Evolution of photoluminescence and chemical composition of the nanostructured silicon in water solutions

Modification of the IR absorption spectra and photoluminescent properties of nanoporous silicon as a result of its interaction with water solutions is investigated. The effect of air pre-oxidation and the solution pH on the interaction is studied. It is found that the reaction of silicon dissolution dominates at the first stage of water treatment, while the formation of the stoichiometric silicon oxide occurs at the second one. Thereafter, the properties of nanoporous silicon are stabilized. The pre-oxidation extent of the sample is found to determine the stabilization time for its properties and the ultimate photoluminescence (PL) parameters. Variation of the solution pH from 4 to 8.5 affects only the evolution rate of the PL spectra. The modifications of the nanostructured silicon PL spectra are explained within the quantum-size model of luminescence. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)