CORRELATION BETWEEN THE POROUS SILICON MORPHOLOGY AND THE PHOTOLUMINESCENCE EFFICIENCY - A SAXS STUDY

Small-angle X-ray scattering is applied to investigate the microstruct ure and the morphology of three photoluminescent porous silicon sample s of the same porosity (80%) but prepared using different electrochemi cal treatments: (A) as-prepared, (B) as-prepared 65% porosity, followe d by an oxidation treatment and an oxide dissolution in HF, (C) as-pre pared 65% porosity followed by a HF dissolution. Although the PL spect ra are almost similar in energy, there are differences in their intens ities: the luminescence intensity of the as-prepared sample A is a bit greater than the one observed for sample B and much more greater than the one corresponding to sample C. If one assumes the same surface pa ssivation (Si-H) for the three samples then these differences in lumin escence intensity may be due to the different PS morphologies which ar e evidenced in SAXS curves at low q values.