Using compositionally graded SiGe films as virtual substrates, tensile-strained Si films with a strain of 1.5% and threading dislocation densities of less than 1.0 x 105/cm2 were grown in micron-sized windows by molecular beam epitaxy. The thickness of the virtual substrates was only 330nm. No cross-hatched lines resulting from misfit dislocations could be observed on the surface of the s-Si films. These results were attributed to edge-induced strain relaxation of the epitaxial films in windows, and patterned virtual substrates with compositionally graded SiGe films.

Highly Strained Si Films with Ultra-Low Dislocation Density Grown on Virtual Substrates of Thin Thickness. H.B.Yang, X.J.Zhang: Chinese Physics Letters, 2009, 26[4], 048103