THERMAL AND AC ELECTRICAL PROPERTIES OF THIN FILMS PREPARED FROM n-BUTYL METHACRYLATE BY A CAPACITIVELY COUPLED PLASMA REACTOR

Plasma-polymerized thin films of n-butyl methacrylate (PPnBMA) have been deposited on to glass substrate in an aluminium/PPnBMA/aluminium configuration by a capacitively coupled glow discharge reactor. The field emission scanning electron microscope and atomic force microscope images of PPnBMA thin films showed a flat, uniform and continuous surface. With increasing deposition time the root mean square roughness of the PPnBMA thin films increases. The differential thermal analysis and thermogravimetric analysis demonstrated that PPnBMA was thermally stable up to about 476 and 500K in air and N2 environments, respectively. The alternating current (AC) electrical conductivity (σAC) and dielectric properties of the PPnBMA thin films of thickness 120nm were investigated in the frequency region from 102–106Hz at various temperatures. It was found that the mechanism dependable for the conduction process in PPnBMA is hopping. The trend of dielectric constant ascends with ascending temperature and descends with frequency. The dielectric loss tangent is seen to increase with frequency and attains a maximum loss peak at around 105Hz and above this frequency it decreases. The plot of relaxation time against the reciprocal of absolute temperature for PPnBMA thin film yields the activation energy for dielectric relaxation at 0.05eV. Cole–Cole plot exhibits little distorted semicircle which also indicates nearly Debye type relaxation process in this film.