Femtosecond-Laser-Ablation Dynamics in Silicon Revealed by Transient Reflectivity Change

The dynamics of ablation in monocrystalline silicon, from electron-hole plasma generation to material expansion, upon irradiation by a single femtosecond laser pulse (1030 nm, 300 fs pulse duration) at a wide range of fluences is investigated using a time-resolved microscopy technique. The reflectiv...

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Bibliographic Details
Published in:Micromachines (Basel) 2021-12, Vol.13 (1), p.14
Main Authors: Feng, Tao, Chen, Gong, Han, Hainian, Qiao, Jie
Format: Article
Language:English
Subjects:
Ablation
Drude model
Evolution
femtosecond laser ablation
Femtosecond pulses
Fluence
Holes (electron deficiencies)
Investigations
Laser ablation
Lasers
Phase transitions
Plasma
Pulse duration
Reflectance
Refractivity
Silicon
silicon laser ablation
Temperature dependence
two ablation regimes
two-temperature model
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Summary:The dynamics of ablation in monocrystalline silicon, from electron-hole plasma generation to material expansion, upon irradiation by a single femtosecond laser pulse (1030 nm, 300 fs pulse duration) at a wide range of fluences is investigated using a time-resolved microscopy technique. The reflectivity evolution obtained from dynamic images in combination with a theoretical Drude model and a Two-Temperature model provides new insights on material excitation and ablation process. For all fluences, the reflectivity increased to a temporary stable state after hundreds of femtoseconds. This behavior was predicted using a temperature-dependent refractive index in the Drude model. The increase in velocity of plasma generation with increasing fluence was theoretically predicted by the Two-Temperature model. Two ablation regimes at high fluences (>0.86 J/cm ) were identified through the measured transient reflectivity and ablation crater profile. The simulation shows that the fluence triggering the second ablation regime produces a boiling temperature (silicon, 2628 K).
ISSN:2072-666X
2072-666X
DOI:10.3390/mi13010014