Electronic structure ofp-typeSrTiO3by photoemission spectroscopy

Abstract

The electronic structure of $p$-type ${\mathrm{SrTiO}}_3$ has been studied by photoemission spectroscopy (PES). Comparing with the PES of $n$-type ${\mathrm{SrTiO}}_3,$ the Fermi level of $p$ type is lower by about 0.7 eV and a prominent feature of Ti $3d$ character within the band gap, which is formed in the $n$-type ${\mathrm{SrTiO}}_3,$ cannot be found in $p$-type ${\mathrm{SrTiO}}_3.$ It is suggested that the band structure of $p$-type ${\mathrm{SrTiO}}_3$ follows the rigid-band model. The resonant photoemission study shows that the Ti $3d$ partial density of states in the valence band of $p$-type ${\mathrm{SrTiO}}_3$ is much larger than that of $n$-type ${\mathrm{SrTiO}}_3.$ Furthermore, it is also found that the satellite intensities of several core lines in $p$-type ${\mathrm{SrTiO}}_3$ are stronger than those in $n$-type ${\mathrm{SrTiO}}_3.$ These facts suggest that the hybridization effect between the Ti $3d$ and O $2p$ states becomes stronger in $p$-type ${\mathrm{SrTiO}}_3.$