Effect of the duration of electrochemical anodization on the microhardness of macroporous silicon

The dependence of the microhardness $H$ of macroporous silicon layers formed on the duration $t_{\mathrm{an}}$ of electrochemical anodization at a constant current density of $J$ = 20 mA/cm$^2$ is studied. It is shown that the nonlinear run of the dependence $H(t_{\mathrm{an}})$ is due to the influence exerted on the microhardness not only by the surface density of pores, but also by the single-crystal base at $L<$ 10$h$, where $L$ and $h$ are the thickness of the porous layer and the depth of indenter penetration, respectively.