Gate pulse electrical method to characterize hysteresis phenomena in organic field effect transistor

Hysteresis phenomena in the current–voltage characteristics of organic thin-film transistors (OTFTs) between the up and down sweeps are commonly observed. This hysteresis behavior is strongly affected by the trapping-effect. In this work, we present a new experimental technique to study these phenomena. The technique is based on the time-dependent drain current measurements as a function of a pulsed gate voltage. The decay of the drain current observed when a gate bias is applied to the gate electrode is correlated to the trapping-detrapping effects in the silicon oxide and/or at the organic semiconductor/silicon oxide interface. We show how to use this pulse gate electrical method to characterize the true device performances (threshold voltage, carrier mobility) of petacene organic field effect transistors (OFETs) with SiO2 gate dielectric under different pulsed conditions, avoiding the pitfalls due to the presence of the hysteresis effect when using classical static data analysis methods. Moreover, we demonstrate that the charge carrier mobility is less affected by the trapping and detrapping phenomena than the threshold voltage.