Effects of annealing on electronic and structural characteristics of pentacene thin-film transistors on polyimide gate dielectrics

We have systematically investigated the effects of annealing on the structures and electronic performances of pentacene field-effect transistors on polyimide gate dielectric layers. The mobility of these transistors increases from 0.07 to 0.12 cm(2)/V s by annealing at 140 degrees C. The density of charge traps can be reduced by annealing, thereby resulting in the improvement of the transistor characteristics. The x-ray diffraction measurements indicate that the crystal structure of pentacene on polyimide does not change after annealing up to 140 degrees C, while the crystal structure of pentacene on Si/SiO2 exhibits transitions from the (001) thin film phase to the bulk phase.