[15p-D511-1~11] 15.7 Crystal characterization, impurities and crystal defects

[15p-D511-9] Quality of silicon substrate and point defects (9) Non-uniformity of lattice parameter and carbon concentration in Avogadro crystal

〇Naohisa Inoue¹, Shuichi Kawamata¹, Shuichi Okuda¹ (1.Osaka Pref. Univ. Radiation Research Center)

Keywords:silicon crystal, lattice parameter, carbon

New International system of units relies on the ultra-precise measurement of lattice parameter (LP), volume and weight of ²⁸Si crystal. Nonuniformity of LP in specimen due to defects degrades the reliability. The measured LP nonuniformity was analyzed here. In the sample with C concentration ([C]) of 10¹⁵/cm³ at the bottom of the crystal, 1 dimensional map shows nearly constant LP with repeated sharp dips. Local [C] was estimated to be about 0.1 and 5 x [C]av. Nearly constant LP is equal to LP₀ of C-free crystal within the experimental error. Comparison with LP of the Avogadro sample gives its absolute value. It will be fruitful to improve the detection limit of SIMS profiling and analyze the result through segregation kinetics. The effect of point defects and grown-in defects on LP will be examined in the near future.