Study of Luminescent Region in Anodized Porous Silicons by Photoluminescence Imaging and Their Microstructures

Abstract

The luminescent region in anodized porous silicon was examined by means of a photoluminescence imaging technique. It was found for the first time that the luminescence in the visible region originates from the topmost surface layer. This was confirmed not only by the surface photoexcitation but also by the excitation of the cleaved edge. This topmost surface layer does not show any diffraction spots with transmission-electron microscopy and is regarded as an amorphous layer. The microstructure of this layer observed by means of secondary-electron microscope (SEM) consisted of microparticles with the dimensions of 5∼30 nm, where the lower dimension is limited by the SEM resolution.