Performance Comparison of Low-Voltage non-Ionic Gel Organic Field Effect Transistors with Gold and PEDOT:PSS Gate Electrodes

Abstract

Low-voltage non-ionic gel organic-field effect transistors (NIGOFETs) with two kinds of gate electrode materials namely gold (Au) and poly(3,4ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) formulation were fabricated in top-gate bottom-contact geometry to investigate the effects of gate electrodes on the electrical performance of the OFETs. In addition, three kinds of gate dielectrics were used for both types of transistors to understand the effects more thoroughly. As a result, it can be deduced from the data that NIGOFETs with Au gate electrodes (Au-NIGOFETs) display better performance considering higher mobility and on-to-off current ratio (ION/IOFF) as well as lower Subthreshold Swing (SS) of them. Besides, the threshold voltage (VTH) effects-free drain currents (IDS) of the Au-NIGOFETs surpasses those of the PEDOT:PSS formulation gated NIGOFETs (Pedot-NIGOFETs). This is probably due to having greater WF gate electrode (in our case Au) provides less injection barrier eventually leads to relatively unimpeded charge transportation. Nevertheless, Au-NIGOFETs interestingly proves to have further negative VTH and lower off-current (IOFF), which may be attributed to lower electrical resistivity (ρ) of the Au leading to denser charge carrier traps formation along with intensified charge carrier induction at the semiconductor-dielectric interface when the gate-to-source voltage (VGS) is less than VTH. However, because of the same reason, when VGS exceeds the VTH for example, IDS of Au-NIFOFET1 starts to increase in such a quick manner that enabling it to have higher ION/IOFF and lower SS.