Solvent Design for High-Purity SiC Solution Growth

Abstract

In order to design a solvent for high-purity SiC solution growth, the impurity incorporation and the carbon solubility of various solvent materials have been investigated. Among the transition metal elements, the impurity elements of Cr, Ti, V and Hf are more readily incorporate during the solution growth than the other transition metal elements. The thermodynamic calculation revealed that the Y-Si solvent has relatively large carbon solubility, which is comparable to the Cr-Si and Ti-Si solvents often used in the solution growth of bulk SiC crystals. From these results, the Y-Si solvent is expected to be a suitable solvent for the high-purity SiC solution growth. Furthermore, we have demonstrated that the Y-Si solvent can achieve lower incorporation of metal impurity in the grown crystal than the Cr-Si solvent maintaining the growth rate.

Review of solution growth techniques for 4H-SiC single crystal

“…The addition of transition group metals, such as Ti [8, 14-16, 19, 40-52] , Cr [29,30,43,50, , Co [63,76] , Fe [77][78][79][80] , etc. or rare earth metals, such as Ce [81] , Y [82] , Sc, etc. to the Si melt allows the carbon solubility to exceed 50at.% in a state close to thermodynamic equilibrium.…”

“…The C solubility rose as the Cr content increased, reaching 3.9mol.% at x Cr =40mol.%. Harada et al [82] investigated the carbon solubility of the X-Si (X=Cr, Ti, Fe, Zr, Co, Mo, W, Y and Ni) solvents. Among those elements, doping Y and Zr showed higher improvement of C solubility compared to Si-Cr systems.…”

Influence of interfacial energy on the growth of SiC single crystals from high temperature solutions

“…Optimizing the solution composition is hence of importance to the stable crystal growth of high quality SiC single crystals via TSSG. So far, there have been a lot of studies devoted to the exploration of solution systems, [11][12][13][14][15][16][17][18] typically including C-Si-Fe, 19 C-Si-Ti, [20][21][22] C-Si-Cr, [23][24][25] C-Si-Cr-Al, 26 C-Si-Cr-Ce-Al, 27 and C-Si-Cr-Co (ref. 28), to grow SiC at suitable temperatures and growth rates.…”