Performance of silicon carbide high temperature gas sensors

Silicon carbide based devices are well suited for high temperatures applications such as gas sensors and electronic circuits for control and emissions applications in automobiles and power plants. We have developed a high sensitivity Pt-SiO₂-SiC solid-state hydrogen gas sensor. The response time of this metal-oxide-semiconductor field-effect device to hydrogen-containing species at 600degC is in the millisecond regime. In good agreement with standard models, the sensor response to hydrogen concentration is logarithmic over at least four decades of concentration. Based on a detailed understanding of the hydrogen transduction mechanisms, we have determined the optimum sensor biasing conditions for reliable high temperature operation. We report on the measurement accuracy and stability for a sensor that has run for 18 continues days with negligible degradation in performance at 600degC