SAXS STUDY OF THE INFLUENCE OF THE POROUS SILICON MORPHOLOGY ON THE PHOTOLUMINESCENCE EFFICIENCY

In this study, we applied small-angle X-ray scattering to investigate the microstructure and the morphology of photoluminescent porous silic on samples prepared by different ways, i.e. highly porous silicon laye rs produced by electrochemical dissolution of bulk Si in HF, and also lower-porosity layers subsequently oxidized by electrochemical anodisa tion. The modification which occurs in the scattering pattern after an oxidation treatment indicates the formation of a oxide monolayer at t he interface pore-matter. The microstructure obtained after dissolutio n of this oxide layer in HF is compared with the one of a porous silic on having the same porosity but prepared by electrochemical dissolutio n. Differences between the scattering profiles appear in the region cl ose to the angular origin which corresponds to large particles (voids or Si skeleton), although the part of the curve corresponding to the p ore surface remains similar.