Large current density and anodization time needed for strong photoluminescence in porous silicon

We investigated the relation between anodization conditions and photoluminescent characteristics including spatial variations. The current density was between 7.9 and 39 mA cm−2, and the anodization time between 10 and 60 min. We clarified a generous tendency as follows: as the current density or the anodization time increases, the edge of the anodized area gives the stronger photoluminescence at first, and then the center also gives the stronger photoluminescence. In addition, we reported the difference between luminescing and non-luminescing porous silicon, from the aspects of photoluminescent, photoacoustic, and Raman spectra.