Effect of insitu annealing on physical properties of Si nanoparticles synthesized by pulsed laser ablation

Silicon nanocrystalline particles with a uniform size were successfully synthesized by a sequential system of pulsed-laser ablation, insitu annealing and a size classification using a differential mobility analyzer (DMA). Transmission electron microscopy (TEM) observations revealed that the insitu annealing was quite effective in improving morphological uniformity of the particles; most of the nanoparticles annealed above a temperature of 900 C showed a spherical shape. The silicon nanoparticles classified after the annealing showed a very narrow size-distribution with a geometrical standard deviation of approximately 1.1. Raman scattering measurement and high-resolution TEM observation showed that the annealing was also effective in improving a crystallinity of the particles. The silicon nanoparticles showed photoluminescence (PL) in near-IR and visible region at room temperature, which depended on the insitu annealing condition; the full-width at half-maximum (FWHM) of the PL spectrum decreased with the increase in annealing temperature and reached as narrow as 190 meV corresponding to the sharp size distribution of the emitting particles.