Characterization of functionalized pentacene field-effect transistors and its logic gate application

Functionalized pentacene, 6,13-bis(tri-isopropylsilylethynyl)pentacene (TIPS-pentacene), field-effect transistors (FETs) were made by both thermal evaporation and solution deposition methods, and the mobility was measured as a function of temperature and intensity of incident illumination. The field-effect mobility (mu(FET)) has a gate-voltage dependent activation energy. A nonmonotonic temperature dependence was observed at high gate voltage (V-G <-30 V) with an activation energy of E-a similar to 60-170 meV, depending on the fabrication procedure. The gate-voltage dependent mobility and nonmonotonic temperature dependence indicate that shallow traps play important role in the transport of TIPS-pentacene films. The current in the saturation regime as well as the mobility increase upon light illumination in proportion to the light intensity, mainly due to the photoconductive response. Transistors with submicron channel length showed unsaturating current-voltage characteristics due to the short channel effect. Realization of simple circuits such as NOT (inverter), NOR, and NAND logic gates are demonstrated for thin film TIPS-pentacene transistors. (c) 2006 American Institute of Physics.