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Synthesis of heavy fermion CeCoIn5 thin film via pulsed laser deposition
摘要： CeCoIn5 (Co115) thin films have been grown on Al2O3 (000l) substrates through the pulsed laser deposition (PLD). The films are grown mainly along the c-axis, with CeIn3 and In-related alloys. The rock-salt type grains are nucleated, where Co115 grains mixed with excess indium are evenly distributed over the substrate. The electrical resistivity of the films shows a Kondo coherence peak near 47 K and the zero-resistance superconducting state at 1.8 K, which is the first observation in the PLD grown thin films of Co115. The Rietveld refinement of the thin films shows that the c/a ratio (tetragonality) is suppressed to 1.6312 from 1.6374 of single crystals, which is consistent with the linear relationship between the superconducting transition temperature and tetragonality. The good agreement indicates that the PLD could provide an alternative route to tune the 2D character of the critical spin fluctuations to understand the superconducting pairing mechanism of Co115.
关键词： Metal thin film,CeCoIn5 thin film,Heavy fermions,Superconductivity,Pulsed laser deposition
更新于2025-09-12 10:27:22
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High transmittance Er-doped ZnO thin films as electrodes for organic light-emitting diodes
摘要： Rare earth element-Erbium (Er) doped ZnO (ErZO) thin films were deposited on glass substrates by pulsed laser deposition (PLD). The effect of the Er doping concentration on photoelectric properties of ErZO thin films was investigated in the range of 0–2.0 wt. %. The Er doping resulted in the improvement of n-type conductivity as compared with intrinsic ZnO thin films. The optimized ErZO thin films present the low resistivity of 3.4 (cid:2) 10(cid:3)4 X/cm, high carrier concentration of 5.9 (cid:2) 1020/cm3, and high visible optical transmittance ((cid:4)93%) when the Er content is 1.0 wt. %. The ErZO thin films were used as transparent anodes to fabricate organic light-emitting diodes (OLEDs). Impressively, with ErZO as the anode, the current efficiency of the OLED device can reach as high as 86.5 cd/A, which was increased by 14% when compared with the reference OLED device (76.0 cd/A) using indium tin oxide as the anode.
关键词： Er-doped ZnO,transparent conducting oxides,pulsed laser deposition,thin films,organic light-emitting diodes
更新于2025-09-12 10:27:22
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Optical characterization of low temperature amorphous MoOX, WOX, and VOX prepared by pulsed laser deposition
摘要： Transition metal oxides are materials combining properties of electrical conductivity, optical transparency, and catalytical function. They are widely used in applications including solar cells, flat panel displays, and detectors. In particular, high work function oxides such as MoO3, WO3, and V2O5 have become popular. In many applications, low deposition temperatures are required, leading to amorphous structure. In this study, thin films of amorphous MoOX, WOX, and VOX were prepared by pulsed laser deposition, and their optical properties and work function were determined. Samples of polycrystalline ZnO were also prepared for comparison. Substrate temperature was varied in the range of 25 °C – 100 °C and oxygen pressure was varied in the range of 10 – 20 Pa during the process and also during the following sample cool-down and chamber venting. Optical characterization was based on photothermal deflection spectroscopy, which is a non-contact and non-destructive method for measuring directly absorptance spectra with sensitivity down to 10–4. Absorptance in the band gap serves as an indication of the presence of defects such as oxygen vacancies or metallic phases. Our optimized films achieved a sub-bandgap absorption coefficient as low as 103 cm-1 for MoOX, VOX, and 102 cm-1 in the case of the WOX. From the gradient of the absorption edge, Urbach energy was obtained, evaluating disorder in the semiconductor material. The work function of each material was obtained by Kelvin probe, and a slight correlation with Urbach energy was found. X-ray photoelectron spectroscopy indicated successful stochiometric transfer mainly for the lowest pressure and highest temperature samples.
关键词： work function,Urbach energy,optical spectroscopy,pulsed laser deposition,transparent metal oxide,photothermal deflection spectroscopy
更新于2025-09-12 10:27:22
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Morphological design of complex oxides during pulsed-laser deposition: The role of plasma-plume expansion
摘要： Complex oxides such as tin-doped indium oxide (ITO) are widely utilized as transparent conductors in a variety of functional devices. Typically, they are fabricated by sputtering, which often requires additional annealing to achieve high transparency and conductivity. Using pulsed laser deposition (PLD), both high transparency and high conductivity have been achieved without annealing, using instead selected gas species and pressures. However, the relative roles of Stranski-Krastanov-like and vapor-liquid-solid (VLS) growth modes during morphological transitions remain controversial. Here, we report on PLD of ITO in an inert-gas environment, identifying the role of plasma-plume expansion in the selection of VLS vs vapor-solid (VS) growth. For the lowest N2 pressure, indium-tin droplet formation, followed by self-catalyzed VLS growth, is observed. With increasing N2 pressure, a transition from VLS to VS growth is apparent. It is hypothesized that oxygen scattering at the lowest N2 pressure induces a metal-rich plume, which leads to metal droplet formation, followed by VLS growth. As the N2 pressure is increased, the plasma-plume and its metal-rich core are compressed, resulting in a transition to VS growth. This tunable compression of the plasma-plume o?ers a route to the morphological design of a wide range of functional complex oxide devices with tunable optical and electronic performance.
关键词： plasma-plume expansion,morphological design,VLS growth,pulsed laser deposition,complex oxides,VS growth
更新于2025-09-12 10:27:22
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Ionic liquid/ZnO(0001?) single crystal and epitaxial film interfaces studied through a combination of electrochemical measurements and a pulsed laser deposition process under vacuum
摘要： O-Polar ZnO(000%1) single crystals and ZnO and Mg-doped ZnO (MgZnO) films which were subsequently deposited on the ZnO crystals by a pulsed laser deposition (PLD) method were electrochemically investigated through the interfaces with ionic liquid (IL) in a vacuum. The sample surfaces were confirmed to be atomically clean and flat by reflection high energy electron diffraction (RHEED) observation, prior to their electrochemical measurements. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were then performed, and the donor density, flat band potential of these ZnO samples, and the electric double layer capacitance at the IL/ZnO interfaces were successfully evaluated. The flat band potentials of ZnO and MgZnO films were found to shift to more negative potentials relative to those of the single crystal ZnO, with different values for thicker films, respectively. Some possible origins of the different flat band potentials between ZnO and MgZnO films, and their film thickness dependence of the flat band potential will be discussed in this paper.
关键词： vacuum,ZnO,flat band potential,pulsed laser deposition,MgZnO,electric double layer capacitance,ionic liquid,electrochemical measurements
更新于2025-09-12 10:27:22
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Mechanistic insights into the phenomena of increasing capacity with cycle number: using pulsed-laser deposited MoO <sub/>2</sub> thin film electrodes
摘要： Lithium ion batteries typically lose capacity or energy storage density (i.e. capacity fading) over the course of extended cycling which can be problematic for applications and appears to be exaggerated when high current rates are used. However, in some cases fluctuations in capacity with cycle number and even increases in capacity with cycle number are noted with predominantly thin film based electrodes. Here we demonstrate the synthesis and in-depth characterisation of laser deposited MoO2 thin film anodes and its unconventional mechanism. A MoO2 electrode shows an initial capacity of 79 mA h g?1 which increases to capacities of 600 mA h g?1 at 15.8 A g?1 after 90 000 cycles. A maximum capacity of 1714 mA h g?1 was achieved in an electrode cycled at 1.5 A g?1 for over 3800 cycles, the highest recorded capacity in MoOx anodes to date. The most intriguing aspects of this work is the fact that capacity is shown to fluctuate and typically increase well above the theoretical capacity of MoO2. A combination of electrochemical cycling, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, focused ion beam milling and transmission electron microscopy at various states of cycling is used to illustrate a proposed mechanism. The mechanism illustrated is based on exfoliation of layers of MoO2 off the pulsed laser deposition (PLD) grown MoO2 electrodes during cycling that creates additional surface area and easier access for Li-ions to both adsorb to the surface and insert/react with the host material. Further features in the capacity evolution are rationalised by this mechanism and methods to control the capacity evolution are detailed. These results present a rational explanation for when an electrode undergoes a substantial increase in capacity over its extended cycling life.
关键词： pulsed laser deposition,MoO2 thin film anodes,exfoliation mechanism,Lithium ion batteries,capacity increase
更新于2025-09-12 10:27:22
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Pulsed laser deposited Cr-doped CoFe2O4 thin film as highly efficient oxygen evolution reaction electrode
摘要： Traditional powder OER catalysts have many disadvantages such as the extremely complicated electrode preparation process. Herein, squama-like Co0.95Cr0.05Fe2O4 thin film electrode is directly deposited on flexible Ni foam substrate by a novel method of pulsed laser deposition. Cr doping leads to the electrode highly effective for OER, and the current density is about 2.1 times of that compared with undoped CoFe2O4 thin film at 1.8 V. The Co0.95Cr0.05Fe2O4 thin film exhibits an overpotential of 293.3 mV at 10 mA/cm2 as well as extraordinary stability, which is far better than that of CoFe2O4 thin film and no-load Ni foam.
关键词： Thin films,Pulsed laser deposition,Electron microscopy,Oxygen evolution reaction
更新于2025-09-12 10:27:22
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Chemical Structure of EVA Films Obtained by Pulsed Electron Beam and Pulse Laser Ablation
摘要： Poly(ethylene-co-vinyl acetate) (EVA) films were deposited for the first time using physical methods. The chemical structure of the films obtained using two techniques, pulsed electron beam deposition (PED) and pulsed laser deposition (PLD), was studied by attenuated total reflection Fourier infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). Whilst significant molecular degradation of the EVA films was observed for the PLD method, the original macromolecular structure was only partially degraded when the PED technique was used, emphasizing the superiority of the PED method over PLD for structurally complex polymers such as EVA. Optical and scanning electron microscopic observations revealed compact and smooth EVA films deposited by pulsed electron beam ablation as opposed to heterogeneous films with many different sized particulates obtained by PLD.
关键词： chemical structure analysis,poly(ethylene-co-vinyl acetate),pulsed laser deposition,pulsed electron beam deposition
更新于2025-09-11 14:15:04
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Applications of Laser Ablation - Thin Film Deposition, Nanomaterial Synthesis and Surface Modification || Concurrent Multi-Target Laser Ablation for Making Nano-Composite Films
摘要： New method of using laser ablation for film deposition that can be called as concurrent multi-beam multi-target matrix-assisted pulsed laser evaporation and pulsed laser deposition (MBMT-MAPLE/PLD) is described. Practical MBMT-MAPLE/PLD system built at Dillard University has three separate laser beams, three targets and the remotely controlled plume overlapping mechanism that provides even mixing of the target materials during their deposition on the substrate. The system accommodates MAPLE targets in the form of polymer solutions frozen with flowing liquid nitrogen. The feasibility of the method was demonstrated when it was used for making polymer nano-composite films with two inorganic additives: upconversion fluorescent phosphor NaYF4:Yb3+, Er3+ and aluminum-doped ZnO (AZO). Three laser beams, an infrared 1064-nm beam for the MAPLE and two 532-nm beams for the PLD targets, were concurrently used in the process. The fabricated nano-composite films were characterized using X-ray diffraction, scanning electron microscopy (SEM), optical fluorescent spectroscopy, and the measurement of the quantum efficiency (QE) of the upconversion fluorescence. The size of the inorganic nanoparticles varied in the range 10–200 nm. The AZO additive increased QE by 1.6 times. The conclusion was made on the feasibility of MBMT-MAPLE/PLD method for making multi-component nano-composite films for various applications.
关键词： matrix-assisted pulsed laser evaporation,polymer nano-composite films,pulsed laser deposition,laser ablation
更新于2025-09-11 14:15:04
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Impact of lattice defects on water oxidation properties in SnNb <sub/>2</sub> O <sub/>6</sub> photoanode prepared by pulsed-laser deposition method
摘要： SnNb2O6 is one of the promising photoanode materials for photoelectrochemical water splitting. We prepared the SnNb2O6 thin-film photoanode with various Sn/Nb ratios by a pulsed-laser deposition method and investigated impacts of lattice defects in the SnNb2O6 photoanode on the water oxidation property. Photoelectrochemical measurements and Raman spectroscopy analyses for the SnNb2O6 photoanodes presented that the water oxidation property can be improved by suppressing the formation of the acceptor site caused by the substitution of Sn4+ for the Nb5+ site in the crystal lattice of SnNb2O6. This study provides material’s design strategy based on defect chemistry to realize an efficient SnNb2O6 photoanode used for the photoelectrochemical cell, which can operate without an external bias.
关键词： lattice defects,photoanode,water oxidation,pulsed-laser deposition,SnNb2O6
更新于2025-09-11 14:15:04