The electronic properties of (100) surfaces after various treatments were studied by means of electron energy loss spectroscopy and Auger electron spectroscopy. It was found that a stoichiometric surface without contamination could be obtained by annealing at 910K, under an O atmosphere of 5 x 10-5Pa. A surface which was heated in ultra-high vacuum to 910K exhibited a new surface state, in the band-gap region, which arose from O vacancies in the upper Ti-O2 layer. This state was also produced by electron irradiation or Ar ion bombardment.

A.Hirata, A.Ando, K.Saiki, A.Koma: Surface Science, 1994, 310[1-3], 89-94