Spectroscopic parameters of the absorption bands related to the local vibrational modes of carbon and oxygen impurities in silicon enriched with 28Si, 29Si,and 30Si isotopes

The IR spectra of all three Si isotopes in the form of bulk single crystals (²⁸Si with an enrichment of more than 99.9%, and ²⁹Si and ³⁰Si with an enrichment of more than 90%) have been studied at T = 300, 17, and 5 K in the spectral range 550–1200 cm^?1. The IR active local vibrational modes (LVM) of Si-¹²C centered at 605 cm^?1 and Si-¹⁶O-Si quasi-molecules in the region of 1136 cm^?1 for all the Si isotopes, in comparison with Si possessing a natural isotopic composition, as well as their isotopic shift at 300 and 17 K, have been determined. The dependence of the shape of the antisymmetric stretching vibration band for ²⁸Si-¹⁶O-²⁸Si in the spectrum of ²⁸Si on spectral resolution has been studied. The possibility of generalizing the IR spectroscopy method for the determination of carbon and oxygen impurities in Si possessing a natural isotopic composition to monoisotopic Si have been discussed.