Effect of carbon doping on the gas sensingcharacteristics of Ga2O3 thin film gas sensor

• Main Authors: Chia-Hao Hsu, 許嘉豪
• Other Authors: Chin-Cheng Chen
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/03130485581249907702

碩士 === 國立成功大學 === 化學工程學系碩博士班 === 97 === Because of the influence of air pollution , global warming becomes more seriously that people pay more attention to the standard of discharging gas and waste materials. Therefore gas sensors play very important role. Gallium oxide possesses the property of the semiconductor which is stable at high temperature, and has been applied in detecting reducing gas recently. In this study, C/Ga2O3 thin film gas sensor was prepared by depositing carbon thin film on a quartz substrate with plasma enhanced chemical deposition following with the deposition of gallium oxide on carbon deposited substrate by rheotaxial growth and thermal oxidation (RGTO) with water vapor. The morphology, electrical property, and element ratio of C/Ga2O3 were measured as functions of the thickness of carbon, oxidation time and the position of carbon film. The experimental results show that carbon thickness and oxidation time have no effect upon the surface morphology, but have great effect upon the diode characteristic of Ga2O3/C sample. When oxidationtime reaches 5.5 hrs, Ga2O3/C thin film shows diode characteristic in ethanol ambiance, and this characteristic makes sensitivity change with the applied voltage bias. This phenomena doesn’t exist in the junction of metal and Ga2O3 because of the work function of Ga2O3 is too high to be diode characteristic, the sample with diode characteristic can be produced with the structure of having an areal carbon film on half of Ga2O3 thin film；When carbon is deposited under Ga2O3, it acts as doping. When carbon is deposited on top of Ga2O3 film, it acts as heterojunction.