Dislocation Conversion in 4H-SiC Crystals Grown by Metastable Solvent Epitaxy

摘要

Dislocation conversion in 4H-SiC single crystals grown by metastable solvent epitaxy (MSE). was investigated using synchrotron X-ray topography, repeated polishing and molten KOH etching, and transmission electron microscopy (TEM). The conversion of basal plane dislocations to threading edge dislocations occurred not only near the interface between the MSE layer and the substrate, but also throughout the MSE layer. At the initial stage of MSE growth, all threading screw dislocations (TSDs) were converted into Frank-type basal plane stacking faults (Frank SFs). High resolution TEM observation revealed that the four extra SiC planes generated by this conversion were inserted among adjacent basal planes. These results suggest that the driving force for the conversion of TSDs is significantly larger for MSE growth than for growth by conventional chemical vapor deposition. A g-b analysis of the Frank partial dislocations (PDs) associated with the Frank SFs revealed that the total sum of the Burgers vectors of the four Frank PDs had two different values of b = c and b = c + a, and that approximately 50% of TSDs in the substrate had a Burgers vector component parallel to the a-axis.