Optical and electrical properties of C60Tex films

The structure, composition, and electrical and optical properties of thin t ellurium-intercalated fullerene films C60Tex are investigated. The samples of compositions from C60Te0.1 to C60Te6 are prepared by thermal evaporation . The sample composition and the impurity distribution are controlled by th e Rutherford backscattering technique. The Raman vibrational spectra indica te changes in the symmetry of a C-60 molecule: the strain of the molecule i ncreases with a decrease in the tellurium concentration and decreases as th e tellurium impurity concentration increases. The evolution of the optical absorption spectra and the electrical conductivity suggests that intercalat ion of a tellurium impurity leads to modification of the electronic structu re of the material. This process is accompanied by a shift and change in sh ape of the optical absorption edge and a change in the electrical conductiv ity of films by several orders of magnitude depending on the composition. T he electrical conductivity is minimum at a low tellurium impurity content. (C) 2001 MAIK "Nauka/Interperiodica".