Thermodynamic evaluation of the C-Cr-Si, C-Ti-Si, and C-Fe-Si systems for rapid solution growth of SiC

Solution growth of SiC is currently regarded as a promising process to produce high-quality SiC crystals. To date, Si-Cr, Si-Ti, and Fe-Si solvents have been used for rapid solution growth of SiC. However, optimization of the solvent system and composition is still needed to maximize the growth rate of high-quality SiC crystals. In this paper, to clarify the features of respective solvents from the viewpoint of the solubility of carbon, the C-Cr-Si, C-Ti-Si, and C-Fe-Si systems were evaluated by thermodynamic analysis. Phase relations in the respective ternary systems were investigated by the calculation of phase diagrams method. In addition, the solubility of carbon in Si-Cr, Si-Ti, and Fe-Si alloys at saturation with SiC was measured and its consistency with the estimated results was examined. Correlation of the experimental growth rate of SiC using Si-Cr, Si-Ti, and Fe-Si solvents was analyzed in terms of the supersaturation of carbon in each solution evaluated from the estimated temperature dependence of carbon solubility. Rate determining step for solution growth was presumed to be mass transfer in the liquid phase.