Polytype Transformation by Replication of Stacking Faults Formed by Two-Dimensional Nucleation on Spiral Steps during SiC Solution Growth

Abstract

Polytype transformations on the 4H-SiC(0001) Si face during top-seeded solution growth have been investigated by transmission electron microscopy and micro-Raman spectroscopy. 4H-, 15R-, and 6H-SiC were grown on the 4H-SiC(0001) Si face via spiral growth. Once a polytype transformation from 4H-SiC to 15R- or 6H-SiC occurs, the polytype rarely returns to 4H-SiC. Just before the polytype transformation, a disturbance in the stacking sequence involving the introduction of stacking faults was observed. A polytype transformation during spiral growth can be understood in terms of the replication of stacking faults due to two-dimensional nucleation of a single bilayer on the spiral steps. This polytype transformation model shows good agreement with observed polytype transformation pathways as well as the disturbance in the stacking sequence at the interface between 4H-SiC and 15R-SiC.