Observation of {105} facetted Ge pyramids inclined towards vicinal Si(001) surfaces

Abstract
Self-assembled Ge and SiGe islands, which are compact pyramids with four equivalent {105} facets, have been grown by molecular beam epitaxy on vicinal Si(001) surfaces with biatomic surface steps along the [110] direction. Revealed by atomic force microscopy, they appear as regularly facetted pyramids which are inclined by the miscut angles of 2.8° or 4° toward the sample surfaces and consequently have a distorted rhomb base. Characteristic patterns are observed by reflection high-energy electron diffraction from these facetted islands. They agree well with simulated patterns scattered by {105} facets. Avoiding elongated Ge hut clusters by using vicinal surfaces is promising for an improved homogeneity in island shape and size.