The energy change which occurred upon introducing a misfit dislocation into an epitaxially strained semiconductor stripe of height, h, and width, 2l, was estimated for dislocations which were parallel to the stripe direction (longitudinal) or across the stripe direction (transverse). The stress distribution in the stripe (in the absence of dislocations) was calculated by using a finite-element method. This predicted much lower normal stresses than those which had been predicted by using earlier analytical models. These lower stresses resulted in a greater stability of the film with regard to the introduction of a longitudinal dislocation. Thus, the critical misfit strain for the introduction of a longitudinal dislocation into a stripe (with h/l = 1) was over 5 times higher than that for a film of infinite lateral extent. On the other hand, the stress parallel to the stripe was not greatly affected, and therefore the critical misfit strain for the introduction of a transverse dislocation was approximately equal to that for an infinite film. The predictions were in reasonable agreement with experimental data for SiGe films which had been grown onto Si mesa stripes.
Stability of Dislocations in Epitaxially Strained Semiconductor Stripe Films. A.Atkinson, K.Pinardi, S.C.Jain: Semiconductor Science and Technology, 1996, 11, 1271-5