Photoluminescence polarization and refractive index anisotropy of porous silicon nanocrystals arrays

Abstract

In this work, the simple way to form oriented arrays of silicon nanocrystals in a dielectric matrix was suggested. Porous silicon nanostructures obtained on the substrates with the [100] and [111] crystallographic orientations were separated from the silicon substrate using epoxy resin. Systems of the porous silicon nanoparticles were characterized by scanning electron microscopy, atomic-force microscopy, ellipsometry and luminescent spectroscopy. It is shown, that the use of epoxy resin suggests the preservation of the silicon nanostructures orientation after separation from the substrate. Based on the Bruggeman effective medium approximation, volume fractions of components of obtained nanosystems were determined for spherical and cylindrical shape of the porous silicon nanoparticles. The influence of the nanostructures orientation on optical and photoluminescent properties of the obtained nanosystems was studied. It is found that the photoluminescent polarization in silicon nanosystems is consistent with the anisotropy of their complex refractive index. Both phenomena originate from the morphological anisotropy of porous silicon nanocrystals.