ZnO vs ZnO/Au thin films: a comparison of sensing properties in photo-activation mode

In this work, we analyzed in photo-activation mode the difference between two thin film sensors based on pure ZnO and on cluster gold decorated ZnO. An increasing interest towards photo-induced chemoresistive properties of metal-oxides semiconductors has motivated the research. In fact, many scientific articles deal with the properties of chemoresistive semiconductor under light, with energy of the order of magnitude the band gap of the semiconductor. For this reason, we have tested the two types of ZnO thin films to several gases, at room temperature under different wavelengths illumination. The obtained results showed some interesting features of the two sensing materials, such as a better selectivity of gold decorated ZnO than pure ZnO thin films, and, more importantly, a selective response of former to NO2 under green light irradiation.