The effects of interruption time on the growth of Ge islands prepared by ion beam sputtering deposition

The growth interruption technique was employed to investigate the self-assembled growth of Ge islands prepared by ion beam sputtering deposition. The evolution of island size and density with the interruption time were well studied by atomic force microscopy. During the growth interruption process, Ostwald ripening induces a drastic decrease of the density of islands without capping. The distribution of these islands determines the further growth of Ge islands after depositing the second amount of Ge. For the interruption time below 60 s, the self-limiting growth of islands is significant, leading to a slight increase of island diameter and an obvious enlargement of island height with increasing the time. As the interruption time is more than 60 s, many new smaller islands form after depositing the second amount of Ge. Consequently, the density and the average aspect ratio of Ge islands remain stable. This is indicated that the growth of islands exhibits an equilibrium state between Ostwald ripening and the formation of new smaller islands. With an interruption time of 60 s, both island diameters and heights with an unimodal distribution are observed.