Research Of Gas Sensor Based On Composite Structrue Of Porous Silicon And Copper Oxide

With the rapid economic development,air pollution is becoming very serious.More and more researches are concentrated on gas sensor.Metal oxide semiconductor is good gas sensitive material,with high sensitivity,but it has relatively high operating temperature.It is very effective to reduce the working temperature by the low dimensional treatment of metal oxides.Porous silicon is another very good gas sensitive material,working at room temperature,but the sensitivity of it is relatively low.Composite metal oxide and porous silicon to form a new structure is very valuable.Two kinds of composite structures are prepared in this paper:one was the copper oxide/porous silicon composite structure,the other was the three stage of the copper oxide/tungsten oxide/porous silicon composite structure.In this thesis,two kinds of composite structures were prepared by physical method,and the influence of different process parameters on the morphology and gas sensing properties of the composite were studied.Mainly included the sputtering time,the heat treatment temperature,the heat treatment pressure,the heat treatment atmosphere and so on.In order to better characterize the composite structure,a variety of micro characterization methods were used,such as field scanning electron microscopy,transmission electron microscopy,and so on.In order to detect the gas sensitivity of the gas,the gas sensing test system was used.The sensitivity,response/recovery time,working temperature and selectivity of the two kinds of composite structures were tested in detail.The prepared copper oxide/porous silicon composite structure had good gas sensing properties.The working temperature was room temperature,and the sensitivity of 1ppm NO₂ was7.8,and the response/recovery time were 51s/547s.The sensitivity of 1ppm NO₂ at room temperature for the copper oxide/tungsten oxide/porous silicon reached 3.9.Both showed good gas sensitivity.At last,the gas sensing mechanism of the gas was also introduced,mainly the infuence of two kinds of different heterojunction:the role of the same type of heterojunction and trans heterojunction in the sensitivity of the lifting.