A Model Surface for Calculating the Reflectance of Smooth and Rough Aluminum Layers in the Vacuum Ultraviolet Spectral Range

We present a systematic approach to calculating the reflectance of aluminum thin films. In our approach, the rough aluminum surface is modelled as a square array of submicrometer-sized oblate cylinders. The focus of the study is on the vacuum ultraviolet (VUV) spectral range, with wavelengths ranging from 120 nm to 200 nm. The VUV reflectance of aluminum films is calculated by using the rigorous coupled wave approach in order to take the surface roughness of aluminum into account. The modelled reflectance spectra are compared to experimental data from unprotected and protected aluminum films.