Nucleation of Ge islands on Si mesas with high-index facets

In this paper, we report on the nucleation and growth behavior of nominally pure Ge islands when the deposition is being done on small pre-structured Si mesas. As these mesas with a lateral dimension ranging from 1 to 10 μm have been prepared using selective epitaxial growth, they exhibit different facets depending on the orientation of the mesa with respect to the Si substrate. As a result, Ge islands preferably nucleate on shallow-index facets as well as on (3 1 1) facets with steep edges. Contrary to this, no islanding has been observed on (9 1 1) facets. The preferential nucleation of the islands is being discussed with respect to the facet properties, i.e. the local step density and the strain anisotropy.