X-ray diffraction study of plastic relaxation in Ge-rich SiGe virtual substrates

We report on the experimental and theoretical investigation of the relaxation in Ge-rich SiGe/Ge/Si heterostructures. The experimental x-ray diffraction data are interpreted with the help of a model including both edge and 60 degrees misfit dislocations in the calculated x-ray scattering intensity. Our results show that highly positionally correlated edge dislocations dominate in the relaxation of the compressive strain at the Ge/Si interface, while a smaller tensile strain at the SiGe/Ge interfaces released by uncorrelated/little correlated 60 degrees dislocations.