Films of C60, at different stages of annealing of Tt=200°and 300°C have been electrically characterized over the temperature domain from -130°C to Tt. X-ray diffraction revealed a random polycrystalline fee structure with stacking defects of an intrinsic nature, due to deposition conditions. The value of room-temperature conductivity was found to be in the range (6.3-1.0) *10−10(0cm)−1. In the stable annealed state the conductivity showed an activated temperature dependence above 423 K and a non-activated dependence below 330-280 K. The activation energies Ea= 0.8 eV (film thickness 0.70 μm) and Ea= 1.0 eV (film thickness 2.40 μm) were in good agreement with the energy gap values (1.63 eV and 2.08 eV) which were deduced from the absorption spectral dependence. Annealing decreased the non-activated contribution to conduction, extending the intrinsic conduction temperature range.
展开▼
