Effects of surface chemical composition on the early growth stages of alpha-sexithienyl films on silicon oxide substrates

Year: 2006

Authors: Dinelli F., Moulin J.F., Loi M.A., Da Como E., Massi M., Murgia M., Muccini M., Biscarini F., Wie J., Kingshott P.

Autors Affiliation: CNR – Istituto per lo Studio di Materiali Nanostrutturati, Bologna Division, Via P. Gobetti 101, 1-40129 Bologna, Italy; Danish Polymer Centre, Risoe National Laboratory, Denmark

Abstract: In organic field effect transistors, charge transport is confined to a narrow region next to the organic/dielectric interface. It is thus extremely important to determine the morphology and the molecular arrangement of the organic films at their early growth stages. On a substrate of technological interest, such as thermally grown silicon oxide, it has been recently found that alpha-sexithienyl aggregates made of flat-lying molecules can simultaneously nucleate besides islands made of molecules standing vertical. In this paper, we investigate the effects due to variations in surface chemical composition on alpha-sexithienyl ultrathin film formation. Flat-lying molecules are no longer detected when Si-OH groups present at the surface are chemically removed but also when the Si-OH or Si-H group density is maximized. This gives evidence that variations in the surface chemical composition can largely affect the nucleation and growth processes of organic/dielectric interfaces. We hypothesize that isolated OH groups can interact with alpha-sexithienyl molecules and anchor them down flat with respect to the surface.

Journal/Review: JOURNAL OF PHYSICAL CHEMISTRY B

Volume: 110 (1)      Pages from: 258  to: 263

KeyWords: FIELD-EFFECT TRANSISTORS; THIN-FILMS; ORGANIC TRANSISTORS; MASS-SPECTROMETRY; SEXITHIOPHENE
DOI: 10.1021/jp053814g

Citations: 36
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