[19p-131-1~15] 15.7 Crystal characterization, impurities and crystal defects

[19p-131-7] Impact of the deviation of the tilt angle on the recombination activity and the impurity segregation ability of S3{111} symmetric tilt boundaries

〇Yutaka Ohno¹, Kentaro Kutsukake¹, Takehiro Tamaoka², Seiji Takeda², Yasuo Shimizu³, Naoki Ebisawa³, Koji Inoue³, Yasuyoshi Nagai³, Noritaka Usami⁴ (1.IMR, Tohoku Univ., 2.ISIR, Osaka Univ., 3.The Oarai Center, IMR, Tohoku Univ., 4.GSE, Nagoya Univ.)

Keywords:asymmetric grain boundaries, silicon solar cells

We discuss the recombination activity of asymmetric Σ3{111} GBs with the <110> tilt axis, whose GB planes are slightly inclined from {111}. Even though the activity is negligible for the symmetric Σ3{111} GBs of which the GB plane is just on {111}, the activity is high for the asymmetricΣ3{111} GBs even when their inclination angle is small. Most segments of the asymmetric GBs are composed of arrays of GB dislocations lying on symmetric Σ3{111} GBs. Those dislocations are edge-type with the Burgers vector of 1/3<111>. Atom probe tomography reveals that oxygen atoms would segregate at the atomic sites under tensile stress above about 2 GPa, which are introduced along the GB plane due to the GB dislocations. Carbon atoms also segregate, while they would locate only nearby the dislocation cores. The correlation between the recombination activity and the segregation ability of impurity atoms will be discussed.