Interface trap level in top-contact pentacene thin-film transistors evaluated by displacement current measurement

The interface trap level in top-contact pentacene thin-film transistors (TFTs) is obtained by displacement current measurement (DCM) during device operation at temperatures ranging from 260 to 340 K. The carrier injection voltage at the source electrode (VinjVinj) was measured from the displacement current and found to be independent of temperature, suggesting an Ohmic contact at the Au source electrode/pentacene interface. On the contrary, the threshold voltage (VthVth) depended on the temperature. The interface trap level at the pentacene/gate dielectric interface was estimated as 36 meV from the temperature dependence of the interface trap density. By using the DCM method, it becomes possible to demonstrate the carrier injection and transport properties of top-contact pentacene TFTs.