Photoluminescence of laser ablated silicon

The change in silicon morphology can induce silicon to luminescence in the visible spectrum range. Several examples were reported; porous silicon[1], spark eroded silicon[2], and plasma deposited silicon cluster[3]. In this report we used a Nd-YAG laser to ablate single crystal silicon, and anodically prepared porous silicon. The ablated sites were subjected to photoluminescence measurement. The 325 nm line of He-Cd laser was used for excitation, and a photoluminescence spectrum with a peak at about 450 nm was obtained. However, this peak was only observed after the samples were exposed to air for several days. The violet photoluminescence spectrum was considered to be due to room temperature annealing of ablated sites.