Evaluation of relaxation and misfit dislocation blocking in strained silicon on virtual substrates

Relaxation of strained silicon on 20% linear graded virtual substrates has been quantified using a dilute Schimmel etchant to reveal dislocation content, and high-resolution X-ray diffraction. The thickness of strained silicon investigated ranged from 10-180 nm. Low levels of relaxation were observed in layers below the Matthews and Blakeslee critical thickness, increasing up to about 2% relaxation for the largest layer thickness. Stacking faults were observed in all but the 10 nm layer, as confirmed by cross-sectional transmission electron microscopy. Impediments to dislocation glide by misfit dislocations and stacking faults were quantified and offered as an explanation for the limited degree of relaxation observed. (c) 2008 Published by Elsevier B.V