Abstract
The melt-back process has a significant effect on the quality of solution-grown SiC crystals. However, the phenomena surrounding the SiC dissolution into the molten alloy during the melt-back process have not been clarified. In this study, the behavior of 4H-SiC dissolution into molten alloy was investigated by using high-temperature in situ observation and subsequent KOH etching, and the effects of different doping conditions and crystal polarity were studied. Local dissolutions with hexagonal pyramid-shape originating from threading screw dislocation (TSD) were observed on the C face of n-type SiC with light nitrogen doping. Our analysis of their behavior revealed that the process was governed by the spiral dissolution. In addition to the dissolution at TSD, local dissolutions at threading-edge dislocations were observed on the Si face of the same crystal. The shape of the local dissolution at the dislocation was significantly affected by the doping conditions and the polarity of the SiC crystal. This local dissolution may occur during the melt-back process, suggesting that it is important to promote the dissolution while maintaining a smooth interface through the selection of the seed crystal and by keeping the degree of interface undersaturation small.
Highlights
The selection of a seed crystal material and its orientation is important for the growth of high-quality single crystals
In the growth of bulk 4H-silicon carbide (SiC) single crystals by the solution growth method [3–11], which is a potential technique for growing high-quality crystals, the damaged layer is removed by dissolving it through a melt-back process
The dissolution behavior of 4H-SiC {0001} into molten alloy was studied through in situ studies at ~1500 K, and the contribution of dislocations was clarified through the subsequent KOH etching
Summary
1. Introduction The selection of a seed crystal material and its orientation is important for the growth of high-quality single crystals. In the growth of bulk 4H-SiC single crystals by the solution growth method [3–11], which is a potential technique for growing high-quality crystals, the damaged layer is removed by dissolving it through a melt-back process. Without the melt-back process, adhesions of the alloy derived from vapors are present on the surface of the 4H-SiC seed crystal before seed touching the growth solution, which contributes to the formation of various defects, including the solvent inclusions [12].
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