Kinetics and mechanism of electrochemical formation of porous surface layers on silicon in hydrofluoric acid. Influence of illumination on the kinetics and mechanism of anodic porous-layer formation on n-type silicon

Illumination lowers the rate of porous-layer formation under galvanostatic polarization, so that the linear and parabolic kinetics found in the dark is transformed to linear kinetics. Under the effect of light, oxidation of silicon to the divalent state is the predominant reaction; this promotes formation of a more porous structure because of inhibition of the growth of macropores taking place in the dark when silicon dissolves to tetravalent compounds.