Distinctions in the Ge wetting layer formation and self-assembled island nucleation between single- and multilayer SiGe/Si(0 0 1) structures

The features of island nucleation in multilayer SiGe structures were investigated experimentally, revealing differences in the wetting layer formation between single- and multilayer structures. A significant redistribution of the wetting layer material caused by the inhomogeneous strain fields produced by the buried islands of underlying layers, which leads to the formation of “hills”, was found out. It was observed that these hills are the preferable sites for the islands nucleation in the upper layers. The pathway of island formation via the faceting of the hill’s sides was revealed.