CHARACTERIZATION OF EXTENDED DEFECTS IN SIGE ALLOYS FORMED BY HIGH-DOSE GE+ IMPLANTATION INTO SI

The synthesis of SiGe/Si heterostructures by Ge+ ion implantation is r eported, 400 keV Ge+ ions were implanted at doses ranging from 3 x 10( 16) to 10 x 10(16) ions/cm(2) into (001) Si wafers, followed by Si+ am orphisation and low temperature Solid Phase Epitaxial Regrowth (SPER). TEM investigations show that strained alloys can be fabricated if the elastic strain energy (E(el)) of the SiGe layer does not exceed a cri tical value (E(el)') of about 300 mJ/m(2), which is independent of the implantation energy. Our analysis also suggests that ''hairpin'' disl ocations are formed as strain relieving defects in relaxed structures. A ''strain relaxation'' model is proposed to explain their formation.