Evolution and coarsening of Si-rich SiGe islands epitaxially grown at high temperatures on Si(001)

In this work we investigate by means of atomic force microscopy in combination with selective wet etching experiments coalescence and coarsening effects on the morphology evolution of Si-rich SiGe quantum dots and islands grown epitaxially at high temperatures on Si(001) substrates. We demonstrate that under certain growth conditions remarkably uniform island size distributions can be achieved for dome and cupola islands, while the morphological transition is dominated by coarsening and coalescence effects similar to Ostwald ripening. Under further deposition the uniformly sized cupola islands transform into larger islands with even steeper side facets (>80 degrees). The footprints obtained from selective wet etching experiments performed on the merging islands reveal that basically all atoms of the two islands are involved in the coarsening process. (C) 2013 Elsevier B.V. All rights reserved.