Effects of Hydrogen on the Microstructure and Stability of a Structural SiC

Annealing a structural SiC in a hydrogen atmosphere causes the partial amorphization of the SiC structure primarily at the surface, in the voids, and in the grain boundaries that are closely associated with either of these two gas-solid interfaces. Analysis of the material hydrogenated at 1,400{degree}C in a 40:60 H{sub 2}:Ar atmosphere shows that the amorphous SiC, a-SiC:H, is seemingly more stable than is the crystalline SiC, c-SiC. A model for this hydrogenation process, which is based on bond strength considerations and suggests that amorphization is limited by stresses caused by the volume change inherent in the transformation of the higher density c-SiC to the lower density a-SiC:H, is given.