Thickness Dependent Dielectric Loss of Plasma Poly (Ethylene Oxide) Films
Abstract
Dielectric properties of plasma poly (ethylene
oxide) (pPEO) thin film samples were investigated at room temperature. The thin
film samples with different thicknesses were deposited by plasma assisted
physical vapor deposition (PAPVD) technique at 5 W plasma discharge power. The
thicknesses were 20, 100, 250, 500 nm. It was observed that dielectric constant
increases with increasing thickness. The relaxation times determined by
dielectric loss-frequency relation, shift toward higher frequencies with
increasing thickness. In addition film thickness, heating processes were
defined as another parameter. By this purpose, thin film samples were heated
and cooled, respectively. It was observed that maxima and minima of dielectric
loss at cooling process take place at lower frequencies in comparison with
frequencies at which maxima and minima were detected at heating process. These
results may show the effect of dead layer at thinner films. After heating
process, it was observed from behavior of dielectric constant and dielectric
loss that the crosslinking density increases by heating effect. This effect may
cause additional reactions between free radicals which are production of PAPVD.
Moreover, dynamic glass transition temperatures were calculated. These
temperatures prove the effect of dead layer approximation.
Keywords
Plasma poly (ethylene oxide),thin film,dielectric properties,dynamic glass transition temperature
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