AC electrical properties of vacuum-evaporated SiO/SnO2films

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Abstract
Measurements were carried out on the AC electrical properties of vacuum-evaporated SiO/SnO2 films having different compositions at temperatures between 173 K and 413 K and over the frequency range 200 Hz-1 MHz. The measured conductivity shows a frequency dependence σAC ∝ ωs with s having different values for higher and lower temperatures. AC conductivity at higher frequencies may be due to electronic hopping. The Elliott (1977) model satisfactorily explains the frequency dependence of conductivity and the temperature dependence of s. The value of the dielectric constant remains unchanged at high frequencies irrespective of temperature change, whereas its value increases at higher temperature with the decrease in frequency. Although the capacitance of the sample shows an increase in value with the increase in temperature within the lower frequency range (103–105 Hz), its value remains fairly constant at low temperatures within the measured frequency range. Tan δ, the dielectric loss has been found to increase with increase in temperature and decrease in frequency.