Estimation of C Solubility at SiC Saturation from the Reaction of Carbon Crucible with Si-Cr Solvent for Top-Seeded Solution Growth

The reaction between a carbon crucible and Si-Cr solvent, and the carbon solubility at SiC saturation in Si-Cr solvent were investigated using infrared absorption after combustion, field-emission scanning electron microscopy, and electron probe microanalysis. Si0.6Cr0.4, commonly used for silicon carbide crystal growth, was maintained in a carbon crucible at 1500-1950 degrees C for several minutes. The amount of carbon dissolved in the solvent was determined. The carbon content initially increased for 5 min, then remained constant until 10th min, and finally increased again with time at high temperature. According to microanalysis, the second increase in carbon content was due to the crystallization of small SiC grains in the solvent after reaching saturation, while the constant carbon content was due to the equilibrium between the SiC interlayer along the crucible wall and the solvent. Assuming the plateau of carbon content closely represented the carbon solubility at each temperature, a pseudo binary phase diagram was created for Si and C. Experimentally obtained constant carbon contents is in good agreement with the carbon solubilities calculated using CALPHAD.