Terrace Distribution During Sputtering and Recovery of InSb(110) Studied by He Atom Scattering

A helium-atom scattering experiment is reported on the evolution of vacancy islands produced by low-energy ion bombardment on InSb (110). It is seen that island growth occurs through dynamical scaling during the sputtering process, in agreement with the scaling hypothesis that is the basis of nucleation and growth models. After interruption of the sputtering, the spatial distribution of steps on the surface (strictly related to the island size and distance) gradually modifies during the self-organizing surface recovery. In this case the surface reduces its free energy by decreasing the step density; the corresponding increase of the terrace width occurs in the absence of free vacancy supersaturation and the process is diffusion limited. This change of the growth mechanism causes the breaking of dynamical scaling.