Gb. Barbi et al., ULTRAFINE GRAIN-SIZE TIN-OXIDE FILMS FOR CARBON-MONOXIDE MONITORING IN URBAN ENVIRONMENTS, Sensors and actuators. B, Chemical, 25(1-3), 1995, pp. 559-563
Various types of ultrafine grain-size SnO2 sensors have been fabricate
d using a reactive sputtering technique. Some have been doped using tw
o different techniques: deposition (by sputtering) of a thin layer of
platinum or platinum implantation. The samples are characterized using
ellipsometry, ESCA/Auger spectroscopy, glancing angle XRD and RES. Se
nsor sensitivity measurements are carried out in the CO concentration
range 5-100 ppm in dry air between 100 and 350 degrees C. For non-dope
d samples, the sensitivity is found to increase with temperature. The
results obtained with the Pt-implanted sensors are variable and merit
further investigation. The effects of the presence of low concentratio
ns of NO2 in NO2/CO atmospheres have also been analyzed. It can be sho
wn that a selective response to NO2 and CO/air mixtures can be achieve
d by a suitable choice of the sensor operating temperature.