Decoration of Gold Nanoparticles on TiO<sub>2</sub> Thin Films for Enhanced Response of Ethanol Gas Sensors

Abstract

This work investigated the decoration of the gold (Au) nanoparticles (NPs) on the TiO2 thin films for the applications in ethanol gas sensors. The Au-decorated TiO2 thin films (Au-TiO2) were prepared by the DC magnetron sputtering on the silicon (100) wafers and alumina substrates, interdigitated with Au electrodes. The distribution and size of Au nanoparticles were controlled by varying the sputtering time. Morphologies and element composition of the Au-TiO2 films were examined by field-emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDX) respectively. The FE-SEM micrographs when the sputtering time was increased, the average size of the Au NPs was also increased. On the other hand, the distribution of the Au NPs was decreased. The change in size and distribution of the Au NPs consequently improved the response of ethanol gas sensors. The prepared Au-TiO2 was tested, in comparison with TiO2 reference films, as the ethanol sensors at 250-350oC in 50-1,000 ppm gas concentration. The results showed that the TiO2 thin film with Au-decorated at 6 sec sputtering time yielded the highest response of 514 at 350oC operating temperature and 1,000 ppm gas concentration.