Diffusion of Arsenic in GaAs Oxide Irradiated with Ar⁺ Ions

Abstract—

A number of mechanisms of the diffusion of arsenic atoms including the radiation- stimulated vacancy, interstitial, and mixed (Frank—Turnbull mechanism) types are considered to explain the earlier discovered ion-stimulated transformation of a layer of native GaAs oxide into a layer of Ga₂O₃ at room temperature. An estimate of the diffusion coefficients and lengths makes it possible to conclude that the interstitial diffusion mechanism dominates at a fluence Q < 10¹⁵ cm^–2. It is found that at room temperature, when the interstitial mechanism is implemented, the diffusion coefficient (D_As ~ 1.3 × 10^–16 cm²/s) and the diffusion length (L > 9 nm) are sufficient to remove elemental arsenic formed under the action of argon ions from a layer of native oxide with a thickness of 2.0–2.5 nm in 10 minutes. However, the contribution of the vacancy mechanism increases with increasing irradiation dose due to an increase in the concentration of vacancies. In this case, the diffusion mechanism becomes mixed. At a fluence of Q > 10¹⁵ cm^–2, the vacancy mechanism provides a diffusion coefficient (D_As ~ 0.7 × 10^–17 cm²/s) and diffusion length (L > 2.5 nm) also sufficient to remove elemental arsenic from the oxide layer within 10–20 min. It is shown that the diffusion of arsenic can be significant in the processes of chemical modification of GaAs oxides even at room temperature.