Wave-like periodic structures on the silicon surface initiated by irradiation with a focused gallium ion beam

The processes of microrelief formation on the Si(100) surface under irradiation with a 30 keV Ga+ ion beam and a fluence of D = 1.25 × 1018–2 × 1019 cm–2 at incidence angles θ = 30°–85° was investigated. It was found that in the θ angular range 40°–70° faceted ripples were formed on the Si surface, and at θ = 30° sinusoidal ripples were formed. The experimental dependence of the wavelength of the periodic structure on the irradiation time λ(t) ~ tn, n = 0.33–0.35, was obtained. The average velocities of relief propagation and their direction relative to the direction of incident ions in the cases of θ = 30° and 40° were determined, which were –5.3 ± 0.6 and –6.3 ± 0.6 nm/s, respectively. The results obtained are discussed in detail within the framework of existing models of the formation of ripples on a surface under ion beam irradiation.