Strain relaxation of the epitaxial SiGe layer and Ge diffusion during nickel silicidation by rapid thermal annealing the structure of Ni(congruent to 14 nm)/cap-Si(congruent to 26 nm)/Si0.83Ge0.17/Si(001) at the elevated annealing temperatures, T-A, were investigated by X-ray diffraction analyses of high-resolution omega-20 scan and reciprocal space mapping. The analyses showed a much larger strain relaxation at a lower T-A and a reduction in Ge content in the SiGe layer of Ni/SiGe/Si(001) after thermal annealing compared to the case of cap-Si/SiGe/Si(001). The results indicate that the strain relaxation of the SiGe layers in NiSi/SiGe/Si(001) is related to the phenomena of NiSi agglomeration and penetration into the SiGe layer during silicidation at elevated anneal temperatures >= 750 degrees C. At elevated T-A >= 750 degrees C, Ge diffused into the intact cap-Si area during silicidation. (c) 2005 Elsevier B.V. All rights reserved.