Rubrene polycrystalline transistor channel achieved through in situ vacuum annealing

The authors report on the rubrene polycrystalline film growth for its thin film transistor (TFT) applications. Amorphous rubrene thin film was initially obtained on $200-nm$-thick $SiO2∕Si$ substrate at $40°C$ in a vacuum chamber by thermal evaporation but in situ long time postannealing at the elevated temperatures of $60–80°C$ transformed the amorphous phase into crystalline. Based on an optimum condition to cover the whole channel area with polycrystalline film, the authors have fabricated a rubrene TFT with a relatively high field effect mobility of $0.002cm2∕Vs$⁠, an on/off ratio of $∼104$⁠, and a low threshold voltage of $−9V$⁠.