Effects of polarized organosilane self-assembled monolayers on organic single-crystal field-effect transistors

The surface conductivity is measured by a four-probe technique for pentacene and rubrene single crystals laminated on polarized and nearly unpolarized molecular monolayers with application of perpendicular electric fields. The polarization of the self-assembled monolayers (SAMs) shifts the threshold gate voltage, while maintaining a very low subthreshold swing of the single-crystal devices (0.11 V/decade). The results, excluding influences of parasitic contacts and grain boundaries, demonstrate SAM-induced nanoscale charge injection up to similar to10(12) cm(-2) at the surface of the organic single crystals. (C) 2004 American Institute of Physics.