUB>3</SUB>, explaining the difference in the Hall measurements of these two closely related compounds