Crosshatching on a SiGe film grown on a Si(001) substrate studied by Raman mapping and atomic force microscopy

The morphology, stress, and composition distributions of the crosshatch pattern on a SiGe film grown on a Si(001) substrate using a low-temperature Si buffer are studied by atomic force and Raman microscopies. Crosshatching is not related to composition fluctuation regardless of the stress undulation associated with strain relaxation in the SiGe film. The crosshatch morphology arises from vertical lattice relaxation induced by piled-up misfit dislocations in the Si buffer layer and substrate. A model for crosshatch formation is proposed.