Mechanism of porous tungsten nanostructure formation by pulsed laser deposition

Pulsed laser deposition (PLD) is a technique that allows the formation of thin films on various materials. In this study, we focused on metal tungsten thin film formed via PLD under relatively high argon pressure (50 and 100 Pa). It is shown that porous nanostructured thin films can be formed by controlling the background gas pressure and the distance between the ablation target and the substrate. To demonstrate the formation process, three-dimensional Monte Carlo particle simulation is performed by introducing directional motion and surface adhesion probability to randomly diffusing particles. It is discussed that the porous structures are formed with a top-down process, and the diffusion-limited aggregation (DLA) process likely governs the formation of porous structures.