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 ${\mathrm{(\mu }}_{\mathrm{eff}})$ up to 0.30 cm²/V s and on/off ratios up to ${\text{5×10}}^6.$ A negative gate voltage of −50 V significantly decreases the activation energy ${\mathrm{(E}}_a)$ 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 ∼0.4% of the total number of injected carriers. Along with ${\mu }_{\mathrm{eff}}\text{∼0.3\hspace{0.17em}}{\mathrm{cm}}^2/\mathrm{V s},$ this places the intrinsic mobility in the range of tens of cm²/V s.