Size distribution and surface characteristics of silicon nanoparticles

The size distribution and morphology of silicon nanoparticles have been studied using small-angle X-ray scattering (SAXS) and transmission electron microscopy. Quantitative agreement was established between the results of the two methods. The surface characteristics, as well as the size distribution, were found to be independent of the choice of binder material used to prepare printed layers containing the nanoparticles. Intrinsic silicon nanoparticles, produced by laser pyrolysis of silane, have been shown to have a narrow, effectively monodisperse, size distribution and to be roughly spherical in shape. SAXS measurements indicate that the particles have a regular geometry and a smooth surface. There is, however, a thin disordered region at the surface of the particles. Particles produced by milling of bulk silicon have surface fractal characteristics and a high dispersivity resulting from the milling process, in which the particles become smoother as they are milled to smaller size or for longer periods. The size dispersion, but not the median size, is similarly reduced by milling for longer periods