[15p-A301-1~13] 15.6 IV族系化合物（SiC）

▼ [15p-A301-5] Analysis of the Effect of Solvent Composition on Suppression of Inclusion in SiC Solution Growth by Phase Field Method

〇HUIQIN ZHOU¹、Yuma Fukami¹、Hisaki Takemoto¹、Yifan Dang¹、Miho Tagawa^1,2、Shunta Harada^1,2、Toru Ujihara^1,2 (1.Grad. Sch. Eng. Nagoya Univ.、2.IMaSS, Nagoya Univ.)

キーワード：SiC, Top seed solution growth, Solution inclusion

The top-seeded solution growth (TSSG) method is a potential method for producing high-quality bulk SiC crystals since the macrosteps advancing on the crystal surface help convert threading dislocations into basal plane dislocations. Although high macrosteps are necessary for the threading dislocation conversion phenomenon, an over-developed macrostep is a cause of the solvent inclusions defect, because higher steps tend to meander, and elevating the step instability. The step instability can be affected by tiny changes in solvent composition. However, previous research has rarely focused on the effect of solvent composition on the suppression of inclusions. Among the several candidates of solvent compositions, Si-Cr binary solvent is widely accepted for SiC growth due to its high carbon (C) solubility. To clarify the effect of solvent composition on the suppression of inclusions formation and determine a suitable Cr concentration, a phase field model coupling with the C and Cr diffusion field is proposed in this study.
The simulation results show that as the step advances, a cellular structure with a deep groove is formed at first, in the case of insufficient diffusion of C, the cellular structure transforms to inclusion. Taking account of the effect of Cr concentration on C solubility, C and diffusivity, and solution viscosity, the step growth speed and cellular groove depth under different Cr concentrations were compared.As result, the Cr concentration should not exceed 50% to suppress the formation of inclusions while maintaining a fast growth rate. This model can also be used for the design of other solution components.