Fabrication of high-mobility organic single-crystal field-effect transistors with amorphous fluoropolymer gate insulators

High-mobility rubrene single-crystal field-effect transistors are built on highly water- and oil-repellent fluoropolymer gate insulators. Roughness is introduced at the surface once to provide good adhesion to metal films and photoresist polymers for stable electrodes. Before constructing interfaces to crystals, smoothness of the fluoropolymer surface is recovered by annealing at a moderate temperature to maximize carrier mobility. Mobility values estimated in the saturation region reproducibly exceeded 15 cm2/V s for all the 10 devices, reaching 30 cm2/V s for the best two devices. The results demonstrate that the water-repellency and smoothness of the dielectric polymers are favorable for the excellent transistor performance.