Conductivity improvement of epitaxial-grown Mg-doped C60 thin films

The epitaxial growth of Mg-doped C₆₀ films has been investigated. It is found that the epitaxial growth of Mg-doped C₆₀ film is enabled by using mica (001) substrate in the low Mg concentration region (Mg/C₆₀ molar ratio < 1). The crystal quality of the epitaxial Mg-doped C₆₀ film is improved drastically in compared with micro-crystalline film on glass substrate. Such drastic improvement of crystal quality in the epitaxial films results significant increase in conductivity. This result may indicate the significant increase of carrier mobility. In addition, the relation between conductivity and Mg concentration suggests the possibility that two valence electrons per Mg atom contribute the electrical conduction.