Low-voltage pentacene thin-film transistors with Ta2O5 gate insulators and their reversible light-induced threshold voltage shift -: art. no. 132101

We have fabricated pentacene thin-film transistors using Ta2O5 films prepared by magnetron reactive sputtering as gate insulators. These transistors exhibit good electrical characteristics at an operating voltage as low as 5 V, with a field-effect mobility of 0.32 cm(2)/Vs, an on/off ratio of 10(4), and a subthreshold slope of 0.5 V/decade. We have also investigated the optical properties of these transistors and observed a reversible light-induced threshold voltage shift. Under illumination, the threshold voltage shifts towards the positive direction while the field-effect mobility and on/off ratio remain almost unchanged. In the dark, however, the threshold voltage can slowly be restored to its original state. At a gate voltage of -5 V, the transistors show a broadband responsivity of 3.7 A/W after illumination at 60 mu W/cm(2) for 10 min. (C) 2005 American Institute of Physics.