Study Of The Humidity Sensing Properties Based On Nanosilicon

With developing of modern information technology, the continuous improvement of accuracy of information access in the field of monitoring is requested. Therefore, the sensing devices with high sensitivity, stable structure and small size are increasingly demanded. In particular, the response speed, stability and sensitivity of humidity sensors are very essential for humidity detection and monitoring in the field of environmental monitoring, which provide a broad prospects and challenges for the research and development of humidity sensor.The research is based on nano-Silicon materials which have good Structural characteristics and surface activity. Fabrication of Silicon nanomaterials, development of nano-silicon humidity sensor test system, test of sensing properties of nano-silicon humidity sensors and surface modification of nano-silicon were investigated in our thesis. It mainly contains the following works:First, the silicon nanowire arrays with different structures were fabricated by chemical wet etching technology. The surface morphology of as-prepared silicon nanowire arrays was characterized. It laid the foundation for the application of humidity sensor and provided abundant sensitive materials for the fabrication of nano-silicon-based humidity sensors.Second, the nano-silicon-based humidity sensors were fabricated by micro-processing technology. The silicon nanowires with large specific surface area and good surface activity were used as humidity sensitive materials. The humidity response characteristics of as-fabricated humidity sensors were tested by using the self-designed humidity test system. The test results showed that the room temperature response and recovery time of nano-silicon-based humidity sensors were very short, about 50 seconds and 60 seconds, respectively. Moreover, the sensitivity, stability and recoverability properties of the humidity sensors can be compared to the current commercial sensors.Last, a preliminary study on plating nickel modification on the silicon nanowires was carried out by using the hydrophilic property of Nickel-metal surface to improve the response time and sensitivity characteristics of humidity sensors. Plating nickel on surface of silicon nanowires was was implemented successfully by the electroless nickel process. The humidity response characteristics of nickel-silicon-based nanowires humidity sensors were tested. The results showed that the response time of the humidity sensors was significantly improved about 50 seconds after plating nickel modification, and its linearity has also been improved obviously.