THERMAL-STABILITY OF PYROLYTIC TIN OXIDE-FILMS ON ALUMINUM

The optical properties of tin oxide-coated aluminium and anodized alum inium are reported. It is shown that after annealing the coating on ba re aluminium becomes highly absorbing while the coating on anodized al uminium is stable at 480 degrees C and does not change. Optical modell ing and Auger electron spectroscopy are used to explore the possible r eason behind this behaviour. It is suggested that the most feasible ex planation is an interfacial reaction between the metal and the oxide. Optical constants for a mixture of aluminium and tin oxide calculated according to the Bruggeman effective medium theory are presented, toge ther with calculated reflectance spectra that fit the experimental spe ctra. The results demonstrate the high sensitivity of optical spectros copy for the analysis of coated surfaces.