Fabrication and Characterization of CuO Nanoparticles/ZnO Nanorods Heterojunction Structure for Room Temperature NO Gas Sensor Application

This paper reports the room temperature sensing of NO gas by a novel oxide semiconductor p-n heterojunction structure composed of p-type CuO nanoparticles and n-type ZnO nanorods, which were fabricated using solution-based synthesis methods. The transport behavior and NO gas sensing properties of the hybrid CuO nanoparticles/ZnO nanorods heterostructure were characterized. The oxide heterojunction structure exhibited definite rectifying diode-like behavior at room temperature. When the oxide p-n heterojunction structure was exposed to the acceptor gas NO in dry air, an abrupt decrease in the forward diode current of the p-n junction was observed. The NO gas sensing response of the CuO nanoparticles/ZnO nanorods heterostructure at 2 V was as high as 265% for a NO concentration of 10 ppm even at room temperature and increased linearly with increasing NO gas concentration in the range of 3-10 ppm. The experimental results indicated that this type of oxide heterostructure can be used effectively in a range of gas-sensing applications because of its simple solution-based processing and room temperature performance.