Polaron character of the near-E sub(F) band of cleaved In sub(2) O sub(3)(111) single crystals

The near-E sub(F) band of the in situ cleaved (111) surface of high-quality n-type In sub(2) O sub(3) single crystals was investigated by high-resolution angle-resolved photoemission (ARPES) along the major symmetry lines of the three-dimensional Brillouin zone. Several criteria to pin down Fermi level crossings and Fermi momenta were applied. The near-E sub(F) band is of three-dimensional character connected to the bottom of the conduction band. Since the model of a degenerate semiconductor due to high n-type doping (n=1.8 x10 super(18) cm super(-3) is not sufficient the interaction of electron and phonon degrees of freedom is discussed. It is found that the model of Landau-Pekar polarons is capable of describing the observed lineshape qualitatively and the bandwidth of the occupied part of the conduction band quantitatively.