Si growth on partially relaxed Ge islands

Abstract
We use low-energy electron microscopy (LEEM) to study Si growth on {105} faceted Ge islands on Si (100). A quantitative analysis of LEEM growth sequences suggests, that for low Si coverage no growth occurs at the island apex, and that adatoms in the apex region are collected onto the {105} side facets. This “partial wetting” growth mode leads to a characteristic formation of a large (100) plane bounding the top of the islands. We find Ge surface segregation on the {105} facets to play an important role in the overgrowth process: Ge/Si intermixing leads to a stabilization of the facet structure over a large range of Si coverage and results in a shape of buried islands mapping their morphology during overgrowth: a truncated pyramid, bounded on top by a (100) plane.