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The Development Of Porous Silicon Thin-film Humidity Sensor

Posted on:2005-11-08Degree:MasterType:Thesis
Country:ChinaCandidate:Y Y XuFull Text:PDF
GTID:2208360125957769Subject:Measuring and Testing Technology and Instruments
Abstract/Summary:PDF Full Text Request
Iron-passivated Porous Silicon (IPS) was fabricated by hydrothermally etching highly doped (p =1.5 10-1 cm or p =1.5 10-2 cm), (111) oriented single crystalline silicon wafers. The electrodes were formed by magnetron sputtering aluminium at 150 C and subsequently heat-treated at 350C. Thus an IPS humidity-sensitive device was brought out. In addition, Fe3O4 nano-crystal with high purity and even particle size was prepared by combinatorially hiring microemulsion and hydrothemal method. Furthermore, compound material of IPS/Fe3O4 was used as humidity sensitive material to detect humidity.Morphologies of IPS and IPS/Fe3O4 prepared under different etching conditions were studied, and through which the most suitable condition for the preparation process were obtained. Besides, it was showed that IPS/Fe3O4 inherited the morphology of IPS.Humidity sensing properties of IPS humidity-sensitive device were mainly investigated, and were compared with those of normally electrochemical-anodized porous silicon (PS). It was found that humidity device based on IPS exhibits high sensitivity, fast response, good repetition and wide sensing range. Aside from it, it was discovered that compound material of IPS/Fe3O4 based on IPS possesses the humidity sensing properties of IPS, and eigenvalues of humidity sensing were improved greatly. It was concluded that, on the one hand, the similarity of humidity sensing properties lied on the similarity of their morphologies, on the other hand, humidity sensing properties of Fe3O4 nano-crystal based on IPS was adequately exerted. This is thought of as reasons why compound materials are hotspots in research field of sensing material of sensors.Humidity sensing mechanism of IPS was primarily studied, and both humidity sensing capacitance model and equivalent circuit of humidity sensing device were established. Through the model and the equivalent circuit, humidity sensing properties of IPS were analysed theoretically, and experiment results wereexplained and validated. Therefore, theories were provided to the feasibility of using IPS as humidity sensing material.Compared with the same kind sensors from home and aboard, the humidity sensing devices fabricated in this experiment enjoy the advantages of high sensitivity, fast response, good repetition and wide sensing range. Humidity sensor with high-quality are to be brought out through optimization of device-fabricated technics and modular design for humidity calibration system and signal detection system.
Keywords/Search Tags:sensor, humidity sensitive device, humidity sensing property, porous silicon, Hydrothermally etching, iron-passivated, compound material
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