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New Approach for Pulsed-Laser Testing That Mimics Heavy-Ion Charge Deposition Profiles
摘要： A novel approach for two-photon absorption (TPA) pulsed-laser testing produces extended charge deposition profiles that are analogous to those produced by heavy ions. In this approach, which utilizes an axicon rather than a spherical lens, the conventional Gaussian beam is replaced by a quasi-Bessel beam. The key feature of a quasi-Bessel beam, relevant to pulsed-laser single-event effects (PL-SEE) studies, is that its radial size (~1 μm) remains constant over the axial length of the beam (several 100s of μm) resulting in a charge-deposition profile that more closely mimics that produced by a heavy ion. This elongated charge distribution directly lends itself to a simple and intuitive description in terms of linear-energy transfer, or LET, facilitating laser/ion correlation studies. Experimental results comparing a conventional TPA PL-SEE focusing geometry and the axicon focusing geometry are presented for three different test vehicles: a 45-nm SOI nFET, a bulk silicon photodiode, and an LM 124 operational amplifier. Using the axicon approach, strong laser/ion correlation is observed in the silicon photodiode for single-event transients (SET) across a wide range of LETs. The correlation is achieved by “tuning” the laser to the desired LET rather than relying on pre-existing heavy-ion data and therefore this approach holds promise as a predictive tool.
关键词： single-event effect (SEE),silicon,Correlation methods,single-event transient (SET),heavy-ion testing,pulsed-laser,two-photon absorption,linear energy transfer (LET)
更新于2025-09-12 10:27:22
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Nonlinear Optical Properties of Zinc Oxide Thin Films Produced by Pulsed Laser Deposition
摘要： In this work, the nonlinear optical properties of Zinc Oxide (ZnO) thin films produced on microscope slide glass substrates at room temperature (RT) using Pulsed Laser Deposition (PLD) method has been presented. PLD system consists of a vacuum chamber (pumped by a turbo molecular pump, backed with a rotary pump), rotating sample and substrate holders, optical thickness measurement system, infrared temperature measurement system and a nanosecond laser system. Previously deposition vacuum chamber evacuated down to ~10-8 mbar and deposition was taken place about 1.3×10-1 mbar oxygen background gas pressure value. Morphological properties of thin films were obtained by Atomic Force Microscopy (AFM) that shows homogenous and smooth film structure. Thin films crystallinity were investigated by using X-Ray Diffraction (XRD) method and showed that polycrystalline ZnO structure with the largest peak corresponding to (002) orientation but some films contain Zn with (101) orientation . The thicknesses of the films were deduced from reflectance measurement using a fitting software and crosschecked with profilometer and AFM measurements. The thickness of the films ranged between 10 nm and 220 nm. Linear optical properties were obtained by using UV-VIS Spectrometer. Furthermore, we presented the nonlinear optical properties of the ZnO thin films that were obtained by the z-scan method.
关键词： Z-scan system,Zinc Oxide Thin Film,Nonlinear Optical Properties,Pulsed Laser Deposition
更新于2025-09-12 10:27:22
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - THz Properties of Fe and Ti Oxides Nanoparticles Obtained by Pulsed Laser Ablation
摘要： We present Dielectric properties of Fe and Ti oxides nanoparticles (NPs) measured by THz-TDS. The NPs were obtained via ns pulsed laser ablation (PLA) of the metals in air and water and were annealed at different temperatures. In the paper, we exhibit the dependence of absorption spectra on NPs structure: from magnetite to hematite for Fe, and from anatase to rutile for Ti. The prospects for their use as materials for the THz photonics are discussed.
关键词： THz-TDS,Fe and Ti oxides nanoparticles,THz photonics,dielectric properties,pulsed laser ablation
更新于2025-09-12 10:27:22
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The effects of the oxygen content on the photoelectrochemical properties of LaFeO3 perovskite thin films obtained by pulsed laser deposition
摘要： The physical properties of perovskite oxides are strongly influenced by their stoichiometry and one of the key features of these materials is the tunability of their functionality by controlling the interplay between the compositional and structural properties. Here, the effects on the photoelectrochemical (PEC) water splitting properties of ferroelectric LaFeO3 thin films obtained at different oxygen partial pressures during growth are reported in conjunction with the morphological, optical and structural features. The LaFeO3 thin films have been deposited by pulsed laser deposition on Nb:SrTiO3 substrates. The strong dependence of the photocurrent values Jphoto on the growth conditions is revealed by the photoelectrochemical measurements. Strong variations of the lateral coherence lengths L‖ of LaFeO3/Nb:SrTiO3 with the oxygen partial pressure values are noticed from the X-ray diffraction (XRD) analysis. All the films are heteroepitaxial with small tensile strain levels detected in the crystalline structure, but only for a narrow interval of oxygen partial pressures the LFO/STON thin films show high quality crystalline structure with large lateral coherence length L‖ and photoelectrochemical currents.
关键词： oxygen partial pressure,perovskite oxides,photoelectrochemical,pulsed laser deposition,water splitting
更新于2025-09-12 10:27:22
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Laser‐Ablation Produced Cobalt‐Nickel Phosphate with High‐ValenceNickel Ions as Active Catalyst for Oxygen Evolution Reaction
摘要： Cost-effective, highly efficient and stable non-noble metal-based catalysts for oxygen evolution reaction (OER) are very crucial on energy storage and conversion. Here, we report an amorphous cobalt-nickel phosphate (CoNiPO4) containing considerable amount of high-valence Ni3+ specie as an efficient electrocatalyst for OER in alkaline solution. The catalyst was converted from Co-doped Ni2P through pulsed laser ablation in liquid (PLAL) and exhibits a large specific surface area of 162.5 m2/g and a low overpotential of 238 mV at 10 mA/cm2 with a Tafel slope of 46 mV/dec, being much lower than those of commercial RuO2 and IrO2. Our work demonstrates that PLAL is a powerful technology for generating amorphous CoNiPO4 with high-valence Ni3+, thus paving a new way towards highly effective OER catalysts.
关键词： OER,high valence state,cobalt-nickel phosphate,Pulsed laser ablation in liquid
更新于2025-09-12 10:27:22
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Microstructure development in Pulsed Laser Welding of Dual Phase Steel to Aluminium Alloy
摘要： Lap joining of aluminium 6061 and dual phase (DP 600) steel was carried out in pulse welding mode using a high power diode laser. The effect of laser parameters (laser power, scanning speed and pulse duration) on the microstructural evolution during conduction welding was studied. The large difference in thermal and physical properties of DP 600 and Al 6061 alloy results in the formation of brittle intermetallic phases along the interface of the weld zone. At a laser power of 4 kW, scanning speed of 5 mm/s and pulse duration of 10 ms the thickness of the intermetallic phase formed was found to be reduced i.e. in the range of 1- 7 μm. The porosity in the weld zone were mainly due to the entrapment of the zinc vapors during welding because of its low vaporization temperature compared to DP 600 and Al 6061 alloy. Microstructural characterization of the intermetallic phases was done using scanning electron microscopy, X-ray diffraction and the phase composition were characterized using energy dispersive spectroscopy. The micro-hardness testing was to evaluate the mechanical properties of the lap joint. A maximum hardness of 461 HV was observed along the weld- aluminium interface owing to the presence of hard and brittle Fe2Al5 and FeAl3 intermetallic phases.
关键词： Dual phase steel,Intermetallic phases,Pulsed laser welding,Aluminium alloys
更新于2025-09-12 10:27:22
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Effective size separation of laser-generated, surfactant-free nanoparticles by continuous centrifugation
摘要： High-power, nanosecond, pulsed-laser ablation in liquids enables the continuous synthesis of highly-pure colloidal nanoparticles (NPs) at an application-relevant scale. The gained mass-weighted particle size distribution is however often reported to be broad, requiring post treatment like centrifugation to remove undesired particle size fractions. To date, available centrifugation techniques are generally discontinuous, limiting the throughput and hindering economic upscaling. Hence, throughout this paper, a scalable, continuously operating centrifugation of laser-generated platinum nanoparticles in a tubular bowl centrifuge is reported for the first time. To that end, using a 121 W ns-laser, a continuous production of a colloidal suspension of NPs, yet with broad particle size distribution has been employed, yielding productivities of 1 - 2 g/h for gold, silver, and platinum. Subsequent downstream systematic study of relevant centrifugation parameters involved, effective size optimization and respective size sharpness parameters for a maximum Pt nanoparticle diameter of 10 nm are reported. The results of the experimental centrifugation of laser-generated Pt-NPs were in excellent agreement with the theoretically-calculated cut-off diameter. After centrifugation with optimized parameters, the polydispersity indices of the Pt-NPs size distributions were reduced by a factor of six and higher monodispersities were observed.
关键词： continuous process chain,tubular bowl centrifugation,contamination-free nanoparticle processing,Pt-NPs,pulsed laser ablation in liquids
更新于2025-09-12 10:27:22
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Simulation of the dynamics of heat accumulation during in-volume modification with ultrashort laser pulses
摘要： Working with ultrashort pulsed (USP) laser systems with high repetition rates, heat accumulation effects evolve and subsequently the absorption becomes linear. As a consequence, the process dynamics change significantly. Structuring glasses with those USP Lasers leads to melted lines that are used for waveguides, welding or selective laser-induced etching whose resulting qualities are strongly depending of the structuring results and given smoothness. We perform simulations during in-volume modification processes, by recalculating the absorption behavior in between the iteration steps of heat accumulation. The simulation results provide explanations for smoothness or non-smoothness of modifications comparable to experiments in glass.
关键词： pulse-to-pulse simulation,heat accumulation,iterative simulation,high repetition ultrashort pulsed laser,in-volume modification,simulation of process dynamics
更新于2025-09-12 10:27:22
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Pulsed-laser-deposited lead sulfide nanoparticles based decoration of porous silicon layer as an effective passivation treatment for multicrystalline silicon
摘要： We report on the use of pulsed laser deposition (PLD) of PbS nanoparticles (PbS-NPs) on porous silicon layers in order to passivate multicrystalline silicon (mc-Si) substrates intended for solar cells applications. The porous silicon (PS) layer was first obtained through the electrochemical anodization of the mc-Si substrate, and then the PLD technique was used to decorate the PS layer by PbS-NPs at room temperature. By varying the number of laser ablation pulses (NLP) from 50 to 1200, the average size of the PbS-NPs was varied from ~2 nm to ~10 nm. The X-ray diffraction analysis has confirmed the crystalline quality of the PbS-NPs, whereas the transmission electron microscopy observations showed the uniform decoration of the PS by the PbS-NPs. By combining different characterization techniques, we were able to identify NLP = 200 as the optimal decoration condition that leads to the best passivation, in terms of the lowest surface reflectivity (of 15% at 500 nm wavelength), the highest PL intensity of the PS layer (centered around 633 nm) and the longest minority carrier lifetime (as long as ~430 μs versus 40 μs for the bare treated PS layer and 2.2 μs for the untreated bare mc-Si).
关键词： Pulsed laser deposition,Porous silicon,Solar cells,PbS nanoparticles,Surface passivation
更新于2025-09-12 10:27:22
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Laser formation of thin-film memristor structures based on vanadium dioxide
摘要： The thin films of VO2 and the metal-oxide-metal (MOM)-structures of Au/VO2/VO2-x/Au based on them, which are promising for the use in neuromorphic electronic devices, have been obtained by the method of pulsed laser drop-free deposition on the c-sapphire substrates at room temperature. Using the cyclic I-V characteristics, a memristive effect has been revealed in the vertical geometry of the Au/VO2/VO2-x/Au MOM-structures. The x value was varied in the course of their growth by changing the pressure of buffer oxygen from 0.1 to 40 mTorr in the vacuum chamber, which provided the needed conductivity in the depleted injection layer. The dependence of memristive properties on the thickness of the semiconductor layer and concentration of the oxygen vacancies has been established. The oxygen pressure in the PLD method has been determined, at which the volatile behavior of the memristor resistive switching starts to appear at an oxide region thickness of 10/30 nm.
关键词： memristor,VO2,pulsed laser deposition,neuromorphic electronic devices,resistive switching
更新于2025-09-12 10:27:22