Silicon Surface Modifications Induced by Single Femtosecond Laser Pulses at Minimally Disruptive Fluences in Air and Water

Silicon surface modifications induced by single femtosecond laser pulses at minimally disruptive fluences near melting threshold in air and water are investigated using atomic-force microscopy. At threshold fluence the modified surface in air is presented by chaotically-located nanobumps and nanopits, while in water they appear to be circumferentially-spaced. Phenomena of cracking, corrugated surface and eruption of material are also observed.