Study On Gas Sensors Based On Silicon Nanowires/Tungsten Oxide Nanowires Composite Structure

Air pollution is an important aspect of environmental pollution,the NO₂ gas in the air will cause serious damage to the human body.Therefore,the gas sensor which can work at room temperature and has low energy consumption and high sensitivity has attracted the attention of many researchers.So far,silicon nanowires and tungsten oxide nanowires have been considered to be the most potential semiconductor gas sensitive materials due to their characteristics,respectively.Based on the above background,this paper constructed a new type of gas sensor based on silicon nanowires/tungsten oxide nanowires,and the relevant experimental and theoretical were studied.In the experiment,a type of silicon nanowires with highly ordered arrays was prepared by using metal assisted chemical etching and self assembly of nano spheres in n single crystal silicon wafer.Then,a layer of metal tungsten film was deposited on the surface of silicon nanowires by magnetron sputtering.Through the tube type heat treatment furnace,the preparation of silicon nanowires/composite tungsten oxide nanowires,and the preparation parameters and gas sensitive properties in the process of exploration and testing.Finally,the gas sensing mechanism of the composite structures of silicon nanowires and silicon nanowires/tungsten oxide nanowires are discussed respectively.As the results shown,in the process of preparation of silicon nanowires,the morphology of H₂O₂ concentration and etching time on silicon nanowires may have effect,agglomeration effect of nano line top increased with the increase of the concentration of H₂O₂ and etching is gradually serious,which affects the surface area and gas diffusion channels,resulting in a decline in gas sensitive properties.The suitable oxidation rate is a key factor in the silicon nanowires composite tungsten oxide nanowires,the reaction temperature and oxygen flow rate is too high will cause the metal tungsten oxide nanowires can speed up the rate of growth was completely oxidized,the reaction temperature and oxygen flow rate is too low will cause the metal tungsten oxide nanowires were slow,poor growth of.The interface of silicon nanowires/tungsten oxide nanowires will form the same type heterojunction,and the growth of depletion layer width in NO₂ gas plays an important role in enhancing the gas sensing properties.