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Uniform and smooth molybdenum film produced through picosecond pulsed laser deposition
摘要： An approach to achieve uniform and smooth molybdenum (Mo) ?lm on a BK7 glass plate at room temperature is proposed through picosecond pulsed laser deposition, with the pulsed laser radiating the target along a linear track. A numerical model is established to analyze the in?uence of linear scanning offsets on the thickness homogeneity of the deposited thin ?lm. Through an appropriate choice of radiation intensity and scanning parameters, a uniform and smooth layer of Mo thin ?lm is prepared with its maximum thickness variation and root-mean-square roughness better than 5% and 1.2 nm, respectively.
关键词： picosecond pulsed laser deposition,smooth,numerical model,molybdenum film,uniform
更新于2025-09-11 14:15:04
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Structural, Spectroscopic, and Excitonic Dynamic Characterization in Atomically Thin Yb <sup>3+</sup> ‐Doped MoS <sub/>2</sub> , Fabricated by Femtosecond Pulsed Laser Deposition
摘要： The large area deposition and synthesis of 10 mm × 10 mm atomically thin Yb3+-doped MoS2 films by femtosecond pulsed laser deposition on a silica glass optical platform for device applications are demonstrated for the first time. The presence of Yb3+-ion doping is confirmed using photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The Yb3+-doped MoS2 films, when excited with a 976 nm laser, exhibit room temperature PL with a peak at 1002 nm. The XPS and Raman spectroscopic analyses of the Yb3+-doped and undoped films show that the deposited films are a mixture of 2H- and 1T-MoS2 after postdeposition annealing at 500 °C. The density functional theory analysis shows that the 1T phase is metastable by +77 kJ (≈0.8 eV) mol-1, when compared with the 2H state at 0 K. Ultrafast transient nonlinear optical spectroscopic measurements prove that the saturable absorption of undoped MoS2 is significantly modified after Yb3+-ion doping, by displaying dopant-host structure charge transfer. The complex transient absorption line shape shows a combination of bleach (negative) signals at the A (670 nm) and B (630 nm) exciton energies, and a strong induced absorption below the A exciton level. The results presented herein provide critical insight in designing novel rare-earth-ion doped 2D materials and devices.
关键词： molybdenum disulfide,femtosecond pulsed laser deposition,saturable absorber,rare-earth ion photoluminescence,nonlinear optical properties
更新于2025-09-11 14:15:04
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Manganese oxide nanofoam prepared by pulsed laser deposition for high performance supercapacitor electrodes
摘要： Manganese oxide nanofoam has been prepared by pulsed laser deposition, from a metallic Mn target in a 5 Torr pressure O2 buffer atmosphere. The as-prepared samples were heat-treated at different temperatures (300?C-500?C) in air. Both as-deposited and heat-treated samples have a high porosity foam-like morphology, as shown by Field Emission Scanning Electron Microscopy. High Resolution Transmission Electron Microscopy revealed that the nanofoam is composed by linked nanoparticles with slight crystallization and growth of the nanoparticles due to heat-treatment, which was confirmed by X-ray diffraction, Raman Spectroscopy and X-ray Photoelectron Spectroscopy. These techniques also showed a variable oxide composition upon heat treatment. The supercapacitive properties of manganese oxide nanofoam treated at 300?C exhibited a specific capacitance higher than 1000 F/g, in the 0 to +1.0 V potential range. After heat treatment at 400?C and 500?C, the specific capacitance decreased compared to that of the 300?C treated sample. An increase of about 130% in the initial capacitance was obtained after 500 cycles for this sample. However, it decreases to one third of the maximum value after 5000 cycles. The results shows that the obtained manganese oxide nanofoam has very high specific capacitance but need to improve the cycle stability.
关键词： microstructures,pulsed laser deposition,porous materials,supercapacitors,nanofoam,manganese oxides
更新于2025-09-11 14:15:04
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Pulsed laser deposition with rapid beam deflection by a galvanometer mirror scanner
摘要： A pulsed laser deposition system with rapid beam deflection (RBD-PLD) by a galvanometer mirror scanner has been developed for alternating ablation of multiple targets with a single laser instrument. In this system, the alternating deposition of different target materials is carried out by scanning the laser beam between the positionally fixed targets with a galvanometer mirror instead of mechanically switching the target positions on a fixed optical path of the laser beam as is done in conventional pulsed laser deposition (PLD) systems. Thus, the “wait” time required for switching target materials to be deposited, which typically takes several seconds in a conventional system, can be made as short as a few milliseconds. We demonstrate some of the advantages of this PLD system in several technologically important aspects of thin film synthesis: (1) fast fabrication of binary alloy films, (2) preparation of natural composition spread libraries, (3) effect of the target switching time on the deposition of volatile compounds, (4) control of the degree of mixing of two different materials in a film, and (5) efficient growth of compositionally graded thin films.
关键词： galvanometer mirror scanner,rapid beam deflection,composition spread libraries,volatile compounds,pulsed laser deposition,thin film synthesis,compositionally graded thin films,binary alloy films
更新于2025-09-11 14:15:04
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Long-term stabilized high-density CuBi <sub/>2</sub> O <sub/>4</sub> /NiO heterostructure thin film photocathode grown by pulsed laser deposition
摘要： Harvesting sustainable hydrogen through water-splitting requires a durable photoelectrode to achieve high efficiency and long lifetime. Dense, uniform CuBi2O4/NiO thin film photocathodes grown by pulsed laser deposition achieved photocurrent density over 1.5 mA cm-2 at 0.4 VRHE and long-term chronoamperometric stability for over 8 hours.
关键词： heterostructure,pulsed laser deposition,water-splitting,CuBi2O4,NiO,hydrogen,photocathode
更新于2025-09-11 14:15:04
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Influence of different post-annealing temperatures on physical properties of La0.72Ca0.28MnO3:Ag0.2 thin films by pulsed laser deposition technique
摘要： La0.72Ca0.28MnO3:Ag0.2/LaAlO3 (100) thin ?lms, prepared by pulsed laser deposition, were post-annealed at di?erent temperatures in air. X-ray di?raction technique were used to analysize the orientation and lattice parameter, atomic force microscope (AFM) and scanning electronic microscope (SEM) were employed to characterize the surface morphology of the thin ?lms. Resistance vs. temperature (R-T) behaviors of the thin ?lms were tested with standard four-probe technique. The surface morphology results show that the grain size increases and crystalline quality of the ?lms are improved with increased annealing temperature up to 1200 °C, while the amount of grains also increases; R-T results illustrate that both the temperature coe?cient of resistance (TCR) and metal-insulator transition temperature (TMI) of the ?lms, increase with annealing temperature. In particular, TCR of thin ?lm (post-annealing at 1200 °C) reaches 28.8%·K?1, which makes such ?lms be promisingly applicated in thermal detectors near the room temperature.
关键词： Pulsed laser deposition technique,Electrical properties,La0.72Ca0.28MnO3:Ag0.2 thin ?lms,Surface morphology
更新于2025-09-11 14:15:04
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Ferroelectric/photoluminescence effect in Pr-doped (Bi0.5Na0.5)TiO3–BaTiO3 thin film fabricated by the pulsed laser deposition method
摘要： In this work, (100)-oriented Pr-doped (Bi0.5Na0.5)TiO3–BaTiO3 ferroelectric/photoluminescence film was fabricated on SrRuO3-electroded Pb(Mg1/3Nb2/3)O3–PbTiO3 single-crystal substrate. The phase structure, domain, ferroelectric, and photoluminescence performance were studied. Results indicated the Pr-BNBT thin film has pure phase structure, dense microstructure, and exhibited (100) orientation out of the plane. Well-defined ferroelectric hysteresis loop with the remanent polarization of ~ 18?μC/cm2 and obvious photoluminescence emission spectrum were obtained. Based on the piezoresponse force microscopy, the ferroelectric domain structure was characterized and the domain size was ~ 100?nm. The present ferroelectric/photoluminescence multifunctional thin film has potential for multifunctional MEMS actuator and optical devices.
关键词： Thin film,Pr-doped,Ferroelectric,Photoluminescence,Pulsed laser deposition
更新于2025-09-11 14:15:04
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Gyrotropic slab waveguide coupled silica microfiber-based magnetic field sensor
摘要： By controlling the polarization direction of BaTiO3 (BTO) layer, the nonvolatile and reversible resistive switching behavior of the BaTiO3/La0.7Sr0.3MnO3 (BTO/LSMO) layered heterostructure have been observed. Pulsed laser deposition (PLD) technique was used to prepare it on the (001) oriented single-crystal SrTiO3 (STO) substrate, and its magnetic and electric properties were studied. Moreover, the change of the resistivity and metal-insulator transition temperature (TMI) for the LSMO layer were found to be induced by the switching of the electric field direction. The resistivity is decreased while the TMI is increased for the accumulation state of hole carriers when a negative electric field is applied to the BTO layer. By contrast, the resistivity is increased while the TMI is decreased for the depletion state of hole carriers when a positive electric field is applied to the BTO layer. This result indicates a nonvolatile and reversible resistive switching behavior in the multiferroic heterostructure control through the external electric field on ferroelectric layer, which provides a platform to develop unique electronic devices, such as nonvolatile random-access memories, sensors and memristive devices, etc.
关键词： multiferroic heterostructure,resistive switching behavior,pulsed laser deposition,nonvolatile random-access memories
更新于2025-09-11 14:15:04
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Formation of poly-crystalline BaSi2 thin films by pulsed laser deposition for solar cell applications
摘要： A new growth method for BaSi2 thin films by using pulsed laser deposition (PLD) on transparent SiO2 and CaF2 substrates has been developed. X-ray diffraction and Raman spectroscopy revealed the poly-crystalline property of the deposited films. By introducing a thin Si buffer layer on SiO2 substrate, the crystalline quality of BaSi2 thin films were improved. BaSi2 thin films exhibited a Ba/Si ratio very close to 0.5, indicating the good stoichiometry control of PLD growth. The absorption coefficient of the poly-BaSi2 reached 105 cm-1 and its band gap was deduced to be 1.32 eV, which are similar to those grown by molecular beam epitaxy or sputtering. A maximum photoresponsivity of 12.5 mA/W was achieved in the BaSi2 thin film, which implies the potential of PLD-deposited BaSi2 for thin film solar cell applications.
关键词： Thin films,BaSi2,Solar energy materials,Pulsed laser deposition
更新于2025-09-11 14:15:04
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Bulk and surface characterisation of micrometer-thick cobalt ferrite films grown by IR PLD
摘要： We have studied micrometer-thick cobalt ferrite films deposited on Si (100) single crystal substrates by nanosecond pulsed laser deposition at 1064 nm.The thickness of the deposited films (1.3 μm) was monitored by AFM. The chemical and structural characterisation of the films was carried out by Raman spectroscopy and transmission M?ssbauer spectroscopy at 300 and 26 K. For comparison purposes, transmission M?ssbauer data at these two temperatures were also recorded from a commercial cobalt ferrite powder and the home-made target used to grow the films. The surface characterisation was performed by X-Ray Photoelectron Spectroscopy (XPS) and Integral Low Energy Electron Spectroscopy (ILEEMS). XPS showed Co and Fe to be present as Co2+ and Fe3+, as expected for cobalt ferrite. The Raman spectra showed the lines characteristic of cobalt ferrite. The M?ssbauer spectra, both in the transmission and backscattering modes, were fitted to two sextets whose hyperfine parameters are in good agreement with those expected from Fe3+ cations occupying the tetrahedral and octahedral sites in the spinel-related structure. No significant differences were observed in the relative areas of the two sextets in the transmission and ILEEMS spectra, suggesting that the cation distribution at the surface and the bulk are not too different. However, the relative areas of the two components changed drastically with temperature both in the spectra of the films as in those recorded from the cobalt ferrite standards. We discuss the possible origin of the evolution with temperature of those relative areas.
关键词： X-ray photoelectron spectroscopy,Raman spectroscopy,Cobalt ferrite,M?ssbauer spectroscopy,Pulsed laser deposition
更新于2025-09-10 09:29:36