Improved Response Time of Al–Al2O3–Pd Tunnel Diode Hydrogen Gas Sensor

An Al–Al2O3–Pd tunnel diode acts as a sensitive hydrogen gas sensor. A serious drawback, however, of this hydrogen gas sensor operating at room temperature was a very long response time, typically 30 min. To overcome this disadvantage, the Pd tunnel diode was operated at elevated temperatures, resulting in a marked reduction of the response time, less than 1 min at 83°C. A microheater attached to the back surface of the substrate could be an efficient power source to heat the hydrogen sensor to the required temperature.