Effects of Laser Fluence on Surface Nanostructuring With a Laser-Assisted Scanning Tunneling Microscope

In this work, molecular dynamics simulation is performed to explore the long-time (up to 5 ns) behavior of argon crystal in surface nanostructuring with a laser-assisted scanning tunneling microscope. The surface nanostructuring region is limited to tens of nanometers in diameter although the simulated systems are much larger (more than 300,000 of atoms inside). This study is focused on the long-time solidification and crystallization procedure, which is driven by the heat conduction in the material. The effect of the computational domain on the final nanostructuring result is studied in detail. Different laser fluences are used in the simulation to explore how and to what extent the energy input affects the dimension and profile of the surface nanostructure. Meanwhile, spot-like structural defects in the sub-surface region are investigated during the solidification. Additionally, the evolutions of surface melting depth and lowest position in the whole process reveal the impact of different laser fluence on surface nanostructuring from another aspect.