中等孔径多孔硅基底电化学法可控生长ZnO和WO3微纳米晶体及其构建室温NO2气敏传感器的研究

Aiming at the problems that the high gas sensitivity and fast response/recovery features can not coexist for the traditional type of porous silicon (macro-PS and meso-PS) due to the high porosity and high orderly channels cannot be satisfied simultaneously for their microstructure, additionally ZnO gas sensor and WO3 gas sensor based on the traditional substrate have a high working temperature (about 200-400ºC), the preparation of a intermediate-sized porous silicon (intermediate-PS) with ordered channels and high porosity by electrochemical method is proposed in this project. Afterward, the ZnO micro/nanocrystals and WO3 micro/nanocrystals will be deposited onto the intermediate-PS substrate by controllable electrochemical method. The growth conditions and the growth mechanism of the ZnO micro/nanocrystals and WO3 micro/nanocrystals with different morphologies on the intermediate-PS will be discussed. The gas-sensing properties and the gas-sensing mechanism of the intermediate-PS, the ZnO/intermediate-PS nanocomposite and the WO3/intermediate-PS nanocomposite to some gases including NO2 will be investigated. By optimization design, the new types of ZnO/intermediate-PS nanocomposite gas sensor and WO3/intermediate-PS nanocomposite gas sensor which are easy compatible with silicon integrated circuit system and can be used to detect NO2 gas quickly and effectively at room temperature will be fabricated. This study will provide important theoretical and experimental basis for the development of high-performance NO2 gas sensor which can be easily integrated and operated at room temperature with low power consumption.

本课题针对传统类型的硅基多孔硅（大孔硅和介孔硅）因微观结构不能同时满足高孔隙率和孔道高度有序性而难以实现高气敏灵敏度与快速响应/恢复特性共存，基于传统基底的ZnO和WO3气敏传感器工作温度较高（约200-400ºC）等问题，提出以电化学法制备具有中等孔径且孔隙率较高的有序多孔硅（中孔硅），然后以中孔硅作为基底在其表面采用电化学法可控生长ZnO和WO3微纳米晶体，探讨不同形貌的ZnO和WO3微纳米晶体在中孔硅上的生长条件和生长机理，研究中孔硅、ZnO/中孔硅和WO3/中孔硅纳米复合材料对NO2等气体的气敏性能和气敏机理，通过优化设计，构建新型的易与硅基集成电路系统相兼容的ZnO/中孔硅和WO3/中孔硅纳米复合材料气敏传感器用于实现在室温下对NO2气体的快速有效检测。本课题的研究将为开发能够在室温下工作的低功耗易集成的高性能NO2气敏传感器提供重要的理论与实验基础。

大气污染问题日益严重。有毒有害气体二氧化氮（NO2）危害人类健康与环境安全。传统气敏传感器以陶瓷为基底，存在着工作温度高、功耗大、与硅基集成电路不兼容等缺点。以具有室温气敏性能的多孔硅为基底，电化学沉积ZnO、WO3等微纳米晶体，构建新一代纳米复合材料气敏传感器实现对NO2的快速有效检测具有重要的现实意义。.以双槽电化学恒电流腐蚀法制备出孔径100-200nm、孔深10-80μm的N型多孔硅和孔径0.5-3μm，孔深2-50μm的P型多孔硅。通过溅射电极构建了2种多孔硅气敏传感器。优化后的N型和P型多孔硅气敏传感器在室温（～25°C）下对100ppb, 200ppb, 400ppb, 1000ppb NO2气体的气敏响应值分别为1.44, 1.97, 2.63, 4.25以及1.08, 1.11, 1.20, 1.28。此外，N型多孔硅具有很好的可见光增强NO2气敏性能。.采用三电极体系恒电位沉积法在N型多孔硅上生长了ZnO微/纳米颗粒，通过溅射电极构建了多孔硅基氧化锌薄膜复合材料气敏传感器。优化后的气敏传感器在最佳操作温度室温（～25°C）下对10ppb, 25ppb, 50ppb, 100ppb, 250ppb, 500ppb, 750ppb, 1000ppb NO2气体的气敏响应值分别为1.4, 1.8, 2.2, 2.6, 4.1, 5.5, 6.6和8.0，对1ppm NO2气体的响应时间和恢复时间约为58s和115s。.采用三电极体系恒电位沉积加热处理法在P型多孔硅上生长了WO3薄膜，构建了多孔硅基氧化钨薄膜复合材料气敏传感器。优化后的气敏传感器在最佳操作温度室温（～25°C）下对200ppb, 500ppb, 1000ppb, 2000ppb NO2气体的气敏响应值分别为1.67, 2.38, 2.62和2.75，对1ppm NO2气体的响应和恢复时间约为80s和105s。