Energy dependence of quantum dot formation by ion sputtering

Ordered quantum dot patterns are generated on GaSb and InSb surfaces due to a surface instability induced by ${\mathrm{Ar}}^{+}$-ion sputtering at normal incidence. The characteristic length of the generated patterns scales with the square root of the ion energy over the energy range of 75–1800 eV. This energy dependence is compared to the solutions of the isotropic Kuramoto-Sivashinsky equation and allows the determination of the lateral width of the energy distribution deposited by the incident ions in the very-low-energy range. We show that the observed energy dependence is in agreement with the linear continuum theory under the assumption that the dominant smoothing process is due to effective ion-induced diffusion without mass transport on the surface.