Electrical conductivity of alternate layer deposition of pentancene and tetracene superlattices

Superlattice thin films of pentacene (PEN) and tetracene (TET) were fabricated by alternate layer deposition using the sublimation method. The film showed a highly crystalline structure that was due to the strong aggregation tendency of polyacene compounds to form a layered monomolecular column structure. The crystalline structure of the films was drastically changed by doping with iodine. The doped films showed a highly ordered structure where an iodine monomelecular layer was intercalated between molecular columns of acene compounds in both PEN and TET. The doped films exhibited a large lateral conductivity of 10 Ω−1 cm−1 and attained giant anisotropy above 1012. This indicated that molecular columns of TET remained insulating upon doping to form a perfect two-dimensional conductor in the superlattice thin films.