DEPENDENCE OF SENSITIVITY OF SNOX THIN-FILM GAS SENSORS ON VACANCY DEFECTS

Oxygen flow during dc reactive sputtering of SnOx thin films affects f ilm conductivity in zero grade air and gas sensitivity to carbon monox ide and ethanol. The experimental results show that an increase in oxy gen flow during film deposition produces films exhibiting higher condu ctivity in zero grade air and lower gas sensitivity. A theoretical mod el is presented that explains this behavior. The proposed model takes into account both the dependence of conductivity on the potential barr ier height at grain boundaries of the film and the dependence of chemi sorption rate of oxygen on free-electron availability. The theoretical analysis is in good qualitative agreement with experiment. (C) 1996 A merican Institute of Physics.