[20a-C202-1~11] 15.7 Crystal characterization, impurities and crystal defects

[20a-C202-9] Insight into dislocation generation at Σ3 grain boundaries in cast-grown silicon ingots

〇Yutaka Ohno¹, Hideto Yoshida², Tatsuya Yokoi³, Katsuyuki Matsunaga³, Koji Inoue¹, Yasuyoshi Nagai¹, Noritaka Usami³ (1.IMR, Tohoku Univ., 2.SANKEN, Osaka Univ., 3.GSE, Nagoya Univ.)

Keywords:high-performance multicrystalline silicon, dislocations, Sigma-3 grain boundary

The sigma-3 grain boundaries (GBs) acting as dislocation sources in high-performance multicrystalline silicon ingots have a stepped structure composed of the symmetric sigma-3 GB segments lying on {111} and {112}. Dislocations are preferentially generated at the stepped edges, and the Burgers vectors of the dislocations are parallel to the stepped edges. Theoretical analyses based on the structural data suggest a high shear stress concentrated at the stepped edges, as well as large tensile strains at the stepped edges, by which the critical stress needed for dislocation generation would be reduced. The concentration of shear stress at tensile-strained step edges would result in the generation of high density dislocations.