Simultaneous determination of refined values of mobility, channel and contact resistance in organic field-effect transistors utilizing the four- and three-probe methods

Abstract Accurate determination of charge carrier mobility is a critical aspect in an organic field-effect transistor (OFET) as it is tightly correlated to the development of new materials, better device designs and improved fabrication methods. The presence of high contact resistance at the metal–organic semiconductor interface introduces an intrinsic error in the extraction of charge carrier mobility. In this report, electrical circuit analysis for the determination of the refined channel mobility, total contact resistance and channel resistance values is showcased for a poly(3-hexylthiophene) OFET with bottom-gate bottom-contact architecture. The process of determination is based on the combination of the conventional four-probe and three-probe measurement techniques. These two techniques are used in conjunction to assess refined mobility values in the channel region. This is followed by the determination of total contact resistance and channel resistances. The results show that, at a fixed drain current, mobility increases with the gate voltage while both the contact and channel resistances decrease.