Oxygen absorption effect on the sensitivity and material stability of ZnO nanostructured films

In this work the effect of ambient influence on the electrical conductivity of ZnO films has been studied. Nanostructured ZnO films (undoped and Ga, Co, Mn doped) were exposed to oxygen (1-80 vol.%) at temperature range 300-500degC. A dominant effect of ambient influence via oxygen absorption was observed: the intensity of conductivity decrease was found to be proportional with temperature and tends to saturation with time. After oxygen saturation the reversible effect of oxygen adsorption became dominant and contributed to the films conductivity. Oxygen exposed undoped ZnO films revealed high sensitivity for oxygen content change in the ambience, therefore they have been further processed for gas sensor fabrication.