Structural properties and temperature dependence dielectric properties of PVA-Al${}_2{O}_3$ composite thin films

Thin films of polyvinyl alcohol (PVA)–aluminium oxide(Al${}_2{O}_3$) composite have been made by solution casting method. XRD, FESEM and FTIR techniques were used to characterize the prepared composite films for structural analysis. The existence of M–O bond was identified by FTIR. XRD study reveals that PVA composite has polycrystalline in nature. The morphological study shows the dispersion of Al${}_2{O}_3$ particles on the surface of thin films. The effect of temperature and frequency on dielectric properties of PVA–Al${}_2{O}_3$ composite was investigated and improvement of dielectric properties with temperature observed. AC conductivity is increased with temperature and maximum conductivity of $3.20\times {10}^{-5}$ S/cm for PVAl-10% at 353 K is observed. Activation energy is evaluated from Arrhenius plot and found to lie in between 0.05 and 0.16 eV. Frequency exponent factor 's' for Pristine PVA and PVAl-10% was calculated and found to lie in between 0 and 1. Impedance plots depict the semicircle at higher frequencies and residual tail at the lower frequencies and value of Rb is found to decrease till PVAl-10% and increased for further concentration. The prepared PVA–Al${}_2{O}_3$ composites could be used in optoelectronic devices and thin film transistors as high k layer due to their high dielectric constant with low dielectric loss.