H2 Gas Response of NiO Thin Film at Different Gas Concentrations

Abstract

Interest in H2 energy, which is one of the alternative energy sources that can meet the energy needs of the increasing world population, is increasing day by day. However, dangerous properties of H2 gas such as high flammability and explosiveness require sensitive detection of this gas. For this purpose, intensive research is being carried out on the detection of H2 gas with high response values at low gas concentrations. In this study, the structural, morphological and H2 gas sensing characteristics of NiO thin film, which grown on quartz substrate by RF sputtering. XRD results of the produced film revealed that the NiO film has a polycrystalline cubic structure with (101), (012), (110) and (113) diffraction planes. The lattice constant of the film was obtained as 4.226 nm, which differed by 1.274% from the theoretical values presented in the literature. From the special scanning XPS spectrum of the Ni element, the presence of peaks corresponding to Ni+2, Ni+3 and NiOOH on the film surface was detected. SEM images revealed the existence of a homogeneous structure on the film surface consisting of structures with grain sizes of 10-20 nm. Current changes obtained at 100, 500 and 1000 ppm H2 concentrations at 300°C showed that the produced film was sensitive to H2 gas and the current value increased as the ppm value increased. For 1000 ppm H2, the response value was 11.49, the response and recovery times were 239 and 286 seconds, respectively. Gas sensor measurements have also shown that the NiO film produced may have p-type conductivity.