Patterns in Ge cluster growth on clean and oxidized Si(111)-(7 × 7) surfaces

Ge atoms have been deposited on domain-patterned clean Si(111)-(7 × 7) and oxidized Si(111)-(7 × 7) surfaces. Clustering of Ge from the deposited Ge adatoms on these two kinds of surfaces shows contrasting patterns. On the clean Si surface, clustering predominantly occurs on domain boundaries, which include step edges on two sides. This leaves small domains denuded. Ge diffusion length has been estimated from the size of these denuded domains. For large domains, additional clustering is observed within the domains. For the oxidized Si surface, the pattern formation is in sharp contrast with that for the clean Si surface. In this case the domain boundaries remain relatively empty and there is strong clustering within the domains leading to the formation of dense Ge nanoislands within the domains. This contrasting pattern formation has been explained via a reaction diffusion model.

► Ge adsorption and clustering on Si surfaces have been investigated. ► Some aspects of a theoretical reaction-diffusion model have been verified. ► On clean Si surfaces clustering predominantly occurs on step edges and domain boundaries. ► On an oxidized Si surface, clustering predominantly occurs within domains, leaving domain boundaries denuded. ► Diffusion length of Ge on Si surfaces has been determined.