We present the study of the thermal stability of SiGe virtual substrates with a thin Ge interlayer on Si substrate grown at low temperature. Thermal annealing under different temperatures was carried out, and the thermal stability of the virtual substrate was discussed in detail. From the investigation it is found that annealing could only affect the strain relaxation of the virtual substrate at 600 degrees C. When the sample is annealed at 800 degrees C, the structure of this virtual substrate becomes unstable. A Ge segregation layer at the SiGe/Si interface will be formed. When the sample was annealed above the melting point of Ge (1000 degrees C), the bottom Si-buffer layer could easily diffuse into the low temperature Ge layer (LT-Ge), also forming a Ge rich layer at the SiGe/Si interface. The results obtained from this investigation provide us important information about the stability of SiGe virtual substrate with a LT-Ge interlayer. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.