Segregation mechanism of arsenic dopants at grain boundaries in silicon
Segregation mechanism of arsenic dopants at grain boundaries in silicon
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DOI：
10.1080/27660400.2021.1969701
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发表时间：
2021-01
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影响因子：
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通讯作者：
Y. Ohno;T. Yokoi;Y. Shimizu;J. Ren;K. Inoue;Y. Nagai;K. Kutsukake;K. Fujiwara;A. Nakamura;K. Matsunaga;H. Yoshida
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作者：
Y. Ohno;T. Yokoi;Y. Shimizu;J. Ren;K. Inoue;Y. Nagai;K. Kutsukake;K. Fujiwara;A. Nakamura;K. Matsunaga;H. Yoshida
采用原子探针层析成像（APT）结合低温聚焦离子束（LT-FIB）、扫描透射电镜（SEM）和从头计算等相关分析方法，研究了硅中As掺杂在晶界（GBs）的三维分布。113 {111} GBs，仅由具有小的键扭曲的6元环组成，不表现出明显的As偏析。同时，据推测，As原子将通过自发引入的各向异性键畸变，以降低施主能级，如Jahn-Teller畸变，在其他GB中的5元环处分离。此外，APT与LT-FIB相结合表明，在倾斜角大于70.5°的倾斜GBs中，不可避免地引入了在109 {114}和109 {111}/{115} GBs中重建的拉伸键周围的优先As偏析。据推测，作为原子将形成作为二聚体在拉伸键和相邻的债券，由于与五价电子的趋势，形成一个三配位的配置，这是有效地实现了作为二聚体的长度长。这项工作提供了重要的见解作为隔离在GB的，它主要是由电子相互作用取决于作为原子的价电子的特性，以及在GB的本地键扭曲，通过各向异性键扭曲和二聚。图形摘要
ABSTRACT Three-dimensional distribution of arsenic (As) dopants at Σ3{111}, Σ9{221}, Σ9{114}, and Σ9{111}/{115} grain boundaries (GBs) in silicon (Si) is examined by correlative analytical methods using atom probe tomography (APT) combined with low-temperature focused ion beam (LT-FIB), scanning transmission electron microscopy, and ab initio calculations. Σ3{111} GBs, consisting of only 6-membered rings with small bond distortions, do not exhibit an apparent As segregation. Meanwhile, it is hypothesized that As atoms would segregate at 5-membered rings in the other GBs via anisotropic bond distortions spontaneously introduced so as to lower the donor level, as Jahn-Teller distortions. In addition, APT combined with LT-FIB suggests preferential As segregation around stretched bonds reconstructed in Σ9{114} and Σ9{111}/{115} GBs, that are inevitably introduced in the tilt GBs with the tilt angle larger than 70.5°. It is hypothesized that As atoms would form As dimers at stretched bonds and the adjacent bonds, due to the tendency of As with five valence electrons to form a three-coordinated configuration, which is efficiently attained by an As dimer of a long length. This work provides important insights into As segregation at GBs; it is mainly determined by electronic interactions depending on the characteristics of valence electrons of As atoms, as well as on local bond distortions at GBs, via anisotropic bond distortions and dimerization. GRAPHICAL ABSTRACT