Carrier transport mechanisms of iodine-doped plasma polymerised N, N, 3, 5 tetramethylaniline thin films

Abstract

Plasma polymerised N, N, 3, 5 tetramethylaniline (PPTMA) thin films were produced through plasma polymerisation process using aniline derived -N(CH3)2 as a precursor where N, N, 3, 5 tetramethylaniline (TMA) was used at ambient temperature. As-deposited and iodine incorporated PPTMA layers with smooth and pinholes-free surfaces of several thicknesses (d) with structural and electrical (direct current, DC) features were evaluated via various characterisation techniques. The X-ray photoelectron spectroscopic analyses showed that carbon, nitrogen, and oxygen were present on the thin films’ surface with different possible groups CO, C-H, C-N, and CC. Both sets of PPTMA films for DC electrical assessment followed Ohmic and non-ohmic conduction in the low (VLower) and high (VHigher) voltage areas, respectively. At the VHigher region for both films, space-charge-limited conduction (SCLC) tackle is found to be operative, and the current density (J) increases with T and d. The total trap concentration, the free carrier concentration, and the carrier mobility of PPTMA thin films were changed from 4 ± 0.05 × 1030 m−3, 2 ± 0.04 × 1021 m−3 and 1.3 ± 0.02 × 10−13 m2 V−1s−1 to 1.2 ± 0.06 × 1027 m−3, 3.7 ± 0.03 × 1022 m−3, and 1.5 ± 0.05 × 10−12 m2 V−1s−1 respectively, due to the gradual iodine addition. The activation energy (ΔE) values of iodine-doped and as-deposited PPTMA films at an applied voltage (VA = 2 V) from lower (TL) to higher (TH) temperatures were ~ 0.11 to ~ 0.73 eV (at VA =10 V, 0.10–0.75 eV) and 0.19–0.83 eV (at VA =10 V, 0.18–0.87 eV), respectively. The conductivity of iodine-doped PPTMA films was higher compared to the as-deposited ones.