The Effect of Annealing Duration Accumulation on Structural and Optical Properties of SiO2/TiO2multibilayers Processed by the Sol-Gelmethod

SiO2/TiO2 multibilayers were developed on glass substrates and silicon wafers by the sol-gel method. Dip-coated layers were characterized by different experimental techniques: XRD, Raman, SIMS, FTIR, UV-Vis and photoluminescence. The obtained XRD patterns and Raman spectra, for various annealing duration accumulation,are in good agreement and have shown that the films crystallize in anatase phase.As this duration increases DRX and Raman grain size decreases from12.33 nmto 8.86 nmand from 17.01 to 16.94 nm, respectively. FTIR spectra have shown that Si-O-Ti bands vibration is intensified by increasing annealing duration. SIMS analysis shows an interdiffusion zone at the first bilayer allowing the formation of the SiO2-TiO2 structure, thus confirming the results obtained by FTIR. Increasing the latter shows also that resulted films are transparent to the visible range and opaque in the ultraviolet region. Optical band gap energy and photoluminescence (PL) intensity have decreased upon the increase in the annealing duration accumulation.