Localized generation of high-density plasmas in engineered semiconductor nanostructures using femtosecond laser pulses

There has been a recent interest in femtosecond-laser-assisted reshaping of the pre-engineered Si nanostructures via free-carrier generation in, and subsequent ablation of, semiconductor materials. Our experimental results indicate that the intensity of a localized electric field in the meta-surface leads to ablation and subsequent localized modification of the structure and the formation of high-aspect nanoscale trenches in Si. Our simulation attributes these effects to tightly-localized electron hot spot produced by multi-photon and tunneling ionization of Si atoms. In this work, we present experimental results and theoretical modeling of the electron dynamics – from ionization to material ablation – in a crown-shaped silicon meta-surface using 3D particle-in-cell simulation code. The result of a series of simulations carried out for different trench depths and widths will be presented, and their relevance to replicating the experimentally observed trenching process will be discussed.