Fabrication and electrical characterization of Organic Field-Effect Transistor based on CSA doped PANi-Ta2O5 nanocomposite

Top-contact, bottom-gate o rganic field-effect transistors (OFETs) based on Polyaniline (PANi)-Tantalum Pentoxide (Ta 2 O 5 ) nanocomposite doped with Camphor Sulphonic Acid (CSA) as the active semiconductor layer and Poly Methyl Methacrylate (PMMA) as the gate dielectric were investigated. Gold was thermally evaporated for the top source and drain contacts of 80-90 nm thickness with a conducting channel of 1 mm length and 1cm width. A relatively good charge carrier mobility of  0.12 cm 2 /V-s was achieved. This may be ascribed to the highly crystalline nature of the nanocomposite, the diminished contact resistance due to the long channel and the symbiosis developed between the organic semiconductor and the polymer dielectric. The smaller source-to-drain current and high saturation drain voltage may be accounted for the long channel effect. The device exhibited a threshold voltage of   -12.89 V, a moderate current on/off ratio of ~10 3 and a subthreshold swing of 9.3 V/dec. The agglomerated globular morphology of the PANi nanocomposite and the high carrier mobility can immensely contribute towards using the OFET device for room-temperature based application, particularly in the gas sensing field.