Fabrication of Au Doped Silicon Nano Cones and Their Gas Sensing Properties to NO2 at Room Temperature

Abstract

In the present work, A new structure of silicon nano cones (SiNCs) doped by Au was successfully fabricated for room temperature (RT, 300 K) NO2 detection. And this novel structure at the nanoscale was synthesized by a combination of nanosphere lithography and metal-assisted chemical etching (MACEth). The spaces among SiNCs were helpful for diffusion and the adsorption and desorption of gas molecules. Gas sensing properties of the SiNCs doped by Au were systematically examined by measuring the change of resistance toward to NO2 with different concentration in the range of 0.25–3 ppm at RT. Experimental results showed that the gold doping could contribute to enhance gas sensitivity. The Au doped silicon nano cones sensors exhibited a low sensitivity to other gases even at high concentration. This demonstrated excellent selectivity. Moreover, the sensors showed satisfactory sensing stability and repeatability. The improvement in gas sensing properties might be attributed to the Schottky barrier between SiNCs and gold grains, and the probable gas sensing mechanism was also further discussed.