Gas sensitivity modulation of oxide thin films by means of an electrical method

To enhance the sensitivity of a metal oxide-based gas sensor, we introduce a novel electrical method that relies jointly on the use of impedance and an applied DC bias. We used polycrystalline ZnO–NiO composite thin films prepared by pulsed layer deposition as CO gas sensor material. The applied DC bias lowers the interface barrier between oxide grains and thereby enhances the sensitivity. Our approach enhances the sensitivity to CO gas by approximately 200% more than a conventional DC method. The enhancement effect is more pronounced when the CO concentration is lowered. This method offers an efficient characterization tool for modulating the sensitivity of gas sensors using semiconducting metal oxides.