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Improvement of ablation capacity of sapphire by gold film-assisted femtosecond laser processing
摘要： Sapphire is widely used in civilian and military equipment owing to its superior optical and mechanical properties. Femtosecond laser has been demonstrated to be an effective tool to process sapphire material. However, the direct processing of sapphire by femtosecond laser still meets some challenges, such as poor ablation morphology and low laser energy absorption. In this work, femtosecond laser processing of sapphire coated with a 12-nm-thick gold film (Au-coated sapphire) has been investigated. The experimental results have revealed that the ablation morphology of Au-coated sapphire has been improved, featuring fewer molten materials and thermal cracks, as well as regular crater shape and uniform periodic surface structures. It has also been found that, under 100 shots condition, the threshold fluence of Au-coated sapphire is reduced by about 56% compared to that of uncoated one. Meanwhile, the incubation effect of Au-coated sapphire is stronger than that of uncoated one. We also illustrate that the material removal rate of Au-coated sapphire is increased up to about two times higher than that of uncoated one. In order to reveal the effective mechanism of the gold film in the laser processing of sapphire, the energy transfer process among incident photons, free electrons and sapphire lattice phonons was studied. Our study provides a guidance for improving the laser ablation capacity of sapphire.
关键词： Gold film,Sapphire,Material removal rate,Ablation morphology,Femtosecond laser processing
更新于2025-09-19 17:13:59
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Solvents Effect on the Morphology and Stability of Cu/CuO Nanoparticles Synthesized at High Fluence Laser Ablation
摘要： Cu/CuO NPs were synthesized by ablating Cu target using nanosecond Nd:YAG pulsed laser operating at 1064 nm with 8 ns pulse duration in three different solvents viz: ethylene glycol (EG), deionized water (DI) and ethanol (Eth). The effects of these three solvents at high laser fluence of 40 J/cm2 was investigated to study the stability and morphology of nanoparticles using microscopic and spectroscopic techniques. The morphology of these nanoparticles are dependent on the physical properties of solvents (like viscosity, conductivity, polarity and enthalpy) used in laser ablation. EG and DI shows tadpole and necklace like structure whereas in Eth hollow structures were observed. The crystallinity of nanoparticles were confirmed by HRTEM, SAED and XRD analysis. In all the three solvents the characteristic absorption and emission peaks of Cu and CuO nanoparticles were observed and have been elaborately discussed in this paper. In addition, the detailed growth kinematics of nanoparticles involved in the process of laser ablation technique have been highlighted.
关键词： high fluence,Cu–CuO,laser ablation,morphology
更新于2025-09-19 17:13:59
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Picosecond laser ablation and depth profile of Cu(In, Ga)Se2 thin film layer
摘要： Laser ablation based on picosecond laser was used to achieve the micro-analysis of Cu(In, Ga)Se2 (CIGS) thin film with the ablation crater diameter of 50 μm and the ablation crater central depth of 93 ± 13 nm. We achieved the depth profile of CIGS thin film with different laser shot number. The evolutions of spectral lines intensities of Ca from glass substrate and Ga and In from CIGS thin film layer, and intensity ratios of Ca/Ga and Ca/In could exhibit the change of the ablation volume, which could estimate the thin film thickness of single CIGS thin film layer. The average plasma temperature was calculated to be about 5243 ± 100 K, and the average electron density was calculated to be about 4.5×1016 cm?3. It is shown that our experimental setup is suitable to achieve a precise control and monitor the element compositions in each CIGS thin film layer in the research and in the production of CIGS solar cells.
关键词： Ablation morphology,Electron density,Cu(In, Ga)Se2 thin film,Picosecond laser induced breakdown spectroscopy,Plasma temperature
更新于2025-09-16 10:30:52