Complex multilayer thin film filters for optical applications have been designed, prepared and characterized in this work. E-beam reactive evaporation technique has been used as a deposition process. In the first stage, optimized individual film layers of TiO2, Ta2O5, and SiO2 are deposited and characterized optically and structurally before the deposition of multilayered structures. The filter designs are based upon 33 layered SiO2/TiO2 and SiO2/Ta2O5 configurations on glass substrate. These designs are optimized to achieve wideband transmission in the visible spectrum. After deposition, the two filter configurations are characterized optically and structurally using spectrophotometery, atomic force microscopy (AFM), X-ray diffraction (XRD) and scanning electron microscopy (SEM). SiO2/Ta2O5/glass filter has been found sensitive to deposition conditions since high absorption is observed in multilayered configuration for the as-deposited samples. Post-deposition annealing of the filter in the temperature range 150 to 250°C was also performed in order to study the effect of temperature on absorption and spectral characteristics of the filter. Comparison of the two filter configurations was also performed to analyze their suitability for optical applications. Adhesion of the two filters was found to be very good by means of tape-peel test.
Financed by the National Centre for Research and Development under grant No. SP/I/1/77065/10 by the strategic scientific research and experimental development program:
SYNAT - “Interdisciplinary System for Interactive Scientific and Scientific-Technical Information”.