雙爐管式氣液固相變化機製成長氧化鋅奈米線及其氣體感測特性之研究

Abstract

本研究主要是使用double-tube的方式藉由VLS (Vapor-Liquid-Solid)技術，不需要利用金(Au)觸媒做為催化劑或模板，直接將氧化鋅( Zinc Oxide )奈米線( nanowires )成功的生成於玻璃基板上。結果顯示，工作溫度900◦C，可成功的控制氧化鋅奈米結構成長。此外，改變氧氣流量會對成長氧化鋅奈米線之緻密性與長度有影響，經XRD分析發現，氧化鋅奈米線隨通入氧氣增加繞射峰值也越強，並且呈現(002)為優選成長方向。 以SEM表面組織型態來觀察，當通入8 sccm之氧氣流量的條件下，Al/glass 基板上成長出高深寬比氧化鋅奈米線，奈米線結構緻密性也有提升。在8 sccm之氧化鋅奈米線試片，對於I-V量測也有明顯的電傳導特性，而氣體感測結果發現，奈米線結構對NO2氣體比CO氣體有較佳的感測特性，其響應時間與回復時間都較短，對長期的再現性與穩定性之維持良好。在感測環境工作溫度175◦C，偵測NO2 濃度20 ppm、60 ppm、100 ppm所得最佳感測靈敏度分別為23、33、41。

This study is aiming on demonstrating Zinc Oxide (ZnO) nanostructures were successfully grown on Al/glass substrates by using a double-tube vapor-liquid-solid (VLS) technique without any gold (Au) metal catalyst or template. When the temperature was set at 900◦C, ZnO nanostructures were grown successfully under controlled. With the XRD analysis, ZnO nanowires were preferably grown in (002) direction and were in direct ration to the oxygen level. Also, the result of this study showed that the ratio of oxygen gas flow has the impact of the length and density of ZnO nanowires. ZnO nanowires were grown on Al/glass substrates in high density with 8 sccm oxygen gas flow under observing by Scanning Electron Microscope (SEM). It is also found that the ZnO nanowire 8 sccm sample has an outstanding electrical conduction property to measure the I-V characteristics. Moreover, ZnO nanowire has a better sensitivity to NO2 in compare of CO. Its response and recovery time are shorter with an excellent long-term reproducibility and stability. The sensitivities are 23、33、41 when it is to detect NO2 at 20 ppm, 60 ppm, 100 ppm, respectively, at 175◦C.