Enhancing Ammonia Sensing Ability of Poly-Si Nanowires FETs by Surface Modified Fluorine-containing Functional Groups

• Main Authors: Kuo, Wei-Ting, 郭韋廷
• Other Authors: Chen, Huang-Ming Philip
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/52428841607408243403

碩士 === 國立交通大學 === 光電工程研究所 === 103 === 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.