Features of Oxidation of Ar+-Ion-Irradiated GaAs

The features of oxidation of the surface of GaAs irradiated by low-energy Ar+ ions is considered based on elemental and chemical-composition analyses, calculations of the concentration profiles for radiation-induced defects, and estimations of radiation-enhanced diffusivities and diffusion lengths. The native oxide layer is revealed to be highly enriched with Ga (by a factor of 1.5) due to the radiation-enhanced diffusion of elemental arsenic through vacancy defects even at room temperature. Elemental arsenic emerging at the interface with the oxide layer moves to a deeper radiation-damaged layer and fills vacancies there. At irradiation doses of Q > 3 x 10(14) cm(-2), which are sufficient for removal of the oxide layer with 3-keV Ar+ ions, elemental arsenic leaves the oxide layer within one hour, and the diffusion length reaches the thickness of the radiation-damaged layer within one day. The total number of vacancies in the radiation-damaged layer is enough to absorb all elemental arsenic formed during oxidation. The considered radiation-enhanced diffusion can be used to remove elemental arsenic, which is known to form nonradiative recombination centers quenching the luminescence of the underlying bulk layer, from the oxide layer.