The formation of diffraction gratings by the deposition of SiO2 colloidal microspheres

A simple way of fabrication of diffraction gratings with the help of deposition of SiO2 colloidal particles on vertical glass substrate has been proposed. The method is based on an intermittent, “stick–slip” motion of the suspension meniscus during liquid evaporation. The deposition was carried out at different temperatures (from 27 to 50 °C). Ethanol-based suspensions with a SiO2 concentration in the range of 0.2–0.83 g/L, both narrow-dispersed with SiO2 particle diameter of about 200–300 nm and polydisperse, were used. As a result, the structures consisting of parallel ridges of deposited SiO2 microspheres repeating with a period of 140–200 μm and empty gaps between them have been prepared. The diffraction gratings formation is possible only at temperatures higher than the critical value of about 30 °C, and their period enhances with the temperature increase. The real diffraction patterns of light have been obtained for such structures for the first time. Further modification of prepared structures with the purpose of their strengthening has been realized with the help of high-dose Ag+ implantation (4 × 1016 ions/cm2, ion energy of 30 keV) followed by sonication.