Organic field-effect transistors with single and double pentacene layers

We report the characterization of field-effect transistors fabricated within individual grains of single and double pentacene layers grown on silicon oxide. Field-effect mobilities are found to increase with increasing gate voltage and exhibit a thermally activated form for the temperature dependence. These characteristics can be explained by the multiple trapping and release model. The mobilities of double-layer devices are one order of magnitude higher than those of single-layer devices. Possible origins of the traps are discussed. The geometry of these ultrathin devices makes them suitable for sensing applications.