Obtaining a colored nanostructured layer of amorphous silicon by etching in chlorine-containing plasma

It is shown that in the self-forming mode in the plasma etching process of amorphous silicon structures ($\alpha$-Si)/SiO$_2$/Si and ($\alpha$-Si)/Pt/SiO$_2$/Si in chlorine-containing plasma (Cl$_2$/Ar), it is possible to obtain a multicolored surface from nanoconus and nanowire structures of $\alpha$-Si. The mechanism of formation of such structures during plasma chemical etching is discussed. The reflection spectra of colored films are given. The bright colors of the surface are caused by the resonant reflection of light in the layers of nanoconus and nanowire structures of $\alpha$-Si with a sublayer of $\alpha$-Si nanometer thickness.