It was recalled that 1MeV ion bombardment of strained layers at high temperatures could cause strain relaxation. The defects which were responsible for relaxation, and for the evolution of the strain during subsequent annealing, were considered here. Three distinct annealing stages were identified and were related to the defect microstructure. At temperatures ranging from 350 to 600C, a gradual recovery of strain was observed. This was correlated with the annealing out of small defect clusters and the growth of voids. The voids were visible at annealing temperatures above 600C, and this was consistent with an excess vacancy concentration in the irradiated alloy layer. At temperatures of 600 to 750C, the strain recovered to a maximum value which was related to the ripening of voids, the dissolution of alloy-layer {113} rod-like defects, and to {113} planar interstitial defects in the substrate. At temperatures of 750 to 1000C, strain relaxation occurred and was correlated with the growth of intrinsic dislocations within the alloy layer. These loop-like dislocations nucleated at the alloy/substrate interface and grew within the alloy layer, towards the surface.

Strain and defect microstructure in ion-irradiated GeSi/Si strained layers J.M.Glasko, R.G.Elliman, J.Zou, D.J.H.Cockayne, J.D.FitzGerald: Applied Physics Letters, 1998, 73[6], 838-40