2-DIMENSIONAL ELECTRICAL TRANSPORT OF PENTACENE THIN-FILMS DOPED WITH IODINE

The logarithmic electrical resistivities of pentacene (PEN) thin films doped with iodine in the direction parallel to the substrate plane fit the T-1/3 dependence well. This indicates that the lateral transport of the film was governed by two-dimensional variable range hopping. In contrast, the logarithmic resistivities of the films perpendicular to the substrate were observed to be almost independent of temperature and to be weakly T-1/2 dependent. This shows that the tunneling mechanism is predominant in perpendicular transport. Two-dimensional conduction of the film was confirmed by these transport properties, which was expected from the intercalated structure of PEN film doped with iodine.