Optical gas sensitivity of a metaloxide multilayer system with gold-nano-clusters

In this paper we report on the optical gas sensitivity of a sputtered multilayer system consisting of In x O y N z thin films and gold-nano-clusters. This system shows a reversible change in the optical absorption (increase or decrease of absorbance) during exposure to reducing or oxidizing gases in air. The gold-nano-clusters are randomly distributed on and inside the multilayer system. Here, we demonstrate the optical gas sensitivity at a temperature of 400 °C and three exemplary gas samples: carbon monoxide in dry synthetic air, nitrogen dioxide in dry synthetic air and hydrogen in dry synthetic air. We show that the incorporation of the gold-clusters leads to a broad absorption peak in the range of visible light due to the excitation of localized surface plasmons. The corresponding resonance wavelength is shifted by gas exposure that in turn changes the optical behavior of the multilayer system.