真空蒸鍍熱氧化法製備氧化鎵薄膜氣體感測器之研究

• Main Authors: Chiu-Tsen Chen, 陳秋岑
• Other Authors: Chin-Cheng Chen
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/07548838295963689742

碩士 === 國立成功大學 === 化學工程學系 === 87 === Ga2O3 possesses an N-type semiconductor characteristic, is stable at high temperature and being applied in detecting reducing gas recently. In the present study, Ga2O3 thin film was prepared by vacuum deposition following with thermal oxidation. The effects of process conditions and Ti doping on film properties were investigated, and the multi-layer growth technique was used to control grain size. The study is aimed at investigating the processes of epitaxial growth and the influences of the composition, morphology, and structures on the properties of gas sensor. The experimental results show that Ga grain size increases as the film thickness. A 〝Buddha Head〞 type morphology appears as the thickness of film exceeds 3000A. If the oxidation is not carried out under pure O2 atmosphere, dendrites appear in the resultant Ga2O3 thin film. Corresponding to each film thickness, there is an optimum sensing temperature. At the temperature highest sensitivity and shortest response time are obtained but with a longest recovery time. Multi-layer growth technique leads to an increase of the specific surface area of thin film and avoids the growth of dendrite at thicker films, but does not improve the sensitivity. Doping Ti enhances the growth of crystalline dendrite on the resultant Ga2O3 film. At a dopant concentration of 0.28AT﹪, the sensitivity and the response time improved, but recovery time prolonged. Increasing the amount of dopant leads to more dendrites, lower sensitivity, and shorter recovery time. During the detection of ethanol, Ga2O3 film on quartz substrate has a higher sensitivity and a more stable variation of resistance than those on Al2O3 substrate. When comparing the sensitivity on detecting ethanol and CO, the Ga2O3 film shows a selectivity toward ethanol, thus more suitable for detecting ethanol. Furthermore, it has a very good reproducible resistance and sensitivity.