Determination of the nucleation region of Si particles produced by pulsed-laser deposition in Monte Carlo simulation

The nucleation and growth of Si nanoparticle produced by pulsed laser ablation in helium gas ambient is investigated via direct simulation Monte Carlo method with a real physical scale of target-substrate configuration. The nucleation area is important for the formation of Si nanoparticles, and the average size and size distribution of Si nanoparticles formed in this region depend on its range. The narrower the nucleation area and, therefore, the less the maximum times of collisions between Si atoms in the region, the smaller and the more uniform the Si nanoparticles. A nucleation and growth process is clearly observed. It is shown that the nucleation region and the nucleation growth internal is changing with time. The ambient gas pressure is important to nucleation region. The suitable pressure range under certain conditions is given and our simulated results are approximately in agreement with the previous experimental data.