Lattice distortion induced site dependent carbon gettering at twin boundaries in silicon

Abstract

The interactions between substitutional carbon atoms and Σ3 {111}, Σ9 {221}, and Σ27 {552} twin boundaries (TB) in silicon were investigated by first-principles calculations. The preferential segregation sites and segregation energy for carbon at different TBs were determined. It shows that segregation of carbon atoms at Σ3 {111} TB is energetically unfavorable while Σ9 {221} and Σ27 {552} TBs are efficient gettering centers for carbon. A linear relationship between the atomic-site specific segregation energy for carbon at TBs and the average bond length (ABL) of the atomic site is deduced.

Carbon segregation at Σ3 {1 1 2} grain boundaries in silicon

“…{112} GB. This behavior is analogous to the C segregation in Σ27 {552} TB in Si, as studied in a previous work [23], in which the joint site of five-fold and two six-fold rings was predicted to be the most attractive for C segregation. The utmost positive γ seg , i.e.…”

“…In a previous work [23], it was revealed that the intrinsic lattice distortion (mainly bond length deviation) in the TBs in mc-Si is the main driving force for the C gettering, where core sites with a smaller ABL in the TBs exhibit a higher propensity for C segregation. A linear correlation was demonstrated between the atomic-site specific segregation energy for C at TBs and the ABL of atomic sites [23]. An attempt is also made to correlate the segregation energy of C and the geometrical character of the segregation sites (including ABL, bond angle, etc.)…”

“…Less effort has been put on the gettering behavior of C solutes along GBs in mc-Si. In a previous work, we have investigated the C gettering behavior along twin boundaries (TBs) of Σ3, Σ9 and Σ27 in mc-Si [23]. It was found that a linear correlation between the C segregation energy at TBs and the average bond length (ABL) of the atomic sites exists.…”

Segregation mechanism of arsenic dopants at grain boundaries in silicon

“…Considering the detection limit of 0.01 at.% expected for GB segregation in our experiments [40], Γ As would increases superlinearly with increasing γ GB . The segregation characteristic for As dopants is, therefore, different from that for neutral impurity atoms such as oxygen [36,52] and carbon [53,54], in which the number of segregating atoms would exhibits a linear correlation with γ GB via elastic interactions [36] .…”

Phase diagram of grain boundary facet and line junctions in silicon

“…Furthermore, density-functional theory (DFT) calculations show the S-3 GB to favor interstitial Fe [11] as well as P and As substitutional [10] segregation. Both {112} boundaries also show very different site selectivity for C substitutionals [12].…”