Glancing-angle ion enhanced surface diffusion on GaAs(001) during molecular beam epitaxy

We describe the effects of glancing incidence 3-4 keV Ar ion bombardment on homoepitaxial growth on vicinal GaAs(001). The average adatom lifetime on surface terraces, measured during growth using specular ion scattering, dec reased monotonically with increasing ion current density. The results indic ated that surface diffusivity was increased by the ions. The ion beam also suppressed growth oscillations and decreased the film surface roughness. Th is indicates a change from two-dimensional island nucleation to step-flow g rowth due to increased adatom surface diffusivity. A simple model, involvin g direct momentum transfer from ions to adatoms, is shown to be consistent with the measured enhanced diffusion.