Influence of stacking faults on the growth of polytype structures

Abstract

The faulted matrix model of polytypism suggested in the preceding paper has been applied to the deduction of SiC polytypes. It is shown that all the SiC polytypes so far regarded as ‘anomalous’ can result from an appropriate screw dislocation ledge exposed in a 6H, 15R or 4H matrix. The probable fault configurations in each of these parent structures have been determined from a calculation of stacking fault energy. The most frequently occurring structure series in SiC are those which have the lowest stacking fault energy. Thus, there is an excellent agreement between the polytype structures expected on the basis of the faulted matrix model and those actually observed. The limitation of the Zhdanov numbers to 2, 3 and 4 in a polytype structure is explained. It is possible to predict the more probable structures for a polytype on the basis of the above model.