Equilibrium crystal shapes for 6H AND 4H SiC grown on non-planar substrates

Abstract

Growth of 6H and 4H SiC has been performed on Si-face substrates with etched stripe mesas under low supersaturation conditions (which is obtained by keeping the C:Si ratio in the gas phase low) at the two different growth temperatures of 1480 and 1620°C. The growth around the mesas was investigated by scanning electron microscopy and the facets which appear around the mesas could be identified as low index lattice planes. The difference in growth rate between these lattice planes was found to be less than ±25%. Modified polar Wulff plots are used to illustrate the growth rate in the different lattice directions, and could also be used to predict the growth habit for different geometries. As expected, the average growth rate is larger on the {11 2 n} than on the {1 1 0n} planes, but slow and fast growing planes exist for both sets of planes. Generally the growth rate is larger for planes with high n, and for the {1 1 0n} planes it is found that a slow growth rate could be correlated with a larger percentage of C ad-atoms to the plane. At the lower growth temperature a larger difference in growth rate between the fast and slow growing planes could be observed, probably due to a larger influence of the surface energies under these conditions.