AC measurements and modeling of WO3 thick film gas sensors

Polycrystalline WO3 films were fabricated through thick film technology. Stimulated temperature measurements showed that the intergranular Schottky barrier is not high enough to apply the depletion approximation to evaluate the fundamental parameters related to the sensing properties. Therefore, a semi-analytical approach to the Poissonʹs equation with the complete charge density was chosen. As a result, we could estimate the dependence on frequency of both apparent permittivity and depletion region width by impedance spectroscopy.