A novel gate-structure FET-type hydrogen sensor (Pt/Ti-FET) thathas an adhesion layer (Ti) between the catalytic metal (Pt) and the gate insulator was fabricated. The dependence of the response characteristics of the sensitivity and selectivity on the Ti thickness was investigated. The sensitivity showed dependence on Ti thickness, and higher sensitivity was obtained with a decrement in Ti thickness. In addition, the Pt/Ti-FET showed good selectivity against other gases (02, C2H6) compared with the Pt-FET. After annealing at 260°C for 30 min under 5 Pa in a vacuum, the Pt/Ti-FET showed different response characteristics from an as-depositedPt/Ti- FET. The annealed Pt/Ti-FETs with a thin Ti adhesion layer (below 10 nm) showed improved hydrogen sensitivity. In particular, the Ti5-nm sample of the Pt/Ti-FET sensor showed a higher hydrogen responsewhen exposed to 0.8% hydrogen gas (526.2 mV) compared to that of the Pt-FET sensor (415.7 mV). However, improvement in hydrogen sensitivity was not obtained in thick Ti samples. Additionally the annealed Pt/Ti-FET showed better selectivity against 0 2 than as-deposited Pt/Ti-FET.
- Chemical sensors
- Field effect transistor (FET)
- Hydrogen sensor
ASJC Scopus subject areas
- Electrical and Electronic Engineering
- Mechanical Engineering