探討不同相對濕度環境下含聯三伸苯結構之有機材料於多晶矽奈米線場效電晶體表面修飾對氨氣感測影響

Abstract

本研究探討以兩種含triphenylene結構的盤狀液晶材料當作多晶矽奈米線電晶體的表面修飾層，觀察修飾後的元件對氨氣感測的影響，並針對不同的修飾方法，腔體內的水氣含量及修飾層的表面形態等條件進行討論。實驗中利用兩種不同的修飾方法：真空蒸鍍和旋塗，將cchxnTP和HAT5沉積於奈米線表面，實驗結果顯示，兩種不同的修飾方式和材料皆造成電晶體的汲極電流隨著通入腔體內的氨氣濃度上升而上升。此外，在較高相對濕度的環境下，元件對氨氣的感測能力皆會下降。修飾層不同的表面型態也會對氨氣感測造成影響：以旋塗佈方飾修飾的元件因表面修飾層的結構較為鬆散，使腔體內的氨氣分子與其它帶電的離子更容易藉由擴散的方式進入奈米線通道，改變奈米線電晶體的導電率達到感測目的。這些結果顯示，不同的修飾方式、水氣含量和修飾層的表面形態皆會影響多晶矽奈米線電晶體的感測特性。

The objective of this study is to investigate how surface modification layers affect gas sensing characteristics in ambient environment. In this study, the influences of different modification methods, moisture levels and surface morphologies on ammonia sensing characteristics in poly-Si NW FETs are discussed. By modifying the surface of poly-Si nanowires with cchxnTP and HAT5 through thermal evaporation and spin-coating methods, we found that both modification methods resulted in higher drain current as the concentration of ammonia gas increased. Regardless of different modification methods, the detection ability of NW FETs decreased at higher moisture levels. Different surface morphology also resulted in different detection ability. More specifically, loose-packing films produced by spin-coating were more likely to allow ammonia gas to diffuse into the NW channel, which caused a greater change in drain current. These results indicate that modification methods, moisture levels and surface morphology could affect the sensing characteristics of poly-Si NW FETs.