Strain relaxation and threading dislocation density in helium-implanted and annealed Si _1-xGe _x/Si( 100) heterostructures

The investigation of strain relaxation and threading dislocation densities in Si 1-xGe x/Si(100) heterostructure produced by He implantation and annealing, using X-ray diffraction and transmission electron microscopy was discussed. It was observed that the degree of strain relaxation was very sensitive to the SiGe layer thickness. Small differences in strain relaxation were obtained when the lithium dose and energy were varied over a relatively wide range. It was shown that the threading dislocation density was strongly influenced by the implantation dose and depth.