THICKNESS DEPENDENT AC CONDUCTIVITY OF PLASMA POLY (ETHYLENE OXIDE) THIN FILMS

Abstract

The properties of thin film polymers such as low dielectric constant, high thermal and photo balance, high chemical resistance and high optical transmittance are widely used in optic and microelectronics. In this work, plasma poly(ethylene oxide) (pPEO) thin films in different thicknesses were deposited between Aluminum (Al) electrodes on glass substrates by plasma assisted physical vapor deposition (PAPVD) technique at Argon plasma under 10(-3) Torr. The plasma was produced at 5 W by magnetron connected to RF power supply. The ac measurements of the samples were made were in the frequency range 10(-1) Hz - 10(7) Hz and in temperatures from 193 to 353 K with increments of 10 K. Thickness dependent AC conductivity of pPEO thin films can be interpreted by empirical relation sigma (omega) alpha omega(n) where omega is the angular frequency and n is the parameter. Frequency, temperature and thickness dependence of AC conductivity showed that there were oligomers and free radicals with different sizes produced by plasma polymerization of PEO. The thickness dependence of AC conductivity of plasma PEO samples can be evaluated to adjust AC conductivity and also to adjust the DC-like conductivity which is a results of drift of free charge carriers or the orientation polarization of long oligomers. Three different relaxation mechanisms depending on the film thickness were observed. The effect of the dead layer in the polarization region of long oligomers was determined.