Modeling of top and bottom contact structure organic field effect transistors

Abstract

This research paper proposes analytical models for top and bottom contact organic field effect transistors by considering the overlapping of source-drain (S/D) contacts on to the organic semiconductor layer and effective channel between the contacts. The contact effect is investigated in the proposed models and further verified through two-dimensional (2-D) numerical device simulation. The electrical characteristics are obtained from the linear to saturation regime and analytical outcomes are compared with the simulation and experimental results, which shows good agreement and thus validate the models. The extracted mobilities for top and bottom contact structure include 0.129 and 0.0019 cm2/Vs, and the device resistance as 2.25 and 450MΩ and the contact resistance as 2.25 and 450 MΩ μm2, respectively. The performance difference between top and bottom contact is attributed to the structural difference and morphological disorders of pentacene film around the contacts in bottom contact device which results in higher contact resistance and lower mobility as compared to the top contact device.