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Effect of neutron irradiation on the structural, electrical and optical properties evolution of RPLD VO2 films
摘要： This study reports on the effect of neutron irradiation at different fluences on the properties of VO2 thin films. The irradiations were performed at NUR research reactor, Algiers at a temperature of about 40 °C, with fast neutron fluence (En > 1 MeV) up to 1.9 × 1018 n.cm?2. The induced defects have been investigated using structural, optical and electrical measurements. Both bulk sensitive characterization techniques, Raman and grazing incident angle X-ray diffraction (GIXRD) analysis, show that no structural transformation is induced by neutron irradiation, although strain induced defect production are generated throughout the films while surface sensitive techniques, X-ray photoelectron spectroscopy (XPS) and work function measurements, show that the charge carrier (electron) concentration at room temperature decreases after irradiation. Potentially due to fast neutron irradiation induced defects, mainly in the form of Frenkel pairs, swelling and color center formation occurs in VO2 thin films without amorphization. This is further corroborated by an increase of the room temperature resistivity through the irradiated films. Temperature-dependent electrical and optical transmission measurements confirm that the characteristic semiconductor-to-metal transition of the VO2 films is preserved upon irradiation. We therefore conclude that VO2 is an excellent candidate for thermal shielding and thermal management of small satellites.
关键词： Smart radiator device,Vanadium dioxide,Neutron irradiation,Phase transition,Pulsed laser deposition
更新于2025-09-19 17:15:36
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Tailoring Photoluminescence from Si-Based Nanocrystals Prepared by Pulsed Laser Ablation in He-N2 Gas Mixtures
摘要： Using methods of pulsed laser ablation from a silicon target in helium (He)-nitrogen (N2) gas mixtures maintained at reduced pressures (0.5–5 Torr), we fabricated substrate-supported silicon (Si) nanocrystal-based ?lms exhibiting a strong photoluminescence (PL) emission, which depended on the He/N2 ratio. We show that, in the case of ablation in pure He gas, Si nanocrystals exhibit PL bands centered in the “red - near infrared” (maximum at 760 nm) and “green” (centered at 550 nm) spectral regions, which can be attributed to quantum-con?ned excitonic states in small Si nanocrystals and to local electronic states in amorphous silicon suboxide (a-SiOx) coating, respectively, while the addition of N2 leads to the generation of an intense “green-yellow” PL band centered at 580 nm. The origin of the latter band is attributed to a radiative recombination in amorphous oxynitride (a-SiNxOy) coating of Si nanocrystals. PL transients of Si nanocrystals with SiOx and a-SiNxOy coatings demonstrate nonexponential decays in the micro- and submicrosecond time scales with rates depending on nitrogen content in the mixture. After milling by ultrasound and dispersing in water, Si nanocrystals can be used as e?cient non-toxic markers for bioimaging, while the observed spectral tailoring e?ect makes possible an adjustment of the PL emission of such markers to a concrete bioimaging task.
关键词： pulsed laser ablation in gases,pulsed laser deposition,silicon quantum dots,bioimaging,silicon nanoparticles,quantum con?nement,photoluminescence,silicon oxynitride
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 19th International Conference on Nanotechnology (IEEE-NANO) - Macao (2019.7.22-2019.7.26)] 2019 IEEE 19th International Conference on Nanotechnology (IEEE-NANO) - Pulsed Laser Deposited MoS <sub/>2</sub> for the Fabrication of MoS <sub/>2</sub> /Graphene Photodetector
摘要： Since the 21st century, with the continuous development of technology, much tremendous progress has been made in the microelectronics industry. When the channel of the device is reduced to the nanometer scale, the silicon-based semiconductor has approached its physical limit, and the performance begins to decrease, so the traditional silicon-based semiconductor industry has entered the research bottleneck. Compared with traditional silicon-based semiconductors, two-dimensional materials are increasingly used in the semiconductor industry due to their ultra-thin atomicity and semiconductor characteristics. As a typical representative of two-dimensional materials, MoS2 is widely used for device preparation, including gas sensors, phototransistors, flexible thin film transistors, lithium-ion battery electrodes and heterojunction diodes. However, achieving high-quality, controllable large-area preparation of MoS2 is still a major problem, which seriously hinders the development of MoS2 in the application field. In this paper, pulsed laser deposition is used to prepare large-sized MoS2 by controlling different deposition time.
关键词： Atomic layer deposition,MoS2,pulsed laser deposition
更新于2025-09-19 17:13:59
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Enhanced visible-light-photoconversion efficiency of TiO2 nanotubes decorated by pulsed laser deposited CoNi nanoparticles
摘要： The pulsed laser deposition (PLD) technique has been used to decorate TiO2 nanotubes (NTs) with cobalt-nickel (CoNi) nanoparticles (NPs). The TiO2 NTs were produced beforehand through the controlled anodic oxidation of titanium substrates. The effect of the nature of the PLD background gas (Vacuum, O2 and He) on the microstructure, composition and chemical bondings of the CoNi-NPs deposited onto the TiO2-NTs has been investigated. We found that the PLD CoNi-NPs have a core/shell (oxide/metal) structure when deposited under vacuum, while they are fully oxidized when deposited under O2. On the other hand, by varying the CoNi-NPs loading of the TiO2-NTs (through the increase of the number of laser ablation pulses (NLP)), we have systematically studied their photocatalytic effect by means of cyclic-voltammetry (CV) measurements under both AM1.5 simulated solar light and filtered visible light. We show that depositing CoNi-NPs on the substrate under vacuum and He increases the photo-electrochemical conversion effectiveness (PCE) by 600% (at NLP = 10,000) in the visible light domain, while their overall PCE degrades with NLP under solar illumination. In contrast, the fully oxidized CoNi-NPs (deposited under O2) are found to be the most effective catalyst under sunlight with an overall increase of more than 50% of the PCE at the optimum loading around NLP ~1000. Such catalytic enhancement is believed to result from both an enhanced light absorption by CoO (of which bandgap is of ~2.4 eV) and the formation of a heterojunction between NiO/CoO nanoparticles and TiO2 nanotubes.
关键词： TiO2 nanotubes,Pulsed laser deposition,Cobalt/nickel nanoparticles,Photo-electrochemistry,Water-splitting
更新于2025-09-19 17:13:59
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Preparation and deposition of Pr-Fe-B permanent magnet powder using pulsed laser
摘要： We have already prepared a thin permanent magnet with the thickness of sub millimeter by obtaining magnet powders using a PLD (Pulsed Laser Deposition) method. In the study, the PLD followed by a flash annealing enabled us to deposit isotropic Pr-Fe-B magnet powders with coercivity (Hcj) > 1000 kA/m on a stainless thin shaft applicable to a miniaturized motor. Observation on the surface of Pr-Fe-B magnets and evaluation on mechanical behavior was carried out. Since the surface of a Pr-Fe-B magnet was coated by a Pr oxide through an annealing process, their magnetic properties didn’t degrade after one year. We also confirmed that the Pr-Fe-B magnet has possibility to be applied to a micro magnetization process. It was clarified that the powder technology using the PLD is useful to propose a thin magnet applicable to a next generation small motor.
关键词： stainless shaft,coating,Pr-Fe-B permanent magnet powder,PLD (Pulsed Laser Deposition)
更新于2025-09-19 17:13:59
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Characterization of MgO/TiN bilayer deposited on cube-textured copper using pulsed-laser deposition technique
摘要： Here we demonstrate heteroepitaxial growth of MgO/TiN thin films on flexible metal foil of copper substrates using pulsed laser deposition. X-ray and electron diffraction measurements revealed that the epitaxial MgO/TiN bilayer was oriented along (002) direction. The large mismatch between TiN islands and Cu substrate was effectively reduced by the 5/6 and 6/7 variations of domains. Despite the local irregularity of misfit dislocations at TiN/Cu, the domain-matching epitaxy paradigm is a remarkably accurate theory. MgO/TiN bilayer is chemically homogeneous and Mg, Ti, or Cu atoms do not segregate into the low-angle grain boundaries regardless of MgO/TiN films thickness. Thus, it appears that thickness may be reduced up to the value in which TiN fully covers the rough surface of Cu tape. Unfortunately, issues related to the presence of in-plane TiN contraction, probably generated by the difference in thermal expansion coefficient, and the origin of misfit dislocations irregularity at TiN/Cu interface remain unresolved. Our findings can make a substantial contribution to further research on Cu-based coated conductors and help in better understanding the ways that MgO/TiN bilayer are grown on Cu tape.
关键词： titanium nitride,pulsed-laser deposition,magnesium oxide,copper,growth,epitaxy,domain-matching epitaxy
更新于2025-09-19 17:13:59
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Ferroelectric properties of gradient doped Y <sub/>2</sub> O <sub/>3</sub> :HfO <sub/>2</sub> thin films grown by pulsed laser deposition
摘要： A HfO2-based thin ?lm is a nanoscale ferroelectric material with a high-k dielectric and CMOS compatibility, which make it a promising candidate for high-performance electronics. Here, we demonstrate the synthesis of a ferroelectric Y-doped HfO2 (HYO) thin ?lm by pulsed laser deposition. This HYO thin ?lm is gradient doped by alternately depositing a HfO2 ceramic target and a Y2O3 ceramic target. In the ?lms, the orthorhombic phase, ferroelectric phase, is proved by grazing incidence x-ray diffraction and scanning transmission electron microscopy measurements. Moreover, the HYO thin ?lm embraces outstanding ferroelectric and dielectric properties, its remanent polarization is up to 10.5 lC/cm2, and the dielectric constant is 27. The 180(cid:2) inversion of the domain can be observed in a piezoelectric power microscopy image, while the phase contrast of the write domain fades with time. Therefore, this work provides a reliable approach to obtain a ferroelectric HYO thin ?lm, which enables great potential in future high-performance nanoelectronics.
关键词： pulsed laser deposition,Y-doped,ferroelectric,thin film,HfO2
更新于2025-09-19 17:13:59
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Self-assembly of a lateral quasi-Ohmic CuInSe <sub/>2</sub> /InSe isotype heterojunction for flexible devices by pulsed laser deposition
摘要： The contacts between two-dimensional InSe films and metal electrodes play an important role in nanoelectronics flexible devices. Generally, there is a large work function difference between the Au and InSe films, which would form a Schottky contact to deteriorate device performances. Herein, we designed a lateral self-assembled CuInSe2/InSe isotype heterojunction on a flexible mica substrate by pulsed laser deposition, which could improve the contact performances between electrodes and InSe films. By combining the X-ray photoelectron spectroscopy and Kelvin probe force microscopy results, the In rich CuInSe2 and InSe regions could act as quasi-n+-n junctions for reduction of the contact resistance with electrodes. Compared to the InSe films with Au electrodes, the CuInSe2/InSe isotype heterojunction presents approximately half channel resistance and four times photocurrent values. Moreover, the heterojunction devices can still maintain relatively good performance under bending states by restraining the dark current. The present work proves the potential of CuInSe2/InSe isotype heterojunctions for flexible applications.
关键词： pulsed laser deposition,flexible devices,isotype heterojunction,CuInSe2/InSe,quasi-Ohmic contact
更新于2025-09-19 17:13:59
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Comparative Study of the Structure, Composition, and Electrocatalytic Performance of Hydrogen Evolution in MoSx~2+?′/Mo and MoSx~3+?′ Films Obtained by Pulsed Laser Deposition
摘要： Systematic and in-depth studies of the structure, composition, and efficiency of hydrogen evolution reactions (HERs) on MoSx films, obtained by means of on- and off-axis pulsed laser deposition (PLD) from a MoS2 target, have been performed. The use of on-axis PLD (a standard configuration of PLD) in a buffer of Ar gas, with an optimal pressure, has allowed for the formation of porous hybrid films that consist of Mo particles which support a thin MoSx~2+δ (δ of ~0.7) film. The HER performance of MoSx~2+δ/Mo films increases with increased loading and reaches the highest value at a loading of ~240 μg/cm2. For off-axis PLD, the substrate was located along the axis of expansion of the laser plume and the film was formed via the deposition of the atomic component of the plume, which was scattered on Ar molecules. This made it possible to obtain homogeneous MoSx~3+δ (δ~0.8–1.1) films. The HER performances of these films reached saturation at a loading value of ~163 μg/cm2. The MoSx~3+δ films possessed higher catalytic activities in terms of the turnover frequency of their HERs. However, to achieve the current density of 10 mA/cm2, the lowest over voltages were ?162 mV and ?150 mV for the films obtained by off- and on-axis PLD, respectively. Measurements of electrochemical characteristics indicated that the differences in the achievable HER performances of these films could be caused by their unique morphological properties.
关键词： nanocatalysts,buffer gas,pulsed laser deposition,transition metal chalcogenides,hydrogen evolution reaction
更新于2025-09-19 17:13:59
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Pulsed laser deposition of antimony selenosulfide thin film for efficient solar cells
摘要： Antimony selenosul?de, Sb2(SxSe1(cid:2)x)3, has been considered as a promising light harvesting material for low-cost, non-toxic, and stable solar cell applications. However, current preparation methods of Sb2(SxSe1(cid:2)x)3 suffer from low-quality ?lms, which hampers the performance improvement in Sb2(SxSe1(cid:2)x)3-based solar cells. Herein, we develop a pulsed laser deposition technique to fabricate antimony selenosul?de ?lms with ?at and compact surface morphology and high crystallinity. The composition of the as-obtained ?lms can be conveniently tuned via varying molar ratios of Sb2S3 and Se in targets. At optimized conditions, we fabricate planar heterojunction solar cells and then obtain a signi?cantly improved power conversion ef?ciency of 7.05%. Our research offers a facile and robust preparation method for Sb2(SxSe1(cid:2)x)3 ?lms with enhanced photovoltaic properties.
关键词： antimony selenosulfide,photovoltaic properties,thin film,pulsed laser deposition,solar cells
更新于2025-09-19 17:13:59