Performance and degradation in single grain-size pentacene thin-film transistors

Submicron channel-length pentacene thin-film transisors (TFTs) were fabricated by electron beam lithography and a lift-off process. It was found that pentacene TFTs operated in the submicron channel length, but an enhancement of the off-stage leakage current and a large hysteresis were observed. By further investigation, we found that the large hysteresis observed in the submicron channel length was due to the moisture in the air. We also found a non-moisture-related degradation, in addition to a moisture-related one, by a time-dependent degradation measurement. It is of great importance both to avoid the moisture invasion and to reduce charging sites in the channel for reliable pentacene TFTs.