Correlation between the photoluminescence and chemical bonding in porous silicon

The changes in the visible photoluminescence and Raman spectra of n-type porous silicon as a result of rapid thermal annealing and chemical treatment have been studied. Modification of the chemical bonds due to these treatments has been observed by X-ray photoemission spectroscopy. Our results show that the change in the luminescence spectra of porous silicon is related to the modification of the chemical bonds and that complexes such as the terminations in siloxene as well as silicate molecules play a role in determining the optical properties of this new photonic material. The surface containing siloxene-like bonding exhibits very intensive photoluminescence. The presence of silicates leads to a decrease in luminescence intensity and to the appearance of a weak high energy band in the photoluminescence spectra.