CC BY
15LM-O-17
Ultrashort laser-induced damage and ablation of silicon in water
and air environments
A. V. Bulgakov1'2. M. Stehlik1'3, I. Mirza1, O. Gatsa1, J. Hrabovsky1'4, N. M. Bulgakova1'2
1-HiLASE Centre, Institute of Physics of the Czech Academy of Sciences, Za Radnici 828, 25241 Dolni
Brezany, Czech Republic
2- S.S. Kutateladze Institute of Thermophysics SB RAS, Lavrentyev ave. 1, 630090 Novosibirsk, Russia
3- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, Marseille, France 4- Charles University, Faculty of Mathematics and Physics, Ke Karlovu 5, 121 16 Prague, Czech Republic
b ulgakov@fzu. cz
Pulsed laser ablation in liquids (PLAL) is an efficient and flexible technique for nanoparticle production and surface nanostructuring. Th e technique is simple in realization but involves complicated physical and chemical processes which are not fully understood. As a result, controllable PLAL fabrication of both colloidal nanoparticles and surface structures is still a challenge. This study investigates systematically, both experimentally and theoretically, damage and ablation of silicon irradiated by ultrashort laser pulses in air and water. The fundamental output of a PHAROS laser at a 1030-nm wavelength and with tunable pulse duration fro m 260 fs to 10 ps was used for ablation. The morphology of the laser -produced craters and the ablation volumes are analyzed by microscopy methods as a function of laser fluence and the damage and ablation thresholds are measured. Comparisons of femtosecond and picosecond pulses, single -shot and multi -shot irradiation regimes, and water and air environments are performed.
All threshold fluences in water are found to be considerably lower than the corresponding values in air. The efficiency of ps -laser ablation is strongly enhanced in water with the ablation depth being several times higher than that in air (Fig. 1) while fs ablation is shown to be suppressed by non-linear effects (self -focusing, plasma scattering) during laser pulse propagation in water. A t heoretical analysis of silicon heating and melting under the considered conditions is based on a two -temperature model and demonstrates that the observed deep craters under ps -laser ablation in water correspond to the silicon melting depth. Influences of t he pulse duration, surface reflectivity, focusing conditions, cavitation vapor bubble, and accumulation effects under multi -shot irradiation on silicon damage and ablation on ultrashort laser damage and ablation in water are discussed.
DISTANCE, |im DISTANCE, |im
Fig. 1. Confocal 3D microscopy images of spots produced by individual picosecond laser pulses (7 ps pulse duration) at a peak fluence of 3. 1 J/cm2 in air (a) and water (b) and the corresponding cross section profiles. The insets in the profiles show the cross section line across
the spots.
