abstract A procedure for the optimization of a 3C–SiC buffer layer for the deposition of 3C–SiC/(001) Si is described. After a standard carbonization at 1125 1C, SiH4 and C3H8 were added to the gas phase while the temperature was raised from 1125 1C to the growth temperature of 1380 1C with a controlled temperature ramp to grow a thin SiC layer. The quality and the crystallinity of the buffer layer and the presence of voids at the SiC/Si interface are related to the gas flow and to the heating ramp rate. In order to improve the buffer quality the SiH4 and C3H8 flows were changed during the heating ramp. On the optimized buffer no voids were detected and a high-quality 1.5 μm3C–SiC was grown to demonstrate the effectiveness of the described buffer