Single grain and single grain boundary resistance of pentacene thin film characterized using a nanoscale electrode array

In this paper, we report on a less than 100-nm-wide nanoscale electrode array, with which the field-effect mobilities of a single grain and a single grain boundary in organic thin films are characterized. The method of fabricating the nanoscale electrode array and the evaluation results of the pentacene thin film are described. The nanoscale electrode array was fabricated by EB lithography and a liftoff process. The pentacene thin film was deposited by molecular-beam epitaxy (MBE). The resistances of a single grain and a single grain boundary were estimated to be around 10 and 100 MΩ, respectively, and the field-effect mobility was estimated to be around 1 cm2/(V s), which is almost comparable to the highest value ever reported. These results confirm that a single crystal is essential for high performance organic thin-film transistors.