Temporal- and site-specific determination of the origin of the luminescent bands in silicon nanowires

We have performed temporally resolved X-ray excited optical luminescence measurements on Si nanowires. By performing Si K edge X-ray excitation measurements we have determined that the short-lifetime components have primarily Si character, while the long-lifetime component stems from the SiO(2) shell and SiO(2)-Si interface. The lifetime of the short-lifetime component decreases with increasing luminescence energy, i.e., as the size of the nanosilicon species decreases.