Effect of La doping on the electronic structure of SrTiO3

For undoped-SrTiO3 and La-doped SrTiO3 single crystals, X-ray photoemission spectroscopy (XPS) measurements were performed with monochromated Al Ka ra diation. Valence band (VB) spectra of as-fractured SrTiO3 exhibit two peaks , Fl and P2, arising from the O 2p pi and O 2p sigma bonding orbitals, resp ectively. Upon adding 3.0 atm% of La to SrTiO3, the valley between P1 and P 2 disappears in the VB spectrum, Calculated VB spectra obtained from a mole cular orbital calculation reproduce well the experimental XPS spectra for t he samples.