A proposal for CVD growth of 15R-SiC by observing the etch pits on 15R-SiC [formula omitted] C-face

Abstract

As grown Acheson crystals of 15R-SiC and 6H-SiC were etched by molten KOH. Etch pits peculiar to each polytype were observed both on C-face and Si-face of etched crystals. The inside of etch pit on the C-face was flat. Etch pits on 6H-SiC showed six-fold symmetry, and etching rate toward six equivalent 〈1 1 2 ̄ 0〉 was the fastest. In case of 15R-SiC, etching rate toward [1 1 ̄ 0 0] was faster than that of [ 1 ̄ 1 0 0] , and etch pits showed three-fold symmetry. Etching rate anisotropy between [1 1 ̄ 0 0] and [ 1 ̄ 1 0 0] of 15R-SiC was explained by the number of dangling bonds per edge atom. Though the chemical vapor deposition (CVD) growth of 15R-SiC has been conducted on Si-face 8.0° off-oriented toward 〈1 1 2 ̄ 0〉 , [1 1 2 ̄ 0] and [ 11 2 0] might not be equivalent in 15R-SiC. If the crystal grew at near-equilibrium condition, the difference between off-orientation toward [1 1 2 ̄ 0] and [ 11 2 0] might become obvious. Further research is necessary for the CVD growth of 15R-SiC to achieve high quality crystals.