Optical investigation of sol–gel-synthesized and spin-coated SiO2/TiO2 multilayers

Abstract

In this work, silicon dioxide (SiO2)/titanium dioxide (TiO2) multilayer films were deposited on silicon substrates through the sol–gel spin-coating technique using the precursors titanium butoxide and tetraethyl orthosilicate. After the preparation, the various optical and morphological properties of the films were studied by using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and ultraviolet–visible (UV–Vis) spectroscopy. The XRD patterns showed intense diffraction peaks, which were found to correspond to anatase titanium dioxide and it matched well the standard Joint Committee on Powder Diffraction Standards file. The crystallite sizes of the prepared samples were calculated as 24 nm for three stacks of silicon dioxide/titanium dioxide thin films and 30 nm for five stacks of silicon dioxide/titanium dioxide thin films using Debye–Scherrer’s formula. The FTIR transmittance spectra confirmed Si–O–Ti vibrational modes at 800 and 960 cm−1 with related functional groups. A reflectance of 86% was measured by using UV–Vis spectroscopy. These dielectric multipliers will be useful in solar cells as backside reflectors for an improved light-harvesting mechanism.