Symmetry of the Electronic States of Si Nanocrystals: An Experimental Study

Abstract

We apply photoluminescence polarization spectroscopy to study the symmetry of the electronic states of Si nanocrystals. Under resonant excitation, the degree of the linear polarization memory of porous Si luminescence is higher than that observed for nonresonant excitation. We observed an anisotropy of the polarization memory with respect to the crystalline axes. We discuss the polarization properties in terms of the symmetry of the ground state of the exciton. We demonstrate that the anisotropy with respect to the crystalline axes is linked to the warping of the heavy hole subband.