Single Domain Transport Measurements Of C-60 Films

Thin films of potassium doped C-60, an organic semiconductor, have been grown on silicon. The films were grown in ultrahigh vacuum by thermal evaporation of C-60 onto oxide-terminated silicon as well as reconstructed Si(111). The substrate termination had a drastic influence on the C-60 growth mode which is directly reflected in the electrical properties of the films. Measured on the single domain length scale, these films revealed resistivities comparable to bulk single crystals. In situ electrical transport properties were correlated to the morphology of the film determined by scanning tunneling microscopy. The observed excess conductivity above the superconducting transition can be attributed to two-dimensional fluctuations.