Non-stoichiometry and electronic properties of GaAs(100) surfaces thermally cleaned in ultrahigh vacuum

Auger electron spectroscopy and photoemission yield spectroscopy were used in the investigation of the n-type GaAs(100) surface annealed in ultrahigh vacuum. The influence of the annealing temperature both on surface composition (non-stoichiometry) and on the surface band structure parameters together with the effective density of filled electronic states localized in the band gap and in the upper part of the valence band were determined. Correlations are found between the non-stoichiometry of the surface composition and the surface band structure parameters of the n-type GaAs(100) surface annealed in ultrahigh vacuum. The origin of the observed electronic surface states bands localized in the band gap and in the upper part of the valence band is briefly discussed.