The characteristic of strain relaxation on SiGe virtual substrate with thermal annealing

We report the effect of thermal annealing on the strain relaxation of SiGe virtual substrate. The results show that the strain of the SiGe layer relaxes anisotropically with thermal annealing through the formation of the misfit dislocations. The strain field fluctuation persists up to the annealing temperature of 1000 degrees C, suggesting that the in-plane strain fluctuation could be eliminated by thermal annealing process. In particular, from the analysis of spatially resolved ultraviolet Raman mapping, we found that the normal region relaxes with a faster rate than the crosshatch region as attributed to larger initial strain. (C) 2007 American Institute of Physics.