Strong polarization-dependent photoluminescence from silicon nanowire fibers

Fibers of highly oriented Si nanowires (SiNWs) were formed by drawing from a condensed SiNW suspension. The SiNW fiber, excited at 514.5nm, produces a strong photoluminescence (PL) at room temperature. The PL spectrum shows three bands at 565–580, 605–640, and 680–690nm, respectively, which are consistent with the PL of porous silicon. The relative intensity of these bands and the integrated intensity of the PL vary with the angle θ between the electric field of the polarized laser excitation and the fiber axis. The dependence on θ is attributed to the combined effects of the one-dimensional shape of the SiNW and the large dielectric contrast between the SiNW and the ambient.