XPS, USXS and PLS investigations of porous silicon

X-ray photoelectron spectra (XPS) as well as ultrasoft X-ray spectra (USXS) of porous silicon have been investigated. The samples were obtained by electrochemical etching of silicon plates in an alchohol solution of HF. Silicon 2p core states and Si 1(2,3) spectra of 'as-obtained' samples as well as those annealed in the atmosphere were obtained. All the samples show an increase of oxidation in porous layers with temperature. However, the degree of oxidation in the sample annealed at high temperatures for 20 sec is less than that annealed for 20 min at lower temperatures. (C) 1998 Elsevier Science B.V.