A Study on Michanism of VisibLe Luminescence From Fbrous SiLicon

AbstractThe efficient visible tight emitting porous silicon was made using the standard method of anodic oxidation. The characteristic photoluminescence spectra and Raman Scattering spectra of the porous silicon were obtained. A kind of stable yellow powder (not the fragments of the porous silicon thin film the porous structure was still on the crystalline silicon substrate) was taken off from the visible light emitting porous silicon with nonchemical method. The powder can not dissolve in water, alcohol, acetone and some other common solvents, and it still emits efficient visible light after further grinding. The PL spectrum of the powder shows the same peak position, the same shape and the same FW-M as that of the porous silicon wafer. The microstructure of the porous silicon wafer and the microscopic shape of thepowder were studied using the scanningelectron microscopy (SEM) The X–ray photoelectron spectroscopy MSP) shows that the fluorescent powder in the surface layer of the porous silicon is composed of many kinds of elements, such as Si, Q a N and so on. The Si content is only 50% or less in the surface layer of porous silicon. The above–mentioned experiments were performed again on the unpolished surface of the single crystal silicon substrate. So we suggest that the visible luminescence of the porous silicon is from the fluorescent powder maybe not due to the quantum confinement effect in the nm–scate crystalline silicon pillars.