Laser induced degradation of photoluminescence intensity of porous silicon

The evolution, under vacuum, of the photoluminescence (PL) intensity of por ous silicon (PS) has been studied as function of anodisation conditions, la ser line and post-anodisation treatments. It was shown that the degradation of the PL intensity depends on the internal structure of PS. In particular , the degradation is important for PS layers formed essentially by crystall ites having small size or where amorphous phase exists. The experimental re sults have been interpreted using a theoretical model, which takes into acc ount the variation with time of the local concentration of the luminescent centers.