Strain induced stabilization of stepped Si and Ge surfaces near „001..

We report on calculations of the formation energies of several @100# and @110# oriented step structures on biaxially stressed Si and Ge ~001! surfaces. It is shown that a novel rebonded @100# oriented single-height step is strongly stabilized by compressive strain compared to most well-known step structures. We propose that the side walls of ‘‘hut’’-shaped quantum dots observed in recent experiments on SiGe/Si films are made up of these steps. Our calculations provide an explanation for the nucleationless growth of shallow mounds, with steps along the @100# and @110# directions in lowand high-misfit films, respectively, and for the stability of the ~105! facets under compressive strain. © 2002 American Institute of Physics. @DOI: 10.1063/1.1491611#