| Summary: | 碩士 === 國立成功大學 === 微電子工程研究所碩博士班 === 91 === Many types of hydrogen sensors have been investigated and studied comprehensively in several decades. Among them, the semiconductor type hydrogen sensors have attracted great attention due to the advantages of high hydrogen detection sensitivity, low cost and matured techniques. Three hydrogen sensors based on AlGaAs material were fabricated and studied systematically in this thesis. The transient response and hydrogen detection sensitivity of the studied devices under different hydrogen concentrations, temperature and applied voltages were measured. In addition, the kinetic and thermodynamic properties of hydrogen adsorption were discussed.
The Metal-Oxide-Semiconductor (MOS) Schottky-barrier diode hydrogen sensor based on Pd catalytic metal and Al0.3Ga0.7As material were studied in chapter 2. The studied device exhibits excellent diode characteristic including low reverse saturation current and high operating temperature. Comparing to the InP and GaAs based devices, the studied device demonstrated higher operation temperature regime while keeping high hydrogen detection sensitivity.
The influence of oxide layer on hydrogen detection ability has been studied. It has been observed that the oxide can restrain the Fermi-level pinning effect effectively by preventing the reaction of Pd catalytic metal and AlGaAs material.
The influence of different catalytic metals has been studied, too. Except the Pd metal, the Pt also shows high sensitivity and selectivity to hydrogen gas. A Pt/oxide /Al0.3Ga0.7As metal-oxide-semiconductor (MOS) Schottky diode hydrogen sensor was fabricated. The hydrogen detection performance, thermodynamic property was studied.
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