[19p-Z29-1~13] 15.7 Crystal characterization, impurities and crystal defects

[19p-Z29-4] Mechanism for segregation of arsenic dopants at grain boundaries in silicon

〇Yutaka Ohno¹, Yasuo Shimizu^1,5, Jie Ren¹, Tatsuya Yokoi², Koji Inoue¹, Yasuyoshi Nagai¹, Hideto Yoshida³, Kentaro Kutsukake⁴, Kozo Fujiwara¹, Atsutomo Nakamura², Katsushi Matsunaga² (1.IMR, Tohoku Univ., 2.GSE, Nagoya Univ., 3.ISIR, Osaka Univ., 4.RIKEN, 5.NIMS)

Keywords:Silicon, Grain boundary segregation

Three-dimensional distribution of arsenic (As) atoms at grain boundaries in silicon s is examined by atom probe tomography (APT) combined with low-temperature focused ion beam (LT-FIB), STEM, and ab initio calculations. It is shown that As atoms would segregate at the lattice sites under tensile stresses via elastic interactions. Also, APT combined with LT-FIB suggests preferential As segregation at stretched <1-10> reconstructed bonds under high tensile stresses, that would be introduced in the <1-10> tilt GBs with the tilt angle larger than 70.5^o. It is hypothesized that As atoms would form As dimers at the reconstructed bonds via electronic interactions. The present work provides important insights on As segregation at GBs; it is determined not only by elastic interactions due to the intrinsic lattice distortions at GBs, but also by electronic interactions depending on the characteristics of valence electrons of As atoms as well as on local atomic configuration at GBs.