Papers by Keyword: Molten KOH Etching

Abstract: We investigated the effect of a melt-back process on the quality of the grown crystal in 4H-SiC solution growth. In our experiments, the crystal was grown by top-seeded solution growth (TSSG) method with and without melt-back, following which the quality of the obtained crystals was compared. When solution growth was carried out without melt-back, solvent inclusions and a different polytype were observed. When molten KOH etching was conducted, the dislocation density in the crystals at the early stage of growth became much higher than that in a seed crystal. Solvent inclusions, a different polytype, and an increase in dislocations were suppressed when solution growth was performed with melt-back. It was confirmed that melt-back is necessary to prevent the deterioration of crystal quality at the early stage of solution growth.

Abstract: The growth of 6H-SiC crystal from Si-Ti-C ternary solution was conducted under the temperature gradient and the crystalline quality evaluations of the grown crystals were carried out. 6H-SiC(0001) on-axis pvt-grown crystal was used as a seed crystal. Micropipes in the seed crystal were terminated during the solution growth and 28mm􀊷28mm self-standing micropipe-free SiC crystals were obtained. The quality of the grown crystals was investigated by SIMS, high-resolution x-ray diffraction and molten KOH etching. The content of residual impurities in the SiC were very low. The X-ray 􀐢-rocking curves of the solution grown SiC showed single peak with high peak intensity ,while that of the seed crystal showed several peaks due to the misoriented domains. Moreover, it was found that the number of etch-pit in the grown crystal is much less than that in the seed crystal and it decreases with the increase of the growth thickness. These results indicate that the crystalline quality of grown crystal was significantly improved during the solution growth.