Strain-induced formation of self-assembled nanostructures grown under kinetically limited conditions in the SiGe/Si epitaxial system

Epitaxial growth of Si _0.7 Ge _0.3 /Si(001) under kinetically limited conditions results in the initial formation of shallow pyramidal pits with {501} facets, similar to an inverted “hut” structure. As growth is continued, the pit edges become decorated by islands that elongate to form a continuous wall surrounding each pit. These “quantum fortress” structures reach a maximum stable size. The quantum fortress morphology becomes de-stabilized by further growth causing the introduction of dislocations and also by annealing at temperatures above the growth temperature. The surface morphology has been characterized using both atomic force microscopy and transmission electron microscopy.