Temperature and electric-field dependence of the mobility of a single-grain pentacene field-effect transistor

A single-grain organic field-effect transistor (OFET) of pentacene with a 1 mu m channel length of top-contact electrodes is demonstrated in a wide range of temperatures from 300 down to 5.8 K. No hysteresis behavior was observed in the transfer characteristics throughout the entire temperature range. The saturation mobility and on/off ratio are estimated at 1.11 cm(2)/V s and 10(7) at 300 K and 0.34 cm(2)/V s and 10(5) at 5.8 K, respectively. The nonmonotonic temperature dependence of the mobility indicates a bandlike transport at high temperatures. The electric-field dependence of the mobility in the single-grain OFET does not show a Poole-Frenkel-like behavior. This indicates that Poole-Frenkel-like behavior observed in conventional OFETs can be attributed to the disorder of molecules; single-grain OFET is free from such disorders. (c) 2006 American Institute of Physics.