Optical and structural properties of fullerene films doped with cadmium telluride

Composite thin-film structures based on C$_{60}$/CdTe were prepared by discrete vacuum evaporation in a quasi-closed volume and by vacuum evaporation from a Knudsen cell. The synthesized fullerene samples contained cadmium telluride with a content ranging from 1 to 50 wt%. The morphology and composition of the films were controlled using scanning electron microscopy and energy-dispersive X-ray analysis. The optimum geometry, the total energy, and the spectrum of excited states of the fullerene-cadmium telluride molecular complex were calculated by quantum-chemical methods. The spectral dependences of the photo-luminescence, Raman scattering, extinction coefficient, and refractive index were measured for different compositions. It was found that, in contrast to the spectra of pure fullerene, the luminescence and absorption spectra of the fullerene doped with cadmium telluride exhibit an additional peak in the wavelength range of 600–620 nm. These data were interpreted as the existence of dipole-allowed transitions in the spectrum of excited singlet states of the fullerene due to the interaction with cadmium telluride. The composite films had an increased resistance to degradation under the action of oxygen and water vapor.