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8 October 2004 Formation of self-organized regular nanostructures upon femtosecond laser ablation
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Proceedings Volume 5662, Fifth International Symposium on Laser Precision Microfabrication; (2004) https://doi.org/10.1117/12.596765
Event: Fifth International Symposium on Laser Precision Microfabrication, 2004, Nara, Japan
Abstract
At the bottom of ablation craters produced in many materials, e.g. dielectric and silicon crystals, by the impact of femtosecond laser radiation, regular periodic structures are observed with a feature size at the order of a few 100 nanometers, much smaller than the incident wavelength. Their orientation depends strongly on the laser polarization but not on any intrinsic crystalline parameters. An increasing number of shots results in higher contrast, better developed structures, indicating a positive feedback. The region around the impact is shown, by micro Raman spectroscopy, to undergo phase transformations like under high pressure. The structure spacing appears to depend crucially on the depth of the perturbed volume, i.e. the incident (and absorbed) energy. All observations suggest that the structures form by self-organization from instabilities induced in the material by the laser input. A general picture suggests that the irradiation results in a rapid, non-equilibrium destabilization of the crystal structure, which should not be confused with melting as a classical thermodynamic process (i.e. temperatures defined as equilibrium properties). Relaxation from this instability results in the self-assembly of the observed structures. Theoretical simulations demonstrate the feasibility of this model, which also is corroborated by comparison to other unstable situations.
© (2004) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Juergen Reif, Florenta A. Costache, Sebastian Eckert, Simona Kouteva-Arguirova, Michael Bestehorn, Ionut Georgescu, Alexandre F. Semerok, Philippe Martin, Olivier Gobert, and Winfried Seifert "Formation of self-organized regular nanostructures upon femtosecond laser ablation", Proc. SPIE 5662, Fifth International Symposium on Laser Precision Microfabrication, (8 October 2004); https://doi.org/10.1117/12.596765
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