Black Al on SiON Prepared by Magnetron Sputtering

In this study, the electrical, morphological, and optical properties of thin aluminum films obtained by magnetron sputtering onto SiON layer were studied. It was found that the growth of Al films on SiON follows the Stranski–Krastanov mechanism. At the stage of 3D-growth, films with a cluster structure of Al grains and a pit/pore size of up to 20–50 nm are formed. For multilayer porous Al/SiON stacks, absorption of up to \(\sim 82\%\) in the range of 1–4.2 \(\mu\) m and a red shift with an increase in the number of layers are observed. The analysis of optical losses of porous Al films carried out by numerical modeling showed the presence of optical absorption bands with a linear increase in the position of the absorption maximum \(\lambda_{\textrm{max}}\) as the Al film thickness grows, as well as a shift of \(\lambda_{\textrm{max}}\) to the long-wave region with a decrease in the size of Al clusters and pores between them.