Sensing characteristics of ZnO-based NOx sensor

Sensing characteristics of ZnO-based sputtered films are studied. The film about 140 nm thick showed high sensitivity to NOx and selectivity against H -2 and CO. The sputtering pressure greatly affected the sensitivity, and th e sensitivity maximum was observed at 0.67 Pa. The effect of element doping into ZnO on sensitivity and selectivity to NOx was also studied using co-s puttering technique. Rare earth element doping improved sensitivity and sel ectivity to NOx against NO. Er-doped ZnO film had good selectivity and fast response time to NO2 above 200 degrees C, and almost linear sensitivity de pendence in the sub-ppm concentration range of NO2. (C) 2000 Elsevier Scien ce S.A. All rights reserved.