SPECIFIC PALLADIUM AND PLATINUM DOPING FOR SNO2-BASED THIN-FILM SENSOR ARRAYS

Undoped, Pd- and Pt-doped SnO2-based thin film chemical sensors. have been developed. The distribution of metallic dopant atoms and ions at the surface and at bulk positions of the SnO2 lattice was adjusted during the preparation and subsequent temperature treatments at constant oxygen partial pressure. The sensitivities and selectivities of these SnO2 thin film conductance sensors to detect small concentrations of NO2, CH4, CO and H2 in air were characterized. The different contributions from contacts, surface, bulk and grain boundaries to the sensor response were separated with two-, three- and four-point d.c. and a.c. measurements using different electrode configurations. Finally, we evaluated responses from sensor arrays to CO/NO2 and CO/CH4 mixtures with PCA (principal component analysis), PLS (partial least squares) and PCR (principal component regression) to analyse these mixtures quantitatively.