Circular ripple formation on the silicon wafer surface after interaction with linearly polarized femtosecond laser pulses in air and water environments
Autor: | R. Goodarzi, F. Hajiesmaeilbaigi |
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Rok vydání: | 2018 |
Předmět: |
Materials science
Silicon Ripple Physics::Optics chemistry.chemical_element 02 engineering and technology 01 natural sciences Fluence law.invention Optics law 0103 physical sciences Electrical and Electronic Engineering Ultrashort pulse laser 010302 applied physics business.industry Ponderomotive force 021001 nanoscience & nanotechnology Laser Atomic and Molecular Physics and Optics Electronic Optical and Magnetic Materials Wavelength chemistry Femtosecond 0210 nano-technology business |
Zdroj: | Optical and Quantum Electronics. 50 |
ISSN: | 1572-817X 0306-8919 |
Popis: | Ultrashort laser pulse interaction with the surface of silicon wafer in air and water environments is investigated. Ti:sapphire laser with 40 femtosecond laser pulses at 790 nm and 10 Hz repetition rate was used. The ablation threshold of the silicon surface in the air was determined to be about 0.28 J cm−2. The surface morphology was studied by using scanning electron microscope images. The size of the regular ripples formed in the air environment is a little smaller than the laser wavelength. Due to the nonlinear interaction and self-focusing before the target, the ripples size reduced to nearly a half of the laser wavelength in the water. Moreover, the spikes’ structure formation and their diameter in air and water were studied. Two regimes for spike formation in water are proposed that can explain the anomalous decrease of the spikes’ diameter in higher fluence. During the interaction of single linearly polarized femtosecond laser pulse with the surface, an irregular ripple formation that called circular ripple is observed. This structure which is a result of radiation pressure implies to the surface by the end of the pulse. A new physical model for interpretation of the circular ripples formation based on the ponderomotive force of an ultrashort pulse laser is proposed which can predict the size of the circular ripples. The calculated results are in accordance with our experimental findings. |
Databáze: | OpenAIRE |
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