RECOGNITION OF HYDROGEN AND AMMONIA BY MODIFIED GATE METALLIZATION OF THE SUSPENDED-GATE FET

Suspended-gate field-effect transistors (SGFETs) are investigated for a possible independent detection of hydrogen and ammonia in synthetic air. The suspended gate is modified by electrochemical deposition in order to obtain Pd and SnOx active layers. For SnOx-coated SGFETs, a sensitivity to NH3 even at room temperature is observed without any response to H2. The Pd system is stable at temperatures above 140°C and sensitive to H2 as well as NH3. The combination of both sensors allows the two gaseous species to be recognized independently. © 1990.