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 (μeff) up to 0.30 cm2/V s and on/off ratios up to 5×106. A negative gate voltage of −50 V significantly decreases the activation energy (Ea) down to 0.143 eV near room temperature. Using this value of Ea and a simple model, we find the number of free carriers is only ∼0.4% of the total number of injected carriers. Along with μeff∼0.3 cm2/V s, this places the intrinsic mobility in the range of tens of cm2/V s.