EFFECTS OF DOPING ON THE ELECTRONIC-STRUCTURE OF LAXSR1-XTIO3

The effect of doping electrons on the electronic structure of single-c rystalline LaxSr1-xTiO3 samples (x = 0.001, 0.01, 0.05) has been studi ed for the fractured surface by photoemission spectroscopy. Two peaks in the band gap region of SrTiO3 (in-gap peaks) are induced by La subs titution for Sr: a peak with a sharp Fermi cut-off(metallic peak) and a broad peak centered at similar to 1.5 eV below the Fermi level (simi lar to 1.5 eV peak). The spectral intensity of the metallic peak and t he similar to 1.5 eV peak increase with the carrier concentration, but the spectral width of the metallic peak does not depend upon it. The behaviors of doping electrons on the electronic structure near the Fer mi level of LaxSr1-xTiO3, such as no change in the spectral width of t he metallic peak and the appearance of the similar to 1.5 eV peak, can not be simply explained by the band theory. (C) 1997 Academic Press Li mited.