Ionized impurity scattering in n-doped C60 thin films

Carrier transport in organic films is usually dominated by hopping process, leading to different temperature dependence from that of inorganic crystals. The aurhors demonstrate that n-doped C-60 films show temperature dependence analogous to inorganic semiconductors. At low temperatures, the conductivity increases with temperature, around room temperature, a maximum is reached and then the conductivity decreases. These observations are confirmed by the dependence of mobility on doping level. In contrast to previous reports for organic thin films, the C-60 films show a decrease of mobility with increasing doping levels, i.e., they follow the well-known Matthiessen rule which is generally observed in inorganic semiconductors.