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

The three-dimensional distribution of oxygen atoms segregated at sigma 9{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 degrees 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.

Automated summary

Through the use of atom probe tomography combined with a focused ion beam operated at -150 degrees C, the three-dimensional distribution of oxygen atoms segregated at sigma 9{114} grain boundaries in Czochralski-grown silicon ingots was analyzed with high spatial resolution. The analysis revealed a narrow segregation range of oxygen atoms across the grain boundary plane, with segregation sites existing at bond-centered sites under tensile stresses above 2 GPa, as calculated by ab initio local stress calculations.