Induced stress arising in crystalline silicon under exposure to ultra-short laser pulses of different duration in air and water

The silicon surface was modified in a single-pulse mode with femto-picosecond laser pulses (0.3 and 10 ps) in the near-IR range (1030 nm) during ablation in air and water. The resulting structures were studied using Raman microscopy. In the course of the study, it was found that nanocrystallites with a size of 7–8 nm appear at the crater boundary. Local mechanical stresses were found in the center of the crater, the sign of which depends on the applied energy density. The highest local compressive stresses arise in water in the subfilamentation mode at maximum energy densities.