A systematic study of the impact of etching time to the sensitivity of SiNW sensor fabricated by MACEtch process

In this paper, silicon nanowires (SiNWs) was fabricated by a combination of metal-assisted chemical etching (MACEtch) and nanosphere lithography. We get the silicon nanowires with different specific surface area by changing the etching time. The microscopic structure of the silicon nanowires is observed by field emission scanning electron microscope (FESEM). The gas sensing performances of the SiNWs with different specific surface area have been systematically examined by measuring the resistance change towards the concentrations of NO2 in the range of 1-5 ppm at room temperature (RT, 300 K), the gas sensor composed of SiNWs showed perfect gas sensitive property and possessed a short response-recovery time. The main reason of these excellent attributes is quite likely that high specific surface area of the SiNWs, and NO2 sensing mechanism of the SiNWs was also further explained, which can be attributed to the oxygen in the air and detected NO2 extract electrons from the surface of the SiNWs, and the resistivity of SiNWs changed with the changing of space-charge layer under the of SiNWs surface.