Structure-performance relationship in pentacene-based thin-film transistors

Pentacene-based thin-film transistors were fabricated on Si:n+/alumina substrates with gold top-contact source and drain electrodes. The growth mechanism of the pentacene layer was followed by atomic force microscopy (AFM). On some devices, the alumina surface was modified with fatty acid self-assembled monolayers (SAM) prior to pentacene deposition. The first stage of the deposition was found two-dimensional on bare alumina and three-dimensional on the SAM treated substrates. This has important implications on the depth dependent mobility, as evidenced from a modeling of the current-voltage characteristics. It is found that SAM treated samples present higher performance with thick film, while the reverse is true for thin film.