Dendritic composite array of silicon nanowires/WO3 nanowires for sensitive detection of NO2 at room temperature

Abstract Dendritic composite array of silicon nanowires (SiNWs)/WO 3 nanowires was prepared for highly sensitive gas sensor application. WO 3 nanowires were grown directly on the top section of SiNWs fabricated by metal-assisted chemical etching (MACE), through thermal annealing of pre-deposited W film to obtain dendritic SiNWs/WO 3 nanowires array. At room temperature (RT), the composite sensor shows obviously enhanced sensing response to NO 2 in comparison to pure SiNWs sensor. The response value upon 5 ppm NO 2 exposure is more than four folds of that from SiNWs. Meanwhile, good selectivity as well as perfect dynamic characteristic, especially ultrafast response (response time 2 ) is achieved for the composite sensor. The underlying sensing mechanism of the composite sensor is analyzed in detail.