Thermoelectric hydrogen sensors using Si and SiGe thin films with a catalytic combustor

Micro-machined thermoelectric hydrogen sensors (micro-THS) with catalyst combustors were fabricated using Si and SiGe thin films prepared using the sputtering or chemical vapor deposition methods, and the relationship between the thermoelectric property of the films and the performance of the sensors were investigated. The Seebeck coefficients of the Si and SiGe films were evaluated as 107-246 and 82-126 uμV/K at temperatures of 50-480°C. The combustion heat estimated by increasing the temperature of the catalyst on the micro-THS with the Si thin film was 7-20% smaller than that of SiGe thin film. Moreover, the voltage signal of the micro-THS with the Si thin film was 8-13% larger than that of SiGe thin film. Both the Seebeck coefficient of the Si thin films and the voltage signal of the micro-THSs with the Si TE films were better than those of the SiGe thin film, although the combustion heat of the catalyst on the micro-THSs with the Si thin films was smaller compared to that with the SiGe thin film. For the micro sensor application using the thermoelectric thin film, the Seebeck coefficient is the most important factor to improve the sensor performance.