[en] Various fabrication techniques and characterization methods have been utilized to successfully demonstrate plasmonic effects in a wide range of applications such as metamaterials, photovoltaic devices, cancer therapy, quantum optics, etc. The plasmonic nanostructures can be used for efficient conversion of plasmon energy to an electrical signal or vice versa. Various structures have been adopted to utilize this effect in diode and transistor configuration.The combined process of plasma polymerization and magnetron sputtering for preparing stable plasmonic material emerges as a convenient method that is utilized in self-powered light harvesting devices.In this work, we present the synthesis of gold-polyaniline (Au-PPA) nanocomposite with gold nanoparticles (AuN) using plasma based processes to fabricate plasmonic thin film transistor (PTFT). Gold nanoparticles are distributed throughout the thin film. Material characterization of the nanocomposite thin film has been carried out using standard techniques such as FTIR, UV-Visible spectroscopy, and SEM. Gold nanoparticles (AuN) in the polymer matrix are found to be of different shapes and sizes that can be tailored easily with deposition parameters, which is confirmed by the UV-Visible spectroscopy as they show different plasmon absorption bands in the absorption spectra. The nanocomposite is coated over silicon oxide (SiO₂) as gate dielectric material where the linear channel of the transistor is of variable length (30, 40, 50, 60, 80 μm) with gold (Au) source and drain electrodes. The basic electrical characteristics and spectral photoresponse of the transistor are studied using Keithley source-meter, OFET test board, and suitable light sources. Appreciable change in the drain current at different gate biases has been observed with variation in the intensity of the white light. The photoresponse of the device is the result of light absorption due to localized surface plasmon resonance (LSPR) of the gold nanoparticles (AuN) and subsequent charge generation and injection by direct charge transfer process to the polymer semiconductor. (author)