CONTROLLED MISFIT DISLOCATION NUCLEATION IN SI0.90GE0.10 EPITAXIAL LAYERS GROWN ON SI

Misfit dislocation formation has been controlled during growth at 500-degrees-C in strained, 720 nm Si0.90Ge0.10 on Si. The Si substrates were selectively Ge+ ion implanted and etched to form a series of mesas with stripes of implant damaged crystal. Misfit dislocations nucleated preferentially from the ion implanted regions during epitaxial layer growth, while other nucleation sources were inhibited by the low growth temperature and the etched trenches between mesas. Films were relaxed by as much as 35%. The epitaxial layers on some mesas were relaxed in essentially one [110] direction as well. Electron beam induced current images indicate that ion-implant activated misfit dislocations form before heterogeneous nucleation sources can operate, so that relaxation occurs in a more uniform manner.