Field-effect transistor on pentacene single crystal

We report on the fabrication and characterization of field-effect transistors (FETs) on single-crystal pentacene. These FETs exhibit hole conductivity with room-temperature effective mobility (mu(eff)) up to 0.30 cm(2)/V s and on/off ratios up to 5x10(6). A negative gate voltage of -50 V significantly decreases the activation energy (E-a) down to 0.143 eV near room temperature. Using this value of E-a and a simple model, we find the number of free carriers is only similar to0.4% of the total number of injected carriers. Along with mu(eff)similar to0.3 cm(2)/V s, this places the intrinsic mobility in the range of tens of cm(2)/V s. (C) 2003 American Institute of Physics.