Abstract: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 TiO 2 , Ta 2 O 5 , and SiO 2 are deposited and characterized optically and structurally before the deposition of multilayered structures. The filter designs are based upon 33 layered SiO 2 /TiO 2 and SiO 2 /Ta 2 O 5 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). SiO 2 /Ta 2 O 5 /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. 42.79.Ci
PACS (2008):
Thin film multilayer structures based on MgF2, CeO2 and Al2O3 layers were prepared on a BK7 glass substrate with resistive heating evaporation as an antireflection coating in the 450–750 nm spectral range. Prior to deposition of the multilayer structure, individual layers of the materials used were characterized. A three-layer structure of MgF2/CeO2/Al2O3/BK7 was then prepared using the same deposition conditions as for individual layers. Reasonably low reflection was observed for the as-deposited sample with R < 0.8% from 500–750 nm and Rave < 1% over the desired spectrum. Further, low surface roughness and small particle size were seen for the as-deposited sample. Only a few low intensity peaks for the materials were observed with X-ray diffraction. Optical and structural properties were studied as a function of annealing temperature in the range 250°C–450°C. A slight shift of reflection spectra was observed with annealing, however, an increase in particle size (35 nm–70 nm) along with surface roughness was also observed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.