Relaxation of strained pseudomorphic SixGe1-x layers on He-implanted Si/-Si:C/Si(100) substrates

In this letter we present a method to increase the efficiency of SiGe layer relaxation by He+ ion implantation and annealing. Preferential nucleation of He platelets along a delta-impurity layer grown in the Si substrate below the SiGe layer results in planar localization and homogenization of dislocation loop sources inducing a more uniform distribution of misfit dislocations. We demonstrate this for a thin Si: C layer grown by reduced pressure chemical vapor deposition. The optimization of the conditions for efficient relaxation and layer quality is studied with respect to the position of the Si: C layer and the process parameters. Relaxation degrees up to 85% are obtained for Si0.77Ge0.23 layers. (C) 2009 American Institute of Physics. [doi: 10.1063/1.3240409