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Communication Dans Un Congrès Année : 2006

Dynamics of femtosecond laser-induced cluster emission from silicon

Résumé

Ultrashort laser pulses have opened unique opportunities for studying mechanisms of laser-matter interactions by analyzing particles emitted from the irradiated surfaces. A number of recent experiments indicate that efficient emission of clusters can occur under certain conditions of fs-laser ablation/desorption of semiconductors. Analysis of cluster emission could provide a considerable insight into the complex interplay of thermal and ultrafast, non-thermal processes in the laser-irradiated targets. Here we report time-resolved pump-probe measurements of the yield of singly-charged positive cluster ions (n = 2-11) from a silicon surface and theoretical modeling of the laser-induced excitation of the Si target for the experimental regimes. A 80-fs Ti:sapphire laser pulse was split into two subthreshold pulses with a variable time delay and cluster emission was monitored after each pair of pulses. When temporal separation between the pulses is around few hundred femtoseconds, the emission is found to be stronger than that with a single laser pulse of the same total energy. We demonstrate also that there is significant incubation in silicon in respect of cluster yield which is maximized after 30-40 pulses applied to the same spot. Temporal and spatial behavior of electron and ion temperatures in the Si target as well as surface charge density were simulated as a function of pump-probe delay. Both modeling results and observations imply a new mechanism of cluster emission involved. We suggest that the first pulse induces the lattice destabilization and surface structural changes while the second pulse, applied to the unstable surface, acts as a trigger resulting in efficient emission of clusters. The role of surface defects and premelting in cluster formation process will be discussed.
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Dates et versions

hal-01896824 , version 1 (16-10-2018)

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  • HAL Id : hal-01896824 , version 1

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Alexander V. Bulgakov, Igor Ozerov, Wladimir Marine. Dynamics of femtosecond laser-induced cluster emission from silicon. Laser Applications in Microelectronic and Optoelectronic Manufacturing XI, Jan 2006, San Jose, California, United States. ⟨hal-01896824⟩
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