【作者】 吴嘉浩；

【导师】 张亚非；

【作者基本信息】 上海交通大学 ， 微电子学与固体电子学， 2008， 硕士

【摘要】 气体离化传感器通过加局部高电场,使待测气体电离、发生放电来进行对气体的检测。不同的气体具有不同的击穿电压。利用这一指纹特性,电离式气体传感器可以识别气体的种类。与吸附式传感器相比,离化式传感器不受被测气体化学吸附性的影响,并且具有灵敏度高,响应速度快,恢复时间短的优势。本文提出了一种将MEMS加工方法与碳纳米管薄膜沉积相集成的、基于电离原理的微气体传感器:1)应用了气体电离检测方法,不再受被测气体化学吸附性的影响,具有灵敏度高,响应速度快,恢复时间短的优势;2)应用了碳纳米管作为电极功能材料,发挥了碳纳米管的一维结构、场发射性能和负电子亲合势等优越性,进一步增强了离化电场,降低了器件的工作电压3)在离化器件中引入了介电阻挡层(DBD)结构,对击穿时电荷的增长、放电电流的突变进行了有效的控制,减小了气体击穿对器件寿命的影响4)总结了一套使用电泳电镀相结合的方法沉积镍-碳纳米管复合薄膜的方法,作为的制备和研究此传感器的基础。与丝网印刷、混合电镀、电泳等方法相比,镍-碳纳米管复合薄膜密度可控、排布均匀、表面平整,并且具有较小的表面电阻、较好的场发射性能,更易与MEMS加工方法结合;5)设计并加工实现了两种微电极系统电离式气体传感器。综合了MEMS加工方法和碳纳米管复合薄膜沉积方法,大幅减小了器件结构中阴阳两极间距,增强了离化电场,使空气等8种气体的击穿电压降至36V以下,成功在低于人体工程学安全电压的条件下,应用气体击穿电压的指纹特性,对8种气体进行了识别;同时对离化传感器对呼吸和对有机混合气体敏感的特性和也作了研究。更多还原

【Abstract】 Ionization gas sensors are working on ionization of gas molecular since the partial strong electrical field. Based on the breakdown voltage’s finger print character, each gas can be identified by its unique ionization or breakdown voltage. Ionization gas sensors have much shorter response time, better sensitivity, and shorter recovering time than the normal absorption sensors.We have demonstrated here a MEMS based ionization micro gas sensor with these works:1) The sensor is working on the ionization principle, which means it would not be affected by the affinity energy and chemistry absorption properties of gases; on the contrary, it would be equipped with shorter response time, better sensitivity, and shorter recovering time;2) We have used CNT (Carbon Nanotubes) as the functional material in the electrodes, there would be greater electrical field and lower working voltage because of the one-dimensional structure and negative electron affinity of CNT;3) DBD (dielectric barrier discharge) principle has been introduced to the device, experiments results prove that it could increase electrical field and reduce the working voltage;4) We have concluded a method of deposition Nickel-coated-CNTF (Carbon Nanotube Film) as the fundamental of fabrication of CNT based ionization device. Experiments results prove that the Nickel-coated-CNTF has flat surface, controllable density, uniform arrangement, better performance of field emission, and could be integrated with MEMS processes easier.5) We have designed and fabricated two structures of micro electrode device. The advantage of using MEMS processes and Nickel-coated-CNTF deposition method ensures the device has shorter distance between the electrodes and higher electrical field, which makes it’s possible to ionization 8 gases under a working voltage less than 36V. Based on this fingerprint principle, the device could successfully identify these 8 different gases. Besides that, we also concentrate on the property of the response on human breath and on mixed organic gases.更多还原