Interaction between point defects and dislocations in SiGe

Aiming to reduce the threading dislocation density and to improve the surface smoothness of thin SiGe buffer layers grown on Si (001) substrates by molecular beam epitaxy (MBE), we deliberately introduce point defects (vacancies or interstitial atoms) in situ - during layer growth. To generate point defects during MBE we pursue two separate techniques, both applied during the stages of both, stable and metastable pseudomorphic growth: (i) bombardment of the growth surface with Sif ions and (ii) epitaxy at very low temperature. This paper reports about first results we have obtained by epitaxy at low temperature.