29 May 2001 Simulation of picosecond pulsed laser ablation of silicon: the molecular-dynamics thermal-annealing model
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Abstract
A molecular-dynamics thermal-annealing model is proposed to study the mechanisms of ablation induced in crystalline silicon by picosecond pulses. In accordance with the thermal annealing model, a detailed description of the microscopic processes resulting from the interaction of a 308 nm, 10 ps, Gaussian pulse with a Si(100) substrate has been embedded into a molecular- dynamics scheme. This was accomplished by explicitly accounting for carrier-phonon scattering and carrier diffusion. Above the predicted threshold energy for ablation, Fth equals 0.25 J/cm2, ablation is driven by subsurface superheating effects: intense heating by the pulse leads to the thermal confinement of the laser-deposited energy. As a result, the material is overheated up to its critical (spinodal) point and a strong pressure gradient builds up within the absorbing volume. At the same time, diffusion of the carriers in the bulk leads to the development of a steep temperature gradient below the surface. Matter removal is subsequently triggered by the relaxation the pressure gradient as a large--few tens of nm thick--piece of material is expelled from the surface.
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Patrick Lorazo, Patrick Lorazo, Laurent J. Lewis, Laurent J. Lewis, Michel Meunier, Michel Meunier, } "Simulation of picosecond pulsed laser ablation of silicon: the molecular-dynamics thermal-annealing model", Proc. SPIE 4276, Commercial and Biomedical Applications of Ultrashort Pulse Lasers; Laser Plasma Generation and Diagnostics, (29 May 2001); doi: 10.1117/12.428006; https://doi.org/10.1117/12.428006
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