Gas sensing characteristics of low-powered dual MOSFET hydrogen sensors

Abstract A low-powered hydrogen sensitive dual-MOSFET device was designed, fabricated and evaluated for its ability to self compensate for electric signal degradation. The differential outputs between the sensing- and reference-FET were preserved within 3.74 μA to the thermal change (from 50 °C to 150 °C) due to the same dependence of the electrical characteristics. The proposed sensor design showed low power consumption (45.5 mW at 150 °C) by achieving complete heat isolation. Stable responses to H 2 gas were observed over wide temperature ranges and the optimal point in the micro-heater operation was approximately 150 °C. (The highest sensitivity to 5000 ppm H 2 gas was 111.17 μA with response and recovery times of 18 s and 19 s, respectively.) From the experimental results, the increased sensitivity to various H 2 concentrations corresponded to the Langmuir relationship. The fabricated sensor device showed good gas selectivity toward CO and NH 3 gases, and it showed a good performance in the facet of reproducible responses.