Fast response formaldehyde gas sensor for USN application

AbstractSemiconductor type gas sensors based on aluminum-doped zinc oxide with under 50nm particle size were fabricated on Si substrate. The prepared materials were very fine and uniform and we found out that particle sizes were about 10-25nm through X-ray diffraction analysis and scanning electron microscopy. Gas response characteristics were examined for formaldehyde (HCHO) gas existing in building. In particularly, the sensors showed responses to formaldehyde gas at sub ppm (cf, standard of natural environment in building is about 80 ppb), as a function of operating temperatures and gas concentrations. The lowest detection limit is HCHO 25 ppb and sensitivity of 800 ppb is over 60% at 350 oC operating temperature. The response time (8s) to HCHO gas was very fast compared to other commercial products in flow type measurement condition. Repetition measurement was very good with ±2% in full scale