Prymak M. Effect of fabrication conditions and irradiation on the optical characteristics of composites with CdSe-type nanocrystals

Optical spectroscopic techniques were applied to study the effect of fabrication conditions and irradiation on the optical characteristics of composites with CdSe-type nanocrystals embedded in dielectric matrices. Ternary Cd1-xZnxSe nanocrystals were obtained by solid-state precipitation in a borosilicate glass matrix, their fundamental parameters were determined from Raman scattering and optical absorption spectra. Zinc content in the nanocrystals is shown to increase with the thermal treatment temperature and duration due to its diffusion from the matrix into the nanocrystals. Molecular selenium dimers Se2 are shown to be formed in cadmium- and selenium-doped borosilicate glass at the stage of high-temperature annealing, this being confirmed by the corresponding sharp bands near 325 and 650 cm-1 emerging in the Raman spectra. Meanwhile, the formation of tellurium molecular dimers Te2 and precipitation of elemental tellurium in Te-doped borosilicate glass is possible at lower temperatures when the heat treatment parameters are beyond the range optimal for the formation of tellurium-containing II-VI nanocrystals. Quaternary CdS1-x-ySexTey nanocrystals were obtained by solid-state precipitation in borosilicate glass and identified based on their Raman spectra. The chemical composition of these nanocrystals with three-mode behaviour can be evaluated based on the ratio of CdTe-like, CdSe-like, and CdS-like LO phonon band intensities in the Raman spectra with the account of corresponding electron-phonon interaction constants.