The dependences of the lattice structure and surface morphology of SiGe/graded buffer/Si(110) heterostructures on substrate temperature during gas-source molecular beam epitaxy (MBE) were investigated by X-ray diffraction (XRD) measurement and atomic force microscopy (AFM). Structural features and surface morphology depend strongly on the substrate temperature. A mosaic structure was formed at around 700 degrees C. Above 700 degrees C, the diffraction peak from SiGe layer split. The dependence of the crystal structure on GeH4 flow rate during film growth was investigated, and it was confirmed that the emergence of the mosaic structure and the rearrangement of the lattice structure can be attributed mainly to thermal effects. (c) 2006 Elsevier B.V. All rights reserved.