| Summary: | 碩士 === 國立臺灣海洋大學 === 電機工程學系 === 102 === In this thesis, a series of high-sensitive GaAs based Schottky metal-semiconductor-metal hydrogen sensors are fabricated and studied. In this thesis, a series of high-sensitive GaAs based Schottky metal-semiconductor-metal hydrogen sensors are fabricated and studied.There are two kinds of different fabrications, the first kind of hydrogen sensing metal is Palladium, and the second kind of hydrogen sensing chemistry is Silica.
In our experiment, the hydrogen sensors will put on home made variable temperature stainless steel chamber, under the fixed flow of several kinds of different concentrations H2 in N2 gas will be use.The hydrogen molecules are dissociated into hydrogen atoms when the hydrogen-containing gas adsorbs at the surface of Pd and Silica catalytic-metal. Important sensing properties such as sensing current gain, response time and recovery time were investigated by raising ambient temperature.
Furthermore, To obtain all the sensing parameters from hydrogen sensors in the variable temperature environment, the samples were systematically tested at a range of temperature from 25oC to 110oC and H2 concentration from 50ppm to 1% using an HP4145B semiconductor parameter analyzer.
The results, Sensing collector currents (ICN and ICH ) reflecting to N2 and hydrogen-containing gases are employed as output signals in common-emitter characteristics. Gummel-plot sensing characteristics with testing gases as inputs show a high sensing-collector-current gain (ICH /ICN ) of > 3000. When operating in standby mode for in situ long-term detection, power consumption is smaller than 0.4 μW. Furthermore, the room-temperature response time is 85 s for the integrated hydrogen-sensing amplifier fabricated with a bipolar-type structure.
Keywords：Schottky , Hydrogen sensor, Bipolar-type structure
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