Point defects (vacancies, interstitial atoms) were deliberately introduced in situ during layer growth. Two techniques were used to generate point defects during molecular beam epitaxy. One was bombardment of the growth surface with Si+ ions, and the other was epitaxy at very low temperatures. It was observed that lowering the temperature during the pseudomorphic growth of SiGe on Si(001) substrates substantially affected the relaxation of coherency stresses. Relaxation began at smaller thicknesses of the epilayer, and the morphology of both misfit dislocations and threading dislocations in the epilayer differed from the morphology which was observed after conventional high-temperature growth. This demonstrated that a low-temperature step in the early stages of epitaxial growth was an effective means for affecting the formation of extended defects in SiGe layers over a wide range of compositions. The observed effects arose from interactions between dislocations and point defects.

Interaction between Point Defects and Dislocations in SiGe K.Lyutovich, F.Ernst, E.Kasper, M.Bauer, M.Oehme: Solid State Phenomena, 1999, 69-70, 179-84