DIELECTRIC PROPERTIES OF PLASMA POLYMERIZED N,N,3,5 TETRAMETHYLANILINE THIN FILMS

Abstract

Plasma polymerized thin films of aluminium/thin film/aluminium configuration were deposited at room temperature by a parallel plate capacitively coupled glow discharge reactor using N,N,3,5 tetramethylaniline (TMA) as a precursor. The infrared spectroscopic analyses revealed that plasma polymerized TMA (PPTMA) films contained an aromatic ring structure with NC and CH side groups, presence of C = O was also evident. The differential thermal analysis and thermogravimetric analysis of PPTMA thin film was thermally stable up to about 505 K. The scanning electron microscopy of PPTMA thin film showed a smooth, flawless and pinhole free surface. The capacitance and ac electrical conductance of PPTMA thin films were measured as functions of frequency (100 < f < 105 Hz) and temperature (300 < T < 450 K). The electrical conductivity is more dependent on temperature in the low frequency region than that in the high frequency region. In PPTMA thin films the conduction may be dominated by hopping of carriers between the localized states at low temperatures and thermally excited at the high temperatures. The activation energies are estimated to be about 0.05 eV in the low temperature and 0.23 eV in the high temperature. Dielectric constant decreases with the increase of frequency and that decreases with the increase of temperature but dielectric loss increases with increasing frequency with a minimum in the low frequency region. The temperature-dependence of the Cole-Cole diagram shows the existence of distribution of dielectric relaxation times in the PPTMA thin films.