Molecular Dynamics Simulation of Laser Ablation Phenomena.

Abstract

Some results of a molecular dynamics simulation of the atomic behavior of metals and silicon during laser ablation are introduced. Many small voids are at first generated in the liquid phase. They then become larger and larger, and adjacent voids combine with each other, developing into a larger void. Finally, the surface begins to bulge out, forming into relatively large lumps. In metals undergoing laser irradiation of relatively high power density, the molten metal, whose kinetic energy is too low for evaporation to occur, becomes spherical due to the surface tension and is deposited around the hole. On the other hand, in the case of relatively low power density, fusing atoms flow out from the molten pool and deposit around the hole. In silicon, some of the vaporizing atoms are deposited around the hole, which is smaller in diameter than that in metals under the same irradiating conditions. The surface of the generated wall of silicon is rough compared to that of metal.