Optical spectroscopy of thin C$_{60}$:CdS composite films

The fabrication procedure, structure, and optical spectroscopy data for thin composite films based on a fullerene material with a 0.5–10% cadmium-sulfide impurity content are reported. The technology for producing structures with a composition gradient in a single vacuum cycle is developed. The samples are studied by atomic-force microscopy, Raman spectroscopy, and photoluminescence measurements. At the optimal CdS content, charge transfer to fullerene molecules is observed. This effect is apparently responsible for the zero-barrier polymerization of the films. In the photoluminescence spectra of the composite films, a 0.09–0.11 eV shift of the peak to shorter wavelengths and an increase in the photoluminescence intensity in comparison to the photoluminescence peak position and intensity in pure fullerene samples are detected. The composite structures with a CdS-content gradient through their thickness exhibit rectifying current-voltage characteristics.