Laser plasma interaction at an early stage of laser ablation

Y. F. Lu, M. H. Hong, T. S. Low

Research output: Contribution to journalArticle

30 Citations (Scopus)

Abstract

Laser scattering and its interaction with plasma during KrF excimer laser ablation of silicon are investigated by ultrafast phototube detection. There are two peaks in an optical signal with the first peak attributed to laser scattering and the second one to plasma generation. For laser fluence above 5.8 J/cm2, the second peak rises earlier to overlap with the first one. The optical signal is fitted by a pulse distribution for the scattered laser light and a drifted Maxwell-Boltzmann distribution with a center-of-mass velocity for the plasma. Peak amplitude and its arrival time, full width at half maximum (FWHM), starting time, and termination time of the profiles are studied for different laser fluences and detection angles. Laser pulse is scattered from both the substrate and the plasma with the latter part as a dominant factor during the laser ablation. Peak amplitude of the scattered laser signal increases but its FWHM decreases with the laser fluence. Angular distribution of the peak amplitude can be fitted with cosn θ(n=4) while the detection angle has no obvious influence on the FWHM. In addition, FWHM and peak amplitude of plasma signal increase with the laser fluence. However, starting time and peak arrival time of plasma signal reduce with the laser fluence. The time interval between plasma starting and scattered laser pulse termination is proposed as a quantitative parameter to characterize laser plasma interaction. Threshold fluence for the interaction is estimated to be 3.5 J/cm2. For laser fluence above 12.6 J/cm2, the plasma and scattered laser pulse distributions tend to saturate.

Original languageEnglish (US)
Pages (from-to)2899-2903
Number of pages5
JournalJournal of Applied Physics
Volume85
Issue number5
DOIs
StatePublished - Jan 1 1999

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laser plasma interactions
laser ablation
lasers
fluence
pulses
arrivals
optical communication
phototubes
plasma generators
Boltzmann distribution
scattering
excimer lasers
center of mass

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Laser plasma interaction at an early stage of laser ablation. / Lu, Y. F.; Hong, M. H.; Low, T. S.

In: Journal of Applied Physics, Vol. 85, No. 5, 01.01.1999, p. 2899-2903.

Research output: Contribution to journalArticle

Lu, Y. F. ; Hong, M. H. ; Low, T. S. / Laser plasma interaction at an early stage of laser ablation. In: Journal of Applied Physics. 1999 ; Vol. 85, No. 5. pp. 2899-2903.
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