| Summary: | 碩士 === 大同工學院 === 電機工程研究所 === 87 === Zinc Oxide, which has strong piezoelectric effect and can be sputtered on a variety of substrates, is a natural choice as the piezoelectric film layer in recent years. The Corning 7059 glass substrate, whose thermal expansion coefficient is nearly equal to that of ZnO single crystal, is usually chosen as the substrate for ZnO thin film.
Reliable gas and humidity detectors are becoming of great importance in environment control. A variety of materials have been used for gas and humidity sensing based on its conductivity changes produced by the oxidation and reduction of adsorbed gas. Tin Oxide (SnO2), one of these semi-conducting materials, is very widely used for sensing oxidizing/reducing gases due to its high sensitivity to small concentrations of gas (at p.p.m. level).
The goal of this preliminary research is to obtain high quality and preferred-oriented SnO2 and ZnO films by RF magnetron sputtering for their humidity sensing applications. Firstly, we deposit the ZnO film on Corning 7059 glass substrate by RF magnetron sputtering. Secondly, we use the photolithographic and the lift-off process to fabricate the inter-digital transducer (IDT) on this piezoelectric layer and get a ZnO film SAW delay line structure. Thirdly, we deposit a thin layer of SnO2 on the ZnO film SAW delay line. Finally, we will measure this SAW humidity sensor, and discuss its sensitivity, response time, etc.
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