INTRINSIC AND EXTRINSIC SURFACE-STATES OF SINGLE-CRYSTALLINE SRTIO3

We have no evidence of intrinsic surface states in the band gap for in situ fractured SrTiO3:La, SrTiO3:Nb and SrTiO3. The valence band maxi mum of the samples lie at 3.3 eV below the Fermi level, indicating tha t the band bending is negligibly small. No emission from the region of bulk band gap indicated that the intrinsic surface states are largely empty. Ar+ ion bombardment of in sia fractured samples gave rise to a peak at around 11.6 eV, indicating the Ti+3 state. (C) 1998 American Institute of Physics. [S0021-8979(98)01016-0].