表面修飾多晶矽奈米線場效電晶體對於氨氣及一氧化氮的感測選擇性

Abstract

本研究探討多晶矽奈米線場效電晶體於不同水氣環境下對低濃度氨氣和一氧化氮的感測能力，由於氨氣及一氧化氮氣體在電子的轉移中具有相反的特性，對元件的電性曲線會產生相異的影響，進而達到兩種氣體的感測選擇性。實驗中分別利用四種抗氧化劑材料以熱蒸鍍的方式對奈米線場效電晶體進行表面修飾，憑藉材料傾向失去電子的特性，強化元件和氨氣及一氧化氮分子的反應，進而提升元件的感測能力。最後，實驗結果顯示抗氧化劑材料修飾層皆有助於提升元件對於氨氣及一氧化氮的感測能力，其中效果最顯著之材料為S-Hexylglutathione，在相對溼度40%的環境下，對於0.5 ppm之氨氣感測靈敏度由2%上升至54%，對於10 ppb之一氧化氮感測靈敏度由9%上升至19%，因此非常適合用於生醫領域中患有肝病及氣喘的相關疾病檢測。

In the thesis, we discussed the sensitivity of poly-Si nanowires field effect transistors (p-Si NWs FETs) towards low-concentration ammonia gas and nitric oxide gas under different relative humidity. Due to different properties of nitric oxide and ammonia molecules, the device showed opposite current ratio results towards them. Therefore, it could reach the selectivity of ammonia and nitric oxide gas sensitivity. Moreover, in order to enhance the sensing ability, four antioxidants were selected as chemical modification layer on the NW surface. Antioxidants are prone to lose electrons which will strengthen the interaction between the NWs surface and the two kinds of gas and further promote the sensing ability. In conclusion, the experimental results showed that certain antioxidant increased approximately 52% sensing ability at 0.5 ppm ammonia gas; and presented 10% gas sensing ability at 10 ppb at nitric oxide gas under 40% humidity. Therefore, the modified p-Si NWs FETs are suitable for biomedical detection application of liver or asthma diseases.