INFLUENCE OF ALUMINUM OXIDE SUBSTRATE SURFACE IMPURITY ON OXYGEN RESPONSE CHARACTERISTIC OF TITANIA THICK FILM

Using aluminum oxide (Al2O3) as substrate and titania (TiO2) as sensitive material, the influence of substrate surface impurity on the oxygen response characteristics of TiO2 thick film was investigated. X-ray photoelectron spectroscopy was used to inspect the impurity type (Ca, Si, Na, or N) and concentration of substrate during preparation and polishing. X-ray diffraction indicate that TiO2 thick film retaine the rutile phase with an appropriate substrate impurity. However, as the content in mole of Si was increases, there was a small area where Si and Ti ordering of the TiO2 thick film appear. Scanning electron microscope shows that the higher the concentration of Ca and Na, the larger the grain of the material became under a surface cladding. The voltammetric testing shows that the higher the Ca concentration, the more holes appeared in the deep level defects, and the oxygen characteristics at high temperature are worse. The results indicate that the vacancy of Ti created by Ca, Si and Na staying on the substrate is the main factor that influences the response characteristics and response time of TiO2 thick film at high temperature.