Abstract
Improvement of the response time by direct heating of the gate catalytic metal of an FET sensor was investigated. The FET hydrogen sensor that has an adhesion layer (Ti) between the catalytic metal (Pt) and the gate insulator was fabricated. In a previous study, there was a problem in the reproducibility as some of the FET sensors displayed long recovery characteristics caused by hydrogen atoms diffused into the Pt thin film. To improve the response characteristics, two electrodes were connected to the gate metal, then, a pulse current was applied to the gate metal, having a resistance element. When applying the pulse current to the gate portion, desorption of the hydrogen remaining in the platinum thin film was accelerated because the platinum was instantaneously heated. Consequently, the hysteresis of the hydrogen was improved. Furthermore, reproducible response, fast response time and recovery time were achieved.
