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Investigations in the fabrication of surface patterns for wettability modification on a Zr-based bulk metallic glass by nanosecond laser surface texturing
摘要： Laser texturing has previously been employed to enhance the wettability of metallic alloys. Such studies reported that modifying the wettability of a surface is a result of changes in both its topography and its chemistry. In this paper, an investigation about laser-induced surface wettability modification is also reported but for a less studied type of material in this context. In particular, nanosecond (ns) laser processing was employed to texture two types of surface patterns, i.e. dimples and grooves, on the surface of a Zr-based bulk metallic glass (BMG) known as Vitreloy 105. The specific focus of the research was on understanding the role played by both surface topography and chemistry modifications in changing the wettability of the original surface. Using static contact angle measurements, it was found that groove patterns enhanced the hydrophilicity of the original BMG, while dimple patterns weakened it. Based on the obtained 3D surface measurements and XPS data, it is suggested that the reduced hydrophilicity of dimple-textured surfaces was driven by the decrease of hydrophilic C=O and O=C-O bonds post laser processing. While these bonds were also reduced for groove-textured patterns, the hydrophilicity was still enhanced following laser irradiation as a result of the dominant role that a much larger induced surface roughness should play in this case.
关键词： Surface topography,Bulk metallic glass,Nanosecond laser surface texturing,Surface chemistry.,Wettability
更新于2025-09-23 15:19:57
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Dopant Activation of In Situ Phosphorusa??Doped Silicon Using Multia??Pulse Nanosecond Laser Annealing
摘要： Nanosecond laser annealing was performed on ISPD silicon in single- and multi-pulse modes. the active phosphorus concentration was increased with the laser power density and number of laser pulses and more phosphorus was activated with nanosecond lasers than with millisecond lasers. Moreover, almost all the incorporated phosphorus atoms were activated by the nanosecond laser without major strain loss when ISPD silicon melt
关键词： phosphorus-doped silicon,nanosecond laser annealing,diffusion,dopant activation,strain
更新于2025-09-23 15:19:57
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Pulsed laser annealing of spray casted Cu(In,Ga)Se2 nanocrystal thin films for solar cell application
摘要： We report ambient processing of 2.5 μm thick layers of Cu(In,Ga)Se2 (CIGS) nanocrystals thin films sprayed on CdS/i:ZnO/Al:ZnO/Soda lime glass substrates with pulsed laser annealing (PLA), using 1064 nm laser at 220 ns pulse width for solar cell fabrication. The choice of the nanosecond pulse width of the near-infrared laser source is critical for the effectiveness of the laser sintering of the CIGS layer irrespective of substrate thermal stability. Solid state sintering by PLA post treatment is evidenced via morphological and structural analysis. The analysis confirms the improvement in the quality of CIGS absorber with respect to its grain size from 5 nm to 20 nm after PLA, which is expected to reduce deep level defects. The short circuit current density of photovoltaic devices prepared using ambient processed laser annealed absorber layer increased significantly from 0.75 mA cm?2 to 8 mA cm?2, resulting in reasonable power conversion efficiency exceeding 1%. The promising results realized by PLA treatment, presented in this work, have great potential to be integrated into scalable roll-to-roll manufacturing of CIGS solar cells.
关键词： Non-vacuum,Cu(In,Ga)Se2,Solar cells,Annealing,Nanosecond,Laser
更新于2025-09-23 15:19:57
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Dynamic behavior modeling of laser-induced damage initiated by surface defects on KDP crystals under nanosecond laser irradiation
摘要： the issue of laser-induced damage of transparent dielectric optics has severely limited the development of high-power laser systems. exploring the transient dynamic behaviors of laser damage on KDp surface by developing multi-physics coupling dynamics model is an important way to reveal the mechanism of nanosecond laser damage. In this work, KDP crystals are taken as an example to explore the mechanism of laser-induced surface damage. Based on the theories of electromagnetic field, heat conduction and fluid dynamics, a multi-physics coupling dynamics model is established for describing the evolution of nanosecond damage processes. The dynamics of laser energy transmission, thermal field distribution and damage morphology during nanosecond laser irradiation are simulated with this model. it is found that the enhancement of light intensity caused by surface defect plays an important role in the initial energy deposition and damage initiation of the laser irradiation area. The evolution of temperature field and crater morphology during subsequent laser irradiation is helpful to understand the laser damage process. The feasibility of this model is verified by the morphology information of typical defect-induced laser damage. this work provides further insights in explaining the laser-induced damage by surface defects on KDp crystals. the model can be also applied to investigate the laser damage mechanisms of other transparent dielectric optics.
关键词： laser-induced damage,multi-physics coupling model,nanosecond laser irradiation,KDP crystals,surface defects
更新于2025-09-19 17:13:59
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Groove Formation in Glass Substrate by a UV Nanosecond Laser
摘要： This study reports the laser grooving of glass. In this study, an ultraviolet (UV) nanosecond laser is used to produce grooves in soda lime glass by varying laser power, scan speed, pulse repetition rate, and number of scans. The threshold power density to generate damage on glass surface is found to be ~6.37 × 108 W/cm2. According to the result of a single laser scan, at a high laser power and low scan speed, material removal does not nearly occur, and only volume melting underneath the glass surface and large thermal crack are induced. With the decreasing laser power and increasing scan speed, a groove with a smooth surface is formed owing to the melting-dominant material removal process. The groove of rough surface morphology is produced with the further increase of the scan speed due to shattering induced by shock wave. Under this condition, it is found that either small cracks are produced or a crack-free groove is obtained. In this study, the fabrication of the microchannel for bio-chip application is also attempted by multiple laser scans. The near rectangular-shaped and crack-free groove (width × depth: ~220 μm × ~500 μm) with quite a smooth surface is fabricated by the multiple laser scans with a non-zero scan spacing.
关键词： ultra violet (UV),laser grooving,nanosecond laser,glass,groove
更新于2025-09-19 17:13:59
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Wetting angle stability of steel surface structures after laser treatment
摘要： In this work, we have used a nanosecond pulsed fiber laser to modify the wettability characteristics of AISI 430 steel. For this, various surface morphologies were created on the samples by laser irradiation with different overlapping and intensity parameters. Immediately upon laser treatment, all the structured samples acquired either hydrophilic or superhydrophilic wetting angles. All the samples were also analyzed with XRD. Then, laser-treated samples were kept in ambient air and/or low-temperature annealing was applied to reach hydrophobic surface properties. Interestingly, these surfaces returned back practically to their initial wetting state by cleaning in an ultrasonic bath. The obtained results are analyzed based on the existing wettability models.
关键词： Nanosecond laser structuring,Hydrophobic and hydrophilic surfaces,Wettability transition,Wetting angle stability
更新于2025-09-19 17:13:59
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Nanosecond laser writing of straight and curved waveguides in silicon with shaped beams
摘要： The authors demonstrate a method for transverse writing of optical waveguides in a crystalline silicon wafer using a nanosecond laser with a shaped beam profile that is formed by a pair of cylindrical lenses. In contrast to traditional writing methods, this method avoids forming asymmetric waveguide profiles. Both straight and curved waveguides are written with a nearly circular transverse guide profile and are found to support single-mode propagation for 1550 nm wavelength light. The propagation loss for this wavelength is also measured.
关键词： nanosecond laser,waveguide,silicon,beam shaping
更新于2025-09-19 17:13:59
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Ablation behavior of SiCp/AA2024 composites irradiated by a single-pulse nanosecond laser
摘要： In this study, homogenous Al alloy and SiC materials and SiCp/AA2024 composites with mean particle diameters of 5 μm and 30 μm were irradiated by a single-pulse nanosecond fiber laser with a 200 ns pulse width and 1064 nm wavelength. Using a laser pulse, regular circular heat-affected zones (HAZ) were formed in the homogenous materials. For the composites, an Al allloy matrix was melted and sputtered, and the SiC particles bulged when irradiated by the laser pulse. According to the measured results, the HAZ increased with the pulse energy density in a logarithmic pattern. Nonlinear fitting results demonstrated that the damage thresholds of the composites and SiC homogenous materials were the lowest and highest, respectively. SiCp/AA2024 composites with different mean particle diameters exhibited similar damage thresholds. The measured etching depths of the SiC particles and Al alloy matrix were smaller than the respective values of the homogenous materials. Thermal simulation results revealed that thermal-mechanical coupling occurred between the SiC particles and Al alloy matrix. The SiC particles in the composite heated more rapidly under a nanosecond laser, and the heat was then transferred to the matrix. Large SiC particles constrained the matrix’s molten pool, which accelerated its gasification but hindered further etching.
关键词： Composites materials,Phase transitions,Ablation mechanism,Nanosecond laser irradiating,Interface effect
更新于2025-09-19 17:13:59
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Segregation and activation of Sb implanted in Si by UV nanosecond-laser-anneal-induced non-equilibrium solidification
摘要： In advanced logic devices, access resistance to transistors is dominated by metal–semiconductor contact resistivity. Recent studies report values below 1 × 10?9 ohm cm2, realizing metastable incorporation of dopants into epitaxially grown semiconductor materials. In this study, we have investigated segregation and activation of antimony (Sb) implanted in silicon (Si) epilayers by using UV nanosecond pulsed laser annealing (LA). The Sb-implanted Si epilayers were partially or fully molten by LA, followed by the analysis of atomic and electrically active dopant concentrations as well as the observation of surface morphology evolution. To discuss the impact of the solute trapping phenomenon on substitutional incorporation of the Sb atoms, we also simulated the evolution of solidification front velocity in the LA-induced non-equilibrium solidification. It is noteworthy that the active level of the Sb atoms largely surpasses their reported equilibrium solubility limit (～2.6 × 1020 at./cm3 compared to ～6.8 × 1019 at./cm3) when the non-equilibrium solidification approaches a near-complete solute trapping regime.
关键词： activation,Si,UV nanosecond-laser-anneal-induced,non-equilibrium solidification,Segregation,Sb implanted
更新于2025-09-19 17:13:59
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Dynamics of nanosecond-laser-induced melting of tin in vacuum, air, and water
摘要： Tin with its low melting point and vapor pressure is a good model material to investigate laser ablation mechanisms under various ambient conditions. Here we measured the nanosecond-laser-induced damage thresholds of tin in vacuum, air, and water. The threshold fluence is found to be ~ 0.1 J/cm2 regardless of the environment unlike more refractory metals when threshold values in water are considerably higher than those in air. Analysis of the morphology and chemical composition of the irradiated surface as well as numerical simulations of tin laser heating demonstrate that the observed surface modification is due to melting but not oxidation. For the case of water environment, the conductive heat transfer to water is found to play only a minor role in tin heating and melting. The simulations show also that the formation of a water vapor layer near the tin surface occurs at a considerably higher fluence, above 0.15 J/cm2, and thus the surface damage is not affected by scattering of the incident laser light by the vapor–liquid interface, typical for more refractory metals. Peculiarities of laser ablation of low-melt materials in liquids and nanoparticle formation are discussed.
关键词： Nanosecond laser,Laser ablation,Water vaporization,Nanoparticle formation,Melting,Tin
更新于2025-09-16 10:30:52