Effect of the Angle of Incidence of Low-Energy Ar⁺ Ion Beams on the Composition and Structure of the GaAs Surface

The effect of Ar⁺ ion bombardment with an energy of E₀ = 1 keV on the composition, structure, and band gap of GaAs is studied by Auger-electron- and light-absorption spectroscopy. The dependences of changes in the composition and electronic structure of GaAs surface layers on the dose D and angle of incidence φ (relative to the surface normal) of Ar⁺ ions are determined for the first time. It is shown that, at φ = 0, Ar⁺ ion bombardment at D = 5 × 10¹⁵ cm^‒2 leads to an increase in the As surface concentration relative to pure GaAs by up to 15–20 at % and, at D = 10¹⁷ cm^‒2, to its decrease by 12–15 at %. It is established that, at large angles of incidence (φ = 72°) of Ar⁺ ions, the Ga and As surface concentrations change insignificantly. The observed changes are explained.