Thermal decomposition cavities in physical vapor transport grown SiC

The relationship between the formation of thermal decomposition cavities and seed mounting in physical vapor transport grown silicon carbide was investigated. Experimental results indicate that voids exist in the attachment layer between the single crystal seed and graphite crucible lid. These voids lead to the formation of cavities in the seed and grown boule by local decomposition of the seed, transport of silicon bearing species across the void and the deposition of silicon on, and diffusion into, the porous graphite lid. The application of a diffusion barrier on the seed crystal backside is shown to suppress the formation of thermal decomposition cavities.