The factors influencing the graphoepitaxy of organic semiconductor α -sexithiophene (6T) on thermally oxidized silicon substrates were studied and it was discovered that a wider pitch in the microgrooves decreased the degree of graphoepitaxy. A more significant finding was that in-plane orientation could be changed by simple surface treatment. On UVozone-treated substrates (hydrophilic condition), the b -axis of 6T was parallel to the grooves. Further surface treatment with hexamethyl-disiloxane (under hydrophobic conditions) changed this in-plane orientation by 90°. This change is due to the interaction between the topmost chemical species (functional groups) of the groove walls and organic molecules, a behavior peculiar to organic graphoepitaxy and exploitable for optimal orientation control in device processing. The nucleation and growth processes that cause the graphoepitaxy are discussed, based on the experimental results.
ASJC Scopus subject areas
- Physics and Astronomy(all)