Oriented growth of sexithiophene induced by edge of metal electrodes

Recently it has been shown that the "graphoepitaxy" of organic semiconductor α-sexithiophene (6T) occurs on artificial periodic grooves fabricated on thermally-oxidized Si substrates. In the present study, similarly oriented growth of 6T thin films was found around the edge of metal electrodes. Using this phenomenon to realize single crystalline organic transistors, substrates with short channel Au electrodes were fabricated by photolithography, and 6T films were grown on these substrates by molecular beam deposition. The {010} planes of 6T crystals tended to face the wall of the channel (electrode edge), probably due to the chemical affinity of Au for S atoms in 6T molecules. The transistor characteristics of the test device were measured, and the results suggested that this orientation control technique using the shape of electrodes would lead to improvements in device performance.