On surface plasmons in porous silicon: Measurements of the electron energy loss in etched silicon nanocrystals

Surface plasmons resulting from the interaction of the electron beam of a transmission electron microscope with porous silicon nanoparticles were measured. The inelastic scattering of fast electrons in H-covered silicon nanocylinders shows a peak at similar to 5.5 eV. A gradual decrease of the first and second order plasma volumetric absorption simultaneous with a constant surface mode absorption amplitude was measured for decreasing silicon-slab thicknesses, Competitions between bulk and surface effects show, for the volume mode peak at 16.9 eV, a damping factor increase of similar to 5 eV. The measured silicon particle diameter was similar to 15 Angstrom and a value of the dielectric constant is estimated from the surface plasmon data at 8.5, which is in agreement with recent theoretical work on the modified dielectric constant in quantum confined systems. (C) 1996 American Institute of Physics.