Multipulse irradiation of silicon by femtosecond laser pulses: Variation of surface morphology

S. Lugomer, A. Maksimović, B. Farkas, Z. Geretovszky, T. Szörényi, A. L. Tóth, Z. Zolnai, I. Bársony

Research output: Article

10 Citations (Scopus)

Abstract

The multipulse interaction of ultraviolet femtosecond laser pulses with silicon and generation of surface structures in a large area spot (≳1 mm 2 ) has been studied. The evolution of multiscale structures at the constant fluence strongly depends on the number of pulses, N. For N < 200, the "carpet-like" pattern of nano-, and micro-spikes is generated by the bubble explosion in a thin surface foam layer. The accumulation of bubbles and their explosion due to repetition of laser pulses cause damped membrane-like oscillations of the silicon surface. For 200 ≤ N, bifurcation of surface morphology takes place: (i) the surface tension waves of the wavelength ∼200 μm appear in the peripheral region of the spot. Generated by the surface thermal gradient in the liquid foam layer, they spread from the hot centerline towards the periphery of the spot. The change of their wavelength with propagation distance indicates onset of the Eckhaus instability caused by the phase modulation in multipulse interaction. (ii) Deep caverns appear in a highly superheated silicon layer in the central region of the spot due to the fast gas-liquid phase separation and the fragmentation process.

Original languageEnglish
Pages (from-to)3589-3597
Number of pages9
JournalApplied Surface Science
Volume258
Issue number8
DOIs
Publication statusPublished - febr. 1 2012

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ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics
  • Physics and Astronomy(all)
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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