The effect of surface finish on the dislocation density in sublimation grown SiC layers

The effect of the seed surface finish on the dislocation density of sublimation grown silicon carbide was investigated. Growth on seeds that were polished down to 1 μm diamond paste resulted in the nucleation of threading screw dislocations in a density of 10⁶ cm^-2 and threading edge dislocations in densities of 10⁷ cm^-2. Following the mechanical polish of the seeds with a hydrogen etch or chemo-mechanical polish prior to growth resulted in the screw dislocation density decreasing by four orders of magnitude and the threading edge dislocation density dropping two orders of magnitude. Using the dislocations density and the hydrogen etch rate, the depth of damage in mechanically damaged seeds was determined to be between 400 and 1000 Å.