Refractive index spectral dependence, Raman spectra, and transmission spectra of high-purity Si28, Si29, Si30, and Sinat single crystals
We performed precise measurement of the refractive index of stable silicon isotopes Si28, Si29, and Si30 single crystals with enrichments above 99.9at.% and a silicon single-crystal Sinat of natural isotopic composition with the Fourier-transform interference refractometry method from 1.06 to more than 80 μm with 0.1cm-1 resolution and accuracy of 2×10-51×10-4. The oxygen and carbon concentrations in all crystals are within 5×1015cm-3, and the content of the metal impurities is 10-5 10-6 at. %. The peculiar changes of the refractive index in the phonon absorption region of all silicon single crystals are shown. The coefficients of the generalized Cauchy dispersion function approximating the experimental refractive index values all over the measuring range are given. The transmission and Raman spectra are also studied.