Photoluminescence of porous silicon layers oxidized in controlled water vapor conditions.

A study of the evolution of the photoluminescence spectra features on chemically treated and controlled aged porous silicon layers (PSL) prepared by the electrochemical method is presented Room temperature photoluminescence (PL) spectra of freshly prepared PSL show a characteristic peak located at similar to 700 nm. The PL spectrum of chemically oxidized and successively water vapor oxidized PSL strongly modifies compared to the PL spectra of freshly prepared samples. Those variations are associated with the changes on the PSL structure induced by the applied oxidization processes. The evolution of the characteristic PL features gives us the ability to identify the signal due to the quantum size effect (QSE) and to assign high energy transitions produced by some kind of defect centers.