In Situ Measurements of Water Immersion and UV Irradiation Effects on Intensity and Blue Shift of Visible Photoluminescence in Porous Si

It has been found by in situ measurements that immersion in deionized water and simultaneous uv irradiation of porous silicon can cause a considerable change in emission intensity and a blue shift in visible (yellow) photoluminescence. It was determined that the blue shift is mainly due to reduction in size and surface alteration by oxidation of porous Si and that an initial increase and subsequent decrease in intensity is due to competition between surface passivation and generation of nonradiative recombination centers by the oxidation. After prolonged irradiation, a new blue emission was observed in place of the yellow emission. Excitation spectra for the yellow photoluminescence were also investigated.