High temperature and high sensitive NOx gas sensor with hetero-junction structure using laser ablation method

In order to develop a high temperature (200/spl deg/C /spl sim/ 400/spl deg/C) and high sensitive NOx gas sensor, we developed a new structure of SiC-based hetero-junction device Pt/SnO/sub 2//SiC/Ni and Pt/WO/sub 3//SiC/Ni using a laser ablation method for the preparation of both metal (Pt) electrode and metal-oxide film. It was found that Pt/SnO/sub 2//SiC/Ni sensor show higher sensitivity to NO/sub 2/ gas compared with the Pt/WO/sub 3//SiC/Ni sensor, whereas the Pt/WO/sub 3//SiC/Ni sensor had better sensitivity to NO gas. These results suggest that selective detection of NO and NO/sub 2/ gases may be obtained by choosing different metal oxide films.