Engineering Commons^™

Micro-Fabricated Hydrogen Sensors Operating At Elevated Temperatures, Chi Lu

University of Kentucky Doctoral Dissertations

In this dissertation, three types of microfabricated solid-state sensors had been designed and developed on silicon wafers, aiming to detect hydrogen gas at elevated temperatures. Based on the material properties and sensing mechanisms, they were operated at 140°C, 500°C, and 300°C. The MOS-capacitor device working at 140°C utilized nickel instead of the widely-used expensive palladium, and the performance remained excellent. For very-high temperature sensing (500°C), the conductivity of the thermally oxidized TiO₂ thin film based on the anodic aluminum oxide (AAO) substrate changed 25 times in response to 5 ppm H₂ and the response transient times were just …