Fabrication and characterization of a ZnO quantum dots-based metal-semiconductor-metal sensor for hydrogen gas

This paper reports an interdigitated metal-semiconductor-metal (MSM) based hydrogen gas (H-2) sensor using colloidal zinc oxide (ZnO) quantum dots (QDs) as the sensing material. The active layer is obtained by spin coating of as-synthesized colloidal ZnO QDs on a SiO2/Si substrate in which the SiO2 layer is grown by oxidation of the Si substrate. The surface morphology of a ZnO QDs -based active film is measured using scanning electron microscopy (SEM) and atomic force microscopy (AFM) support for enhanced gas response. The change in current is measured for different concentrations of H-2 gas at 175 degrees C in an ambient air atmosphere. Reasonably good gas responses of similar to 41% for 1% H-2 gas and 83.2% for 4% H-2 gas have been obtained in ambient air condition. A high selectivity of the proposed sensor with respect to ammonia, sulfur dioxide and organic vapours such as acetone, methanol, chlorobenzene, and chloroform has also been achieved due to nanostructure ZnO films.