Synthesis and Characterization of Schottky Diodes from Polyaniline Doped with Trifluoroacetic Acid

In this paper we report the fabrication of Schottky barriers using polyaniline (PANI) doped with trifluoroacetic acid (TFA). The PANI doped with TFA (PANI-TFA) was prepared by chemical oxidative polymerization using an indirect synthetic route known as doping-dedoping-redoping. The structural, morphological, optical and thermal properties of the obtained doped polyaniline (PANI-TFA) were studied by FTIR, SEM, UV−Vis-NIR, and TGA and DSC, respectively. Its electrical conductivity was measured at room temperature with a four-probe method. FTIR and UV−Vis-NIR analysis confirmed the structure and the doping of the emeraldine base by the trifluoroacetic acid. Four-probe measurements showed that the electrical conductivity of the PANI-TFA sample was around 0.226 S/cm. In addition, a Schottky diode with configuration Al/PANI-TFA/Ag was fabricated. Current–voltage (I−V) and capacitance–voltage–frequency (C−V−f) measurements were used to characterize the fabricated Al/PANI-TFA/Ag device. It was found that the (I−V) plot was nonlinear and asymmetric and the (1/C²−V) plots were almost linear in reverse bias voltage indicating that the Al/PANI-TFA/Ag device exhibited behavior similar to a diode with rectification behavior and followed the modified Schottky diode equation. The diode parameters, including the ideality factor, barrier height, saturation current and carrier concentration, were calculated using the modified Shockley equation.