We investigate the morphology and strain distribution of the surface crosshatch undulation on a strain-relaxed SiGe layer grown on a low-temperature Si buffer layer by atomic force microscopy and spatially-resolved UV-Raman spectroscopy. Surface crosshatch undulation resulted from misfit dislocations at the SiGe/Si interface is associated with the strain relaxation in the SiGe layer. By means of thermal annealing, strain relaxes and the inhomogeneous in-plane strain fluctuation can be eliminated. (c) 2008 Elsevier B.V. All rights reserved.