Voids were observed at SiC/Si interfaces below SiC layers which had been grown by means of chemical vapor deposition at high temperatures. It was shown that the volume of voids per unit area was proportional, to the O concentration in the Si substrate, over 7 orders of magnitude. Dynamic reflectivity measurements showed that the voids formed during the carbonization step; especially when C, which had diffused deeply into the Si substrate, diffused back towards the new SiC layer at the substrate surface. This back-diffusion was due to an inversion of the sign of the C concentration gradient. It was associated with the formation of CO, which resulted from the reduction of SiO or SiO2 that was dissolved in the Si substrate. It was suggested that C diffusion in Si could improve the removal of O.

A.Leycuras: Applied Physics Letters, 1997, 70[12], 1533-5