Organic Thickness Dependence of Organic Field-Effect Transistor Devices based on Pentacene

The electrical properties of OFET devices were studied as a function of the thickness of pentacene active layer. A bottom gate, top contact structure was investigated by measuring the electrical characteristics with 100 pm channel length and comparing with the results of 2-D numerical simulation at various organic thickness layers. The saturated current at same gate voltage was increased when the pentacene film was thicker. From the simulation cross-section results, this is due to the carrier has to move from source to drain electrodes through the conducting channel and across the whole thick of active layer. However, these increasing currents are not only depending on conducting layer but also strongly depending on the increasing of threshold voltage when organic thickness is increased.