Effect of Post-processing on Photoluminescence and Surface Composition of Porous Silicon

Porous silicon (PS) with 6.13 nm average pore diameter, 20.6μm thickness layer and 70.8% porosity prepared by galvanostatic electrochemical anodisation of p-type silicon wafer in aqueous hydrofluoric acid (HF)/ethanol electrolyte. The freshly prepared PS was processed by time effect, nitric acid treatment, cathodic reduction, and hydrogen peroxide treatment, respectively. Samples were characterized and analyzed by field emission scanning electron microscopy (FESEM), P hotolumimescence (PL) and X-ray photoelectron spectroscopy (XPS) before and after post-processing. The PL spectra showed that PS had three PL peaks near to 425 nm, 486 nm and 530 nm, respectively, the strongest luminous intensity at 425nm obtained when PS followed 6h in hydrogen peroxide post-processing, and the difference effect on PL via various post-processing were also discussed. From XPS spectra analysis, the surface composition of PS via different post-processing method was carried out that the oxygen mainly existed in the form of Si-O.