Optical anisotropy of glancing angle deposited thin films on nano-patterned substrates

This study has demonstrated that 3D columnar micro-films/coatings can be deposited over pre-patterned surfaces with sub-micrometer periodic patterns. Four-angle polarisation analysis of thin (0.4-1-mu m) Si and SiO2 films, evaporated via glancing angle deposition (GLAD) at 70 degrees to the normal, was carried out in reflection mode using synchrotron infrared microspectroscopy at the Australian Synchrotron. The angular dependence of absorbance followed A(theta) proportional to cos(2)theta, confirmed for Si substrates patterned by electron beam lithography and plasma etching, which were used to make checkerboard patterns of Lambda = 0.4 similar to mu m period on Si. Retardance control by birefringence of a patterned SiO2 substrate coated by columnar SiO2 is promising for UV-visible applications due to the use of the same material to endow polarisation control. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement