Coatings with a High Surface Roughness Prepared by a Co-sputtering Method Using Dual Rotatable Magnetrons

A new method for the deposition of rough thin filmswas developed. Therefore a gradient film of twodifferent materials was prepared by a co sputteringmethod using a dual rotatable magnetron system.After the film deposition one of the layer componentshas been removed by a (wet) etching process.In result a rough thin film was produced.For the demonstration of this new technique arough silica (SiO2) film was chosen. Due to itssurface roughness the resulting refractive index gota gradient from air to solid silica. Accordingly thefilm structure got antireflective properties. Films witha reflectance decrease up to 3 %, a simultaneoustransmittance increase of 2 to 3 % and a maximumroughness Rt of 60 nm were obtained.