The evolution of the He-implantation induced defect structure in SiGe/Si heterostructures was observed during in situ annealing at 650 and 800C within a transmission electron microscope. The He implantation and annealing resulted in the formation of He precipitates below the SiGe/Si interface, which at first showed a plate-like shape and subsequently decay into spherical bubbles. The coarsening mechanism of the He bubbles was revealed as coalescence via movement of entire bubbles. The nucleation of dislocation loops at over-pressurized He platelets and their propagation into the heterostructure could be observed as well. Distinctly different velocities of the dislocations were found, and attributed to glide and climb processes. The in situ experiments clearly showed that the He platelets acted as internal dislocation sources and played a key role in the relaxation of SiGe layers.

Evolution of the Defect Structure in Helium Implanted SiGe/Si Heterostructures Investigated by in situ Annealing in a Transmission Electron Microscope. N.Hueging, M.Luysberg, K.Urban, D.Buca, S.Mantl: Applied Physics Letters, 2005, 86[4], 042112 (3pp)