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Proceedings Paper

Molecular-dynamics simulations of picosecond pulsed laser ablation and desorption of silicon
Author(s): Patrick Lorazo; Laurent J. Lewis; Michel Meunier
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Paper Abstract

Molecular-dynamics simulations are used to investigate single- shot pulsed laser ablation and desorption of crystalline silicon. The motion of approximately 32000 atoms, contained in a 5 X 5 X 27 nm3 surface rectangular box irradiated by a single 308 nm, 10 ps, Gaussian laser pulse is followed on the picosecond time scale. Because melting and, possibly, ablation or desorption of the target following absorption of the laser pulse are described within the thermal annealing model, care is taken not to exceed carrier densities of approximately 1022 cm-3. More precisely, the interaction of photons with the target is thought to cause the generation of a dense gas of hot electrons and holes which thermalizes, at first, on a time scale of a few tens of femtoseconds through carrier-carrier scattering. These hot photocarriers then transfer their kinetic energy to the lattice by means of carrier-phonon interactions characterized by a very fast initial cooling rate. The result is the creation, above a characteristic threshold energy, of a plume containing single atoms and clusters leaving the target with high axial velocities. Preliminary results about the melting fluence threshold and mechanisms underlying ablation are presented. Carrier diffusion is found to be an essential mechanism for relaxation and is presented as a possible cause of subsurface boiling.

Paper Details

Date Published: 23 March 2000
PDF: 10 pages
Proc. SPIE 3935, Laser Plasma Generation and Diagnostics, (23 March 2000); doi: 10.1117/12.380792
Show Author Affiliations
Patrick Lorazo, Ecole Polytechnique de Montreal and Univ. de Montreal (Canada)
Laurent J. Lewis, Univ. de Montreal (Canada)
Michel Meunier, Ecole Polytechnique de Montreal (Canada)

Published in SPIE Proceedings Vol. 3935:
Laser Plasma Generation and Diagnostics
Richard F. Haglund; Richard F. Wood, Editor(s)

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