提升多晶矽奈米線場效電晶體對氨之靈敏度

Abstract

本研究利用多晶矽奈米線場效電晶體作一個無需標記並可即時監測的氨氣檢測器。一般多晶矽奈米線場效電晶體在低氨濃度的環境下的感測能力有限，且對極小氨氣濃度變化的鑑別度低。為了解決此議題，多晶矽奈米線場效電晶體的表面利用紫外光-臭氧照射以及寡聚物的表面處理來改善其感測能力。研究結果發現，照射過紫外光/臭氧的多晶矽奈米線場效電晶體操作在室溫及0.5 ppm氨氣環境下，其氨氣對氮氣的電流比值大約是180，為沒有照射紫外光/臭氧之元件的一百倍；經寡聚物表面處理之元件的電流比值則有26，相較於沒有表面改質的元件改善了十倍。除此之外，當氨氣濃度從0.25 ppm變化到0.5 ppm再到0.75 ppm，此時照射過紫外光/臭氧之元件的電流比值也會從約96變化到180再到400。這三個不同的電流比值展現出經過紫外光/臭氧照射的多晶矽奈米線場效電晶體具有小濃度變化的鑑別度。

In this study, the poly-silicon nanowire field effect transistor (poly-Si NW FET) was applied as a gas sensor for label-free and real-time detection of ammonia gas. The sensing ability of poly-Si NW FET as a NH3 gas sensor is limited by the low gas concentration and its distinguishability. To address these issues, the surface of poly-silicon nanowire was modified by the UV-ozone irradiation and oligomer functionalization. For detecting 0.5 ppm NH3 gas, an ultra-high NH3/N2 current ratio of 180 was obtained by the UV-ozone irradiated poly-Si NW FET, the magnitude was 2 orders higher than the device without treatment at room temperature. The oligomer functionalized poly-Si NW FET exhibits a high NH3/N2 current ratio of 26, which is one order higher than the device without treatment. In addition, the NH3/N2 current ratio of the UV-ozone irradiated device was varied from 96 to 180 and 400 when concentration of NH3 gas was increased from 0.25 to 0.50 and 0.75 ppm, respectively. Based on the concentration sensitive results, the UV-ozone irradiated poly-Si NW FET improved the distinguishability for the NH3 detection.