Abstract
This paper presents the results of investigations of optical scattering phenomena in porous silica films. SiO2 films were prepared by the sol-gel method and deposited on polished silicon wafers by the dip-coating technique. Fabricated films were studied using integrating sphere reflectometry, spectroscopic ellipsometry, atomic force microscopy, scanning electron microscopy, and angular resolve scattering. The spectral characteristics of the refractive and extinction indices and scattering extinction coefficients are presented. Additionally, the depolarization of reflected beam from samples was measured. The tested films were characterized by a thickness of 500 to 900 nm, a porosity of 50%, and refractive indices of less than 1.24. The observed depolarization of light reflected from SiO2 films resulted from surface and bulk scattering. This phenomenon resulted from the presence of surface and closed pores located in the bulk of SiO2 film.
Highlights
This paper presents the optical properties of silica films of low refractive index obtained by sol-gel technology
Porous silica films find applications in important areas, such as photonics and optoelectronics. Due to their low refractive index, silica films can be applied in optical systems to reduce light reflectance [5]
In the research presented here, the starting solutions were prepared with the application of the following solutions: Tetraethyl orthosilicate (TEOS), purity 99.0%, supplied by Sigma-Aldrich, Poznan, Poland; water; absolute ethanol C2 H5 OH (EtOH), 99.8%, supplied by Avantor Performance Materials, Gliwice, Poland; and hydrochloric acid, 37%, supplied by Avantor Avantor Performance Materials, Gliwice, Poland and used as a catalyst
Summary
This paper presents the optical properties of silica films of low refractive index obtained by sol-gel technology. Such fabricated SiO2 films can exhibit a porous structure [1]. Porous silica films find applications in important areas, such as photonics and optoelectronics Due to their low refractive index, silica films can be applied in optical systems to reduce light reflectance [5]. It allows regarding porous SiO2 films as a very good material for the production of antireflective coatings (ARC) for glasses [6,7,8]. Materials can possess a compact or a porous structure, in which pore size can vary from a few to dozens of nanometers
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