Strain relaxation of pseudomorphic Si1-xGex/Si(100) heterostructures by Si+ ion implantation

Strain relaxation of pseudomorphic Si1-xGex layers (x = 0.21-0.33) grown by chemical vapor deposition or molecular-beam epitaxy on Si(1 0 0) or silicon-on-insulator was investigated after low-fluence Si+ ion implantation and annealing. Strain relaxation of up to 75% of the initial pseudomorphic strain was observed at temperatures as low as 850 degrees C after implantation of Si+ ions with fluences below 2 x 10(14) cm(-2). We suggest that the Si implantation generates a high density of dislocation loops in the SiGe layer and in the underlying Si, which convert to strain relaxing misfit segments. The obtained results are comparable to strain relaxation achieved after He+ implantation with fluences of 0.7-2 x 10(16) cm(-2). (c) 2005 Elsevier B.V. All rights reserved.