Electrochemical “resonance” of photoluminescence for porous silicon formed using pulsed current anodization

Porous silicon is formed using pulsed current with a pulse modulation varied in a range spanning five orders of magnitude, starting from a hundredth of a second, in order to achieve modulation of the properties of PS on the nanoscale. The PS is characterized by performing photoluminescence (PL), paramagnetic, and charge transport measurements. We find that the properties of prepared PS are greatly affected by the modulation period applied and depend on it in a nonmonotonic way. The intensity of orange-red PL exhibits a resonance-like behavior reaching a maximum at the modulation period in the range of 0.1–0.25 s. A correlation between the variation in PL intensity and the electron paramagnetic resonance signal is noticed. We show that PS with a porosity of 50% and a distance between pores of 10 nm is mainly consists of air and silicon oxide. In the prepared PS, the silicon, in the form of granules with a diameter of $\approx$ 1.5 nm arranged in chainlets, has a volume fraction on the order of 1%.