Homogeneity Characterization of Lattice Spacing of Silicon Single Crystals

The homogeneity of the lattice spacing of silicon single crystals was investigated by a self-referenced lattice comparator. Strain measurements were performed on single crystals from an 28Si ingot (Avo28), which was used to determine the Avogadro constant. A swirl pattern was observed for sample 9.R1 cut from the tail side of the Avo28 ingot. The lattice spacing distribution of seed-side sample 4.R1 was smooth and homogeneous. The lattice spacing distribution was larger for the sample with higher impurities of carbon and oxygen.