Insight into segregation sites for oxygen impurities at grain boundaries in silicon

Abstract

The three-dimensional distribution of oxygen atoms segregated at Σ9{114} grain boundaries (GBs) in Czochralski-grown silicon ingots is analyzed within a high spatial resolution of less than 0.5 nm by atom probe tomography combined with a focused ion beam (FIB) operated at −150 °C. The analysis reveals a segregation of oxygen atoms within a range of 2.5 nm across the GB plane, which is much narrower in comparison with the previous reports obtained using a conventional FIB. The oxygen concentration profile accurately reflects the distribution of the segregation sites, which exist at bond-centered sites under tensile stresses above 2 GPa, as calculated by ab initio local stress calculations.

Segregation mechanism of arsenic dopants at grain boundaries in silicon

“…3). This result shows that the compositional modification at the GBs due to FIB irradiation can be suppressed by using LT-FIB technique, as reported [49,64,65]. Therefore, the concentration profile obtained by LT-FIB would significantly reflect the distribution of segregation sites, even though the impact of local magnification effects, about 0.5 nm in the segregation thickness [65], still remains.…”

“…Figure 3(a) shows that the 1D profile of As concentration peaks slightly off the GB plane, similar to the 1D profile of oxygen concentration [65]. Comparing the 1D profile with the atomic arrangement in the GB revealed by HAADF-STEM (shown in Fig.…”

Multicrystalline Informatics Applied to Multicrystalline Silicon for Unraveling the Microscopic Root Cause of Dislocation Generation

“…We also found that Σ3{113}/{557} GBs had a staircase‐like structure composed of nano‐facets of Σ3{111}/{111}‐like structure, similar to asymmetric Σ9{115}/{111} GBs, [ 55,56 ] in which the nano‐facet junctions were parallel to <1‐10>. Ab initio calculations revealed tensile bond strains of more than 2% along the nano‐facet junctions (Figure 6d), presumably due to long <110> reconstructed bonds, [ 57 ] and it would also act as dislocation sources. Actually, a number of dislocations are frequently generated at asymmetric GBs.…”

Atomic configurations and energies of Mg symmetric tilt grain boundaries: ab initio local analysis

“…Then we analyze the stability and structural characteristics, dominated by electronic behaviors, via our ab initio local-energy and local-stress scheme [19][20][21][22][23] based on the Bader partitioning [24], in order to investigate the origin of stability/instability of each GB configuration in hcp Mg. As summarized in our review article [23], our scheme provides the distribution of local energy and local stress of each atom in a GB region as the response of valence electrons against local structural disorder, which was quite useful to understand the stability and property of GBs in Al [20,25], Fe [21,22,26,27] and Si [28,29]. This is the first application of our scheme to GBs in bivalent simple metals, of which the comparison with previous results in other materials is quite interesting.…”