Organic Field-Effect Transistors with Gate Dielectric Films of Poly-p-Xylylene Derivatives Prepared by Chemical Vapor Deposition

We have fabricated organic field-effect transistors (OFETs) using various dielectric films of poly-p-xylylene derivatives to investigate the correlation of field-effect mobility and the surface properties of the dielectric films under constant conditions of fabrication process and molecular backbone. The OFET using pentacene as the semiconductor and poly-chloro-p-xylylene as the dielectric film showed good performance for an OFET using a polymer dielectric film; the field-effect mobility was 0.81 cm²/Vs and the on/off current ratio was 1.4 × 10⁶. We observed an obvious tendency for the hydrophobic dielectric layers to give a higher field-effect mobility for both crystalline organic semiconductors and amorphous polymer semiconductor, though a significant correlation of field-effect mobility with the dielectric constant and surface roughness of the dielectric films was not observed.