Thermomigration of molten Cr-Si-C alloy in 4H-SiC at 1873-2273 K

Thermomigration of molten Cr-Si-C alloys in silicon carbide (SiC) along a quasi-binary Cr-SiC system at 1873-2273 K was evaluated by the temperature gradient zone melting method. Solute diffusivity in the molten alloy and distribution of Cr between 4H-SiC and the alloy were studied, where both properties are important for designing a process for the solution growth of single crystalline 4H-SiC. The migration was found to be controlled by interdiffusion in the molten alloy from the measured migration rate. The obtained interdiffusion coefficients were (0.11-1.3) x10(-7)m(2) s(-1), and these increased with increasing temperature. The Cr impurities in 4H-SiC were found to be distributed to maintain the thermodynamic equilibration with the alloy, and increased with temperature in the range of (0.26-2.2) x10(17) cm(-3). The thermodynamic property of Cr in SiC was assessed, and will enable the solubility of Cr in 4H-SiC grown at various solvent temperatures and compositions to be estimated.