利用含氟官能基對多晶矽奈米線場效電晶體表面改質之氨氣感測

Abstract

本研究針對含氟化合物修飾多晶矽奈米線場效電晶體的表面做氨氣的氣體感測，由於氟和氨氣之間會有氫鍵的產生，因此利用含氟官能基的有機材料來修飾奈米線將可以提升對於氨氣的感測能力，本實驗對兩種不同含氟官能基材料作探討，分別是F8-TFMPA跟F8-TMPEA。並利用兩種修飾方式來成長修飾層，分別是旋轉塗佈修飾法和熱蒸鍍法。另外也探討在不同的相對濕度下電晶體電性的變化。在環境濕度為40%，氨氣濃度為0.5 ppm的條件下，利用旋轉塗佈修飾的元件感測能力提升到了1.07，而利用熱蒸鍍修飾的元件則是提升到了1.30。另外熱蒸鍍修飾的材料在環境濕度為55%的條件下仍然可以達到1.14。由數據顯示出水氣和氨氣在感測過程中是互為競爭的關係。也就是當濕度愈高時，原件對於氨氣的感測能力就愈低。而F8-TMPEA這一個修飾材料對於感測能力上並無太大的提升效果。另外所有的元件都可以在低臨界電壓下操作，因此非常適合在醫學中對於患有肝病等慢性病的氨氣檢測。

This research is focused on the fluorine atoms containing organic compounds surface modified poly-Si nanowires FETs ammonia gas sensor. Due to the strong hydrogen bonding with ammonia, the sensitivity of fluorine containing organic compounds modified nanowires can be increased. Two different compounds, 1,2,3,4,5,6,7,8-Octafluoro-9,10-bis [4-(trifluoromethyl)phenyl]anthracene (F8-TFMPA) and 1,2,3,4,5,6,7,8-Octafluoro-9,10-bis[2-(2,4,6-trimethylphenyl)ethynyl]anthracene (F8-TMPEA), were investigated. The surface modified thin films were prepared by either solution or thermal deposition processes. The relative humidity was also discussed. In particular, the sensing ability of F8-TFMPA modified NWs in 40% Rh. under 0.5 ppm ammonia is increased from 1.07 (solution process) to 1.30 (thermal deposition). In addition, the sensing ability of the modified device prepared by thermal deposition can reach 1.14 at 55% Rh. The water molecular and ammonia showed competing character in the sensing results. The higher the humidity, the lower the sensitivity is. The F8-TFMPA didn’t show the strong tendency of sensitivity enhancement. All devices can be operated under low critical voltage. As a result, the device is suitable for detecting ammonia in chronic liver disease patients.