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N-Type Heavy Doping with Ultralow Resistivity in Ge by Sb Deposition and Pulsed Laser Melting
摘要： The fabrication of highly doped and high quality Ge layers is a challenging and hot topic for advancements in nanoelectronics, photonics and radiation detectors. In this article, we report on a simple method for junction formation consisting in sputter depositing or evaporating a thin pure Sb layer on Ge followed by cycles of Pulsed Laser Melting (PLM). We show that PLM promotes an efficient diffusion of high Sb concentrations into the melted Ge subsurface layer, followed by a fast epitaxial regrowth. The resulting layer is perfectly pseudomorphic to the Ge substrate, preserving the high strain level induced by the Sb, having covalent radius higher than Ge. In addition, it shows extremely high active concentrations up to 3x1020 cm-3 and a record low resistivity of 1.4x10-4 Ohm cm. The carrier mobility is also in line with the extrapolation of literature data with no signs of mobility degradation. Furthermore, infrared reflectivity confirms the good optical quality of the doped layers and demonstrates, for the first time, plasma wavelengths in Ge below 3 μm. These results are highly relevant for nanolectronic and plasmonic applications.
关键词： Plasmonics,Laser processing,Doping,Germanium,Antimony
更新于2025-09-16 10:30:52
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A bibliometric analysis for the research on laser processing based on Web of Science
摘要： Laser processing technology is one of the most important technologies in the 21st century and is becoming an area of great potential in manufacturing. There is an increase in the quality and quantity of publications related to this topic. To formally illustrate the research status of laser processing at a global level, the bibliometric analysis was used based on Web of Science database; 3958 documents were retrieved and countries or regions, institutions, journals, authors, research areas, author keywords, and highly cited articles were discussed in detail, respectively. Results show that China is the dominant country in this field, followed by the USA and Germany. Greece has the most collaborated articles, and Germany was the most active country that cooperated with another 19 countries or regions, especially with the USA, France, and China. Applied Surface Science is the most productive journal with the highest influence factor, and the University of California System has the highest h-index. “Material science, Multidisciplinary” is the most attractive area, with 1777 documents involved in it. In addition, the major hot topics concluded by author keywords are “laser processing,” “micro-structure,” and “thin film.” Finally, “intelligent laser processing” and “production scheduling” are given as the potential research hotspot in the near future.
关键词： production scheduling,h-index,Web of Science,bibliometric,laser processing
更新于2025-09-16 10:30:52
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Microstructure evolution in yttria stabilized zirconia during laser hybrid induction modification
摘要： To minimize crack susceptibility, a laser hybrid induction modification (LHIM) technique, involving the lowest laser energy required for continuously remelting at a preset inducting heating temperature, was used to partially remelt atmospheric plasma spraying (APS) yttria stabilized zirconia (YSZ) coating. Computational fluid dynamics (CFD) simulations indicate that a combination of elevated preheating temperature and low laser energy is essential to lower the cooling rate and temperature gradient and increase the solidification rate of melt pool. This is consistent with the experimental results obtained by eliminating the undesirable monoclinic phase and achieving the desired columnar and equiaxed grains. More importantly, the intersplat pores are healed to a higher degree, and the APS coatings become denser. These obvious structural changes decrease the differential shrinkage rate, mainly responsible for the initiation of cracks existing between the remelted layer and residual APS coatings during laser thermal shock. The healing of intersplat pores is also helpful for achieving less interfacial imperfections in the expansion of molten pool, thus developing a well-bonded remelted layer. Thus, a significantly decreased mismatch strain resulting from the lower thermal gradient and reduced differential shrinkage rate produces an acceptably low stress level for the crack susceptibility of remelted coating. Instead, the stress relief related to splat sliding is beneficial to achieve enlarged intercolumn gaps with high strain tolerance.
关键词： Computer simulations,Microstructure,Thermodynamic properties,Coating materials,Laser processing
更新于2025-09-16 10:30:52
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A cognitive approach for quality assessment in laser welding
摘要： Quality assessment in laser welding is of outmost importance. A plethora of in-line inspection techniques have been developed identifying melt pool geometry and weld defects for quality evaluation. This paper aims to introduce a cognitive assessment method for the prediction of weld quality and classification into different quality categories. The study corresponds to camera-based monitoring approaches utilizing thermal images obtained from process simulation models where artificial defects were inserted. A dimensionality reduction technique is deployed, and an image processing technique is afterwards implemented to identify weld defects based on specific melt pool features. A classification algorithm has also been developed and validated.
关键词： Laser processing,Defects recognition,Cognitive control,Quality assessment
更新于2025-09-16 10:30:52
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Influence of processing parameters on characteristics of laser-induced periodic surface structures on steel and titanium
摘要： Laser-induced periodic surface structures (LIPSS) can appear due to interaction between polarized laser pulses and surface. They can be used to improve or change the surface functionality. Here, titanium and steel surfaces were irradiated by linearly polarized, 30-ps-laser pulses (wavelength of λ=1064 nm) and 45-ns-laser pulses (wavelength of λ=1060 nm), respectively. We investigated how pulse fluence, number of pulses, and pre-existing defects influence LIPSS formation and period. The results show that fluences lower than single-pulse fluence threshold for ablation lead to LIPSS with periods within 150-500 nm, while increased fluence results in larger spatial period between 800-1100 nm. A slight change in processing parameters can also result in different topographical and/or chemical characteristics of the top surface layer, making LIPSS undetectable by SEM.
关键词： laser nanostructuring,laser surface engineering,LIPSS,laser processing
更新于2025-09-12 10:27:22
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Analysis of the laser drilling process for pilot holes in complex shaped components
摘要： In contrast to mechanical drilling, laser drilling can be applied directly to complex surfaces. The laser holes can thereby serve as pilot holes for mechanical deep hole drilling to produce high quality bore holes. This article examines the influence of pulse power, pulse duration and focus distance on the laser drilling process for curved surfaces using a Nd:YAG-Laser for the stainless steel X2CrNiMo17-12-2 and the case hardening steel 20MnCr5. By varying the laser parameters holes were produced that met the requirements for pilot holes in terms of diameter tolerances, drilling depth, conicity and material influences to enable the process combination.
关键词： process combination,laser processing,manufacturing technology,laser drilling,laser assisted processes
更新于2025-09-12 10:27:22
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Surface structuring of Kapton polyimide with femtosecond and picosecond IR laser pulses
摘要： Pulsed laser ablation is one of the most efficient and clean methods for high-precision processing and modification of polymers and biomaterials. Polymer ablation has been extensively investigated with ultraviolet lasers while little attention has been given to the infrared (IR) region, which becomes particularly interesting with the recent advances in ultrashort laser technologies. Here, we report the results of a comparative study on 1030-nm ultrashort laser structuring of Kapton polyimide, a polymer important in a variety of applications, with direct comparison of 247-fs and 7-ps laser pulses. The laser-induced damage thresholds for both pulse durations have been determined and the femtosecond laser threshold has been found to be considerably lower than that for picosecond pulses (by a factor of ～ 3.5). Both femtosecond and picosecond laser–produced craters have been thoroughly investigated as a function of pulse energy and focusing conditions. It has been demonstrated that femtosecond laser pulses enable accurate polyimide structuring while picosecond irradiation regimes result in a number of undesired effects such as re-deposition of the ablation debris, surface swelling, and the formation of high rims around the ablation craters. The mechanisms of polyimide ablation with femtosecond and picosecond IR laser pulses are discussed.
关键词： crater profile,swelling,laser ablation,damage threshold,laser processing,ultrashort laser pulses,multiphoton absorption,polymers,polyimide
更新于2025-09-12 10:27:22
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Microstructural and Metallurgical Assessment of the Laser-Patterned Cemented Tungsten Carbide (WC-CoNi)
摘要： Cemented carbide is difficult to machine using traditional chip-removal methods due to its hardness. Electrical discharge machining (EDM) is the common method applied to shape cemented carbides because high geometric precision can be achieved. However, some important defects (pores, residual stresses or oxidation products) can be induced due to thermal reactions. Ultra-short pulse laser processing can also provide high precision and meanwhile effectively avoid these defects due to its short laser-matter reaction time. In this paper, three different patterns on WC-CoNi cemented carbides for tribological purposes, namely line-like patterns, dimples and grooves, have been created using different laser set-ups with pulse duration in the range of nanoseconds (10-9s), picoseconds (10-12s) and femtoseconds (10-15s). Microstructural and metallurgical changes of modified surfaces have been studied. Laser scanning microscopy (LSM) is conducted to measure the pattern dimensions. Focused ion beam (FIB) in combination with scanning electron microscope (SEM) is used to investigate the microstructural changes of the patterned materials.
关键词： Surface integrity,Laser surface patterning (LST),Cemented carbide,Ultra-short pulse laser processing
更新于2025-09-12 10:27:22
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Laser radiation impact on a solid surface and formation of micro- and nanostructures
摘要： The work is devoted to the problem of micro- and nanostructuring of the surface of solids as a result of exposure to laser radiation. The method of forming periodic surface structures by means of femtosecond laser processing is presented using the example of solving the problem of titanium structuring.
关键词： femtosecond laser processing,micro- and nanostructures,laser radiation,titanium structuring
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Faster Femtosecond Laser Processing using a Dual-Focus SLM Emulated Lens
摘要： The generation of multiple beams is an established method to increase the processing speed of advanced laser-based material processing techniques. This multi-foci approach has shown promising results in laser micromachining, scanning microscopy, optical data storage, or optical tweezer arrays. Of particular interest is its application to manufacturing bigger objects where laser treatment is required over surfaces on the centimetre scale or larger. Using a Spatial Light Modulator (SLM), such parallelisation has been studied over the last few years by splitting the input beam into multiple beams (up to 1000 beams [1]) for simultaneous machining on a plane perpendicular to the propagation axis. This method is primarily based on holographic femtosecond laser processing [2] where computer-generated holograms (CGH) are displayed on an SLM. Further applications include phase distortion and lens aberration correction [3], or for four-dimension light shaping [4]. The SLM provides unique features for dynamic pulse shaping, more efficient use of the laser energy, or the machining of complex shapes.
关键词： spatial light modulator,laser micromachining,computer-generated holograms,dual-focus SLM,femtosecond laser processing
更新于2025-09-12 10:27:22