Effects of Light Exposure during Anodization on Photoluminescence of Porous Si

Photoluminescence study has been carried out on porous Si which has been prepared from p-type Si wafers either by anodization under light illumination (photoanodization) or by anodization in the dark. It has been found that the photoanodization makes the luminescence peak wavelength shorter and the luminescence intensity stronger. As a result of these effects, visible red light luminescence has been reproducibly obtained. These effects have been found to be more pronounced when highly concentrated HF solutions are used for anodization. Scanning electron microscopy and Raman spectroscopy showed no distinct differences in microstructure or crystallinity between the photoanodized and in-dark anodized porous Si.