Abstract:
Pentacene films grown on sol-gel silica dielectrics showed a significant enhancement in field effect mobility, threshold voltages, and subthreshold swings. This letter investigates the contributing factors for the enhanced device characteristics. The smoother and more hydrophobic film surfaces of sol-gel silica (rms roughness of ∼1.9Å and water contact angle of ∼75°) induced larger pentacene grains, yielding mobilities in excess of ∼1cm2/Vs at an operating voltage of −20V. Different sol-gel silica film thicknesses showed similar trends in improved performances, indicating that this phenomenon is clearly a semiconductor-dielectric interface phenomenon rather than a bulk dielectric effect.