【作者】 冯有才；

【导师】 胡明；

【作者基本信息】 天津大学 ， 微电子学与固体电子学， 2007， 硕士

【摘要】 在工业生产和日常生活中,人们已经广泛使用气敏元件对毒性气体和易燃易爆性气体进行检测,以确保生产和生命的安全。因而对气体传感器的要求也越来越高,这势必推动了高灵敏度、高可靠性、高选择性气敏传感器的研制。在众多的气敏材料中,WO3以其优异的气敏特性和高稳定性脱颖而出。三氧化钨是一种n型半导体材料,当它暴露于被测气体(NOx、H2、CO、NH3、C2H5OH等)中时,从空气中吸附的氧作为一种电子的受主态处于三氧化钨材料的禁带,气体在其表面的反应导致了受主态在部分表面覆盖度的变化,从而引起了电导率的变化。目前三氧化钨薄膜气敏传感器的研究方兴未艾,研究人员广泛采用溶胶凝胶法、真空蒸发法来制备的三氧化钨气敏薄膜。考虑到溅射法具有薄膜纯度高,膜与基底之间附着性好,构成薄膜的微粒粒径较均匀,容易实现纳米微粒薄膜,工艺条件容易控制等优点,本论文利用对向靶直流反应磁控溅射来制备具有高灵敏度的WO3气敏薄膜。通过设计不同的实验,借助SEM、AFM、XRD等先进的分析工具以及自主搭建的静态配气测试系统研究探讨了基片材料、溅射过程中基片温度、溅射气体比例、热处理等工艺条件对样品的微观结构、电学和气敏性能的影响,发现了部分影响规律和部分条件的最佳工艺参数。用表面改性方法使气敏薄膜的灵敏度、工作温度、选择性及反应速率等方面均得到不同程度的提高和改善。添加Ti后,当表面改性层TiO2的膜厚为30nm时,薄膜的微观结构得到很大的改善,在体积分数为15×10-6的NO2中,当工作温度为120℃时,灵敏度达到25.2,并且具有良好的选择性和较短的响应时间,是一种理想的NO2气敏传感器。更多还原

【Abstract】 In industrial production and daily life, gas sensors has been widely used to detect toxic gases, flammable gases, and explosive gases to ensure the security of production and life. Therefore the increasingly highly requirements for gas sensors will promote a highly sensitive, reliable, selective gas sensor development. In many gas-sensing materials, WO3 gas comes to the fore because of its excellent gas-sensitivity and highly stability. Tungsten trioxide is one n-type semiconductor material,when it is exposed to the gas which is to be detected (NOx, H2, CO, NH3, C2H5OH, etc.), oxygen adsorbed from the air as an electron acceptor state is in three tungsten oxide material’s cut-belt, the reaction of gas on the surface caused that the coverage on some parts of the surface changes, which led to a conductivity change. Currently study of WO3 thin film sensor is just in the ascendant, researchers widely used sol-gel method and vacuum evaporation method to make the gas-sensitive tungsten oxide films.Taking into account that sputtering films have highly purity, good adhesion between film and substrate, uniform-sized particle which constitutes the film, easy realization of nanoparticle films, and that the process is easier to control and so on, in this thesis, facing targets direct current magnetron sputtering method is used to prepare WO3 thin films with highly gas-sensing. Via designing of different experiments, this thesis uses SEM, AFM, XRD and other advanced analytical tools and static gas testing system to analyze the influence of the substrate material, the substrate temperature and sputtering gas ratio, annealing conditions to the microscopic structure, electricity and gas properties of the sample, and found some rules and optimal parameters of some conditions.The sensitivity, operating temperature, selectivity and response time of the superficial modified WO3 thin films have been improved with varying degree. After appending Ti, when the thickness of superficial modified TiO2 layer is 30nm, the microstructure of WO3 thin film has been obviously improved, in the case of operating temperature for 120℃and 15ppm NO2 , the sensitivity achieves 25.2, and WO3 film has the good selectivity and the shorter response time, and is one kind of ideal gas sensor.更多还原