Virtual substrates with relaxed SiGe buffers on Si substrates are needed for strain adjusted heterodevices with high cc content. We have investigated the degree of relaxation in thin (<0.1 mu m) SiGe layers grown by solid source molecular beam epitaxy (MBE) using a special low temperature growth step. Full relaxation (100%) of layers with a low temperature growth stage was achieved. X-Ray data suggest that SiGe buffers grown using this method are fully relaxed (100%), when appropriate values of Ge content, thickness and growth temperature are chosen. A typical sample with 28% Ge at total thickness of 70 nm and low temperature growth stage with 200 degrees C heater temperature is shown. TEM data indicate that the misfit dislocations are confined within the virtual substrate. Furthermore, the surface is smooth and free from strain-induced undulations and crosshatch.