Role of Plasma Parameters on the Conjugated Structure Retention in Polyaniline Thin Film

Abstract

The role of plasma parameters on the film characteristics is investigated on polyaniline thin film deposited by radio frequency (RF) plasma polymerization. A series of un-doped and iodine doped polyaniline thin films are prepared by RF discharge operating at 13.56 MHz with different discharge powers and pressure variation from 0.1 to 0.05 mbar and variation in deposition time from 20 to 40 min. A good thin film is found with a power ranging from 9 W (−28 V self bias) to 20 W (−65 V self bias) at 0.1 mbar pressure which is confirmed by fourier transform infra-red spectroscopy showing the retention of aromatic rings. In addition, iodine doping is carried out with 9 W power and 0.1 mbar pressure. The characterization of process plasma is done using Langmuir probe diagnostics and optical emission spectroscopy. A correlation has been established between film characteristics and plasma properties investigated using optical emission spectroscopy and Langmuir probe analysis. Emphasis has been given on the study of the influence of plasma parameters, particularly of the electron energy distribution function on the quality of conjugated plasma polymerized aniline film.