多孔硅薄膜湿度传感器的研制

【作者】 许媛媛；

【导师】 何金田；

【作者基本信息】 郑州大学 ， 测试计量技术及仪器， 2004， 硕士

【摘要】 本文用掺杂度较高的(ρ=1.5×10^-1 Ω cm或ρ=1.5×10^-2 Ω cm)、取向为（111）的P型原始硅片水热腐蚀制备了铁钝化多孔硅（iron-passivated porous silicon，缩写IPS），采用磁控溅射真空镀膜技术在IPS上镀Al膜，然后进行350℃退火处理，制成了IPS湿敏元件。另外，采用微乳-水热法制备了纯度高、粒径均匀的Fe₃O₄纳米粉，进一步制备了IPS／Fe₃O₄复合材料，并且制成了IPS／Fe₃O₄湿敏元件。 研究了IPS和IPS／Fe₃O₄的表面形貌、结构，通过不断优化制备条件(如，原始硅片的参数、腐蚀液中HF酸浓度和Fe³⁺浓度、水热处理的温度和时间等)找到了制备具有最佳表面形貌和最佳感湿性能IPS样品的水热腐蚀条件，并发现复合材料IPS／Fe₃O₄继承了IPS的形貌、结构特点。 重点研究了以IPS为感湿材料制成的湿敏元件的感湿特性，并与传统的电化学阳极腐蚀法制备的多孔硅（PS）的感湿性能进行比较。实验结果表明，IPS湿敏元件具有灵敏度高、响应快、重复性好、感湿范围宽的特点。另外，研究了以IPS为模板材料的复合式湿敏材料IPS／Fe₃O₄的感湿性能，发现IPS／Fe₃O₄湿敏元件同样具备IPS湿敏元件的特点，并且其感湿特征量相对于IPS湿敏元件有了很大的提高。由此推断，一方面，复合材料IPS／Fe₃O₄和IPS感湿性能的相似性在很大程度上取决于它们形貌上的相似性，另一方面，纳米Fe₃O₄的感湿性能在IPS这个模板材料上得以充分的发挥，这正是目前研究开发新型的复合材料成为传感器敏感材料研究的热点之一的原因所在。 探讨了IPS湿敏元件的感湿机理，建立了湿敏电容感湿模型和湿敏元件的等效电路。从理论上分析了IPS湿敏元件的感湿特性，解释并验证了实验结果的正确性和可靠性，为IPS湿敏元件用于检测湿度的可行性提供了理论依据。 本实验制得的湿敏元件与国内外同类元件相比，具有灵敏度高，响应快，测试范围宽等优点。通过工艺条件的进一步改进以及湿度标定系统和信号检出系统进行配套设计与优化，可望开发出性能优异的湿度敏感元件。更多还原

【Abstract】 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.更多还原