Electronic structure of p-type SrTiO3 by photoemission spectroscopy

The electronic structure of p-type SrTiO3 has been studied by photoemission spectroscopy (PES). Comparing with the PES of n-type SrTiO3, 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 SrTiO3, cannot be found in p-type SrTiO3. It is suggested that the band structure of p-type SrTiO3 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 SrTiO3 is much larger than that of n-type SrTiO3. Furthermore, it is also found that the satellite intensities of several core lines in p-type SrTiO3 are stronger than those in n-type SrTiO3. These facts suggest that the hybridization effect between the Ti 3d and O 2p states becomes stronger in p-type SrTiO3.