Combined effects of p–n heterojunctions and active surface areas in a composite material dedicated to gas sensing applications

In this study, we analyze the unexplored field of combined effects of active surface area and p–n heterojunctions of a composite material dedicated to gas sensing applications. The used materials are thin films of mixtures of copper and zinc oxides. Individually, both copper oxide and zinc oxide shows interesting sensing performances toward a broad category of gases. The investigated films are obtained by thermal oxidation of Cu/Zn metallic multilayers. Cu/Zn metallic multilayers were obtained by using physical vapor deposition technique. The sensitivity of the composite materials, at ethanol, LPG and CO respectively, was investigated and it was observed that the highest sensitivity is obtained for ethanol. Complementary investigations (X-ray Diffraction, X-ray Photoelectron Spectroscopy and Scanning Electron Microscopy respectively) were conducted in order to understand, explain and confirm the relationship between the oxidation conditions, structure, surface morphology and the exhibit sensing properties. The experimental results indicate that the sensitivity depend on the oxidation duration.