Theoretical analysis of the electronic structure of pure and hydrated forms of As2O5

PASSEGGI (JR.), M.C.G.; VAQUILA, I.; SFERCO, S.J.

PHYSICAL REVIEW B - SOLID STATE

The American Physical Society

Lugar: New York, USA; Año: 1994 vol. 50 p. 2090 - 2094

0556-2805

The first stages of oxidation in GaAs(100) have been studied using Auger electron spectroscopy and principal component analysis. We found that at low oxygen exposures (<104 Langmuirs) and in the presence of excited oxygen produced by electron bombardment, GaAs oxidizes via a one-phase process only. This phase involves the simultaneous oxidation of both the elements Ga and As. A tight-binding method is applied to study the electronic structure of the orthorhombic and tetragonal phases of pure As2O5 as well as its hydrated crystalline compounds As2O5(5/3)H2O and As2O54H2O. From the calculated density of states we give the contribution of the atomic states to the x-ray photoemission valence-band spectrum. As atoms in tetrahedral environments exhibit a characteristic peak which is not found for As in octahedral coordination. In the case of hydrated oxides we predict a smaller valence-band width than in the pure oxides.