Photoluminescence properties and size distribution in laser synthesized Si nanopowders for optoelectronic devices

Small-angle neutron scattering (SANS) and transmission electron microscopy (TEM) have been used to investigate the correlation between photoluminescence properties and particle size distributions in laser synthesized Si nanopowders, of interest for application in optoelectronics. The Si nanoparticle volume distributions obtained from the SANS data are in good agreement with the TEM histogram for particle diameters ranging between 30 and 200, Å approximately. Furthermore the SANS data confirm that, as it is known from photoemission spectra, in the case of highly luminescent powders a secondary distribution of particles ranging between 10 and 20 Å approximately (hardly visible by TEM) is present. Finally the SANS data analysis suggests that tiny inhomogeneities (5-10 Å in diameter), possibly micropores which may have relevant consequences on material performance, are also present in all the investigated samples.