Structural, Morphological and Sensor Properties of the Fractal-Percolation Nanosystem ZnO/NiO

ZnO/NiO fractal-percolation nanosystems have been sensitized using a newly developed three-step technology. During the first stage, ionically sputtered Zn vapors have been deposited under near-equilibrium condensation conditions. In the second stage, Zn layers have been oxidized in air atmosphere, and during the final stage, a NiO layer has been deposited onto the ZnO surface using reactive magnetron sputtering. Gas sensor tests have been performed by measuring current–voltage characteristics of the fractal-percolation nanosystems in air containing methanol or methane. It has been shown that the shape of the I–V curve depends on the reactive gas nature, rendering the possibility to differentiate between different gases, which is an important step to increase sensor selectivity.