THE CHEMISTRY OF O IN REDUCTION PROCESSES OF THE GAAS NATIVE OXIDES

We present an X-ray photoelectron spectroscopy (XPS) study of the interfacial chemical reactions during the total reduction of a 5 angstrom thick GaAs native oxide layer accomplished in two separate stages. First, the As2O3 has been selectively reduced by annealing the oxidized surface at increasing temperatures. In the second stage, the reduction of the Ga oxides has been completed at room temperature by Si deposition. The total amount of O at the GaAs interface remains constant during both processes. During the AS2O3 thermal reduction, the analysis of the Ga 2p3/2 and GaLMM spectra shows that, depending on the annealing temperature, GaOx (x < 3/2) or Ga2O3 growth occurs. The Si promoted reduction of the Ga oxides results in the formation of Si oxides of different stoichiometry at the GaAs surface.