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

The strain relaxation of pseudomorphic Si1-xGex layers (x=0.21,...,0.33) was investigated after low-dose Si+ ion implantation and annealing. The layers were grown by molecular-beam epitaxy or chemical vapor deposition on Si(100) or silicon-on-insulator. Strain relaxation of up to 75% of the initial strain was observed at temperatures as low as 850 degreesC after implantation of Si ions with doses below 2x10(14) cm(-2). We suggest that the Si implantation generates primarily 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 doses of 1-2x10(16) cm(-2). (C) 2004 American Institute of Physics

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

Microstructure evolution effects of helium redistribution in as-implanted silicon and Si0.8Ge0.2/Si heterostructures

Elastic recoil detection (ERD), Rutherford backscattering/channeling spectrometry (RBS/C) and transmission electron microscopy (TEM) techniques are applied to study the retention of ion implanted He atoms in Cz (1 0 0) Si wafers. The implantations were performed at room temperature using energies from 5 to 60 keV and fluences within 1 to 4 x 10(16) cm(-2). The retained fraction of He decreases from 100% at 60 keV to approximate to5% at 15 keV. The retained He fraction is independent of the implanted fluence, of the accumulated lattice damage, and/or of the presence of TEM observable bubbles. Pure thermal diffusion cannot explain the present results which are applied to improve the strain relaxation of pseudomorphic SiGe/Si (1 0 0) ultra thin buffer layers with low threading dislocation densities. (C) 2004 Elsevier B.V. All rights reserved