Misfit dislocations in annealed Si 1− xGe x/Si heterostructures

Abstract

Strained Si 1− x Ge x layers deposited on Si (001) substrates by molecular beam epitaxy (MBE) and cut into 1 cm square samples have been annealed at temperatures in the range 600–700 °C. Regions of crystalline damage present at the edge of the specimens were found to act as preferential sites for the nucleation of misfit dislocations. A dislocation front emanated from these sites during annealing, and the distance of the front from the sample edge was used to measure the glide velocity. Values of the glide activation energy ( E g) have been derived for a layer of Si 0.95Ge 0.05 (2.2±0.2 eV) 2.4 μm thick and for a layer of Si 0.87Ge 0.13 (2.2±0.3 eV) 0.5 μm thick. These results are compared with previously published data.