ABSTRACT
The results of the precise measurement of the refractive index of stable germanium isotopes Ge72, Ge73, Ge74, and Ge76 single crystals with high enrichment and a germanium single-crystal Genat of natural isotopic composition with the Fourier-transform interference refractometry method from 1.94 to 20 µm with 0.1 cm-1 resolution and accuracy of 2×10-5 to 1×10-4 are shown. The content of 72 impurities measured by the mass spectrometric method was below 10-5-10-6 wt. %. Oxygen and carbon concentrations measured by IR spectroscopy in all crystals are within 5×1015 cm-3. All germanium crystals have a hole conductivity with specific electric resistivity of 45-50 Ohm×cm. 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 given.
ABSTRACT
This corrects the article DOI: 10.1038/srep44813.
ABSTRACT
The low dielectric losses of an isotopically pure single crystal 28Si sample were determined at a temperature of 20 mK and at powers equivalent to that of a single photon. Whispering Gallery Mode (WGM) analysis revealed large Quality Factors of order 2 × 106 (dielectric loss ~5 × 10-7) at high powers, degrading to 7 × 105 (dielectric loss ~1.4 × 10-6 at single photon energy. A very low-loss narrow line width paramagnetic spin flip transition was detected with extreme sensitivity in 28Si, with very small concentration below 1010 cm-3 (less than 10 parts per trillion) and g-factor of 1.995 ± 0.008. Such determination was only possible due to the low dielectric photonic losses combined with the long lifetime of the spin transition (low magnetic loss), which enhances the magnetic AC susceptibility. Such low photonic loss at single photon energy combined with the narrow line width of the spin ensemble, indicate that single crystal 28Si could be an important crystal for future cavity QED experiments.
ABSTRACT
We performed precise measurement of the refractive index of stable silicon isotopes 28Si, 29Si, and 30Si single crystals with enrichments above 99.9 at.% and a silicon single-crystal natSi of natural isotopic composition with the Fourier-transform interference refractometry method from 1.06 to more than 80 µm with 0.1 cm(-1) resolution and accuracy of 2×10(-5) 1×10(-4). The oxygen and carbon concentrations in all crystals are within 5×10(15) cm(-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.
