Formation of channel silicon to create filter layers

The features of the formation of porous layers on substrates of low doped silicon of $n$-type conductivity by anodic etching using illumination are considered. The formation of microporous silicon layer on the walls of macropores was found. It is shown that the illumination modes strongly influence the morphological parameters of the obtained layers. After exposure to alkali, macroporous layers with pore diameters up to 550 nm were obtained, which can be used to create filter layers.