[en] We describe a new technique for the fabrication of a thin strain relaxed buffer (TSRB). This method is based on the incorporation of carbon during the epitaxial growth of a thin constant composition Si_0.78Ge_0.22 layer. An annealing step is carried out after growth in order to increase the relaxation and therefore the stability of the buffer. This method allows to prepare smooth and defect free TSRBs with 91% relaxation. First Hall mobility measurements at 77 K of strained silicon on top of the TSRB (single side modulation doped structure) show promising electron mobility value of 18,500 cm²/(V s)