The effect of ion implantation into molecular beam grown, strained Si/Si0.8Ge0.2 layers and Si/Si0.5Ge0.5 superlattices has been investigated by He ion channeling and transmission electron microscopy. Si implantation with energies of 750 keV at about 240° C in Si/Si0.8Ge0.2 layers led to gradual strain relaxation with increasing dose. The layers remained single crystalline even up to doses of 1 × 1016 Si/cm2. Planar dechanneling results indicated the formation of dislocations. Experimentally determined dislocation spacings were compared with theoretical estimates based on van der Merwe's model, assuming strain relaxation by the formation of misfit dislocations. A five period Si/Si0.5Ge0.5 superlattice appeared to be much more sensitive to ion bombardment. Implantation of 1 × 1016 Si/cm2 led to a nearly complete collapse of the single crystalline structure.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics