Showing papers on "Pulsed laser deposition published in 2012"
TL;DR: In this article, the state of the art on scientific and technologic locks, which have to be opened to consider direct atmospheric pressure plasma-enhanced chemical vapor deposition (AP-PECVD) a viable option for industrial application, is established.
Abstract: Over the last ten years, expansion of atmospheric pressure plasma solutions for surface treatment of materials has been remarkable, however direct plasma technology for thin film deposition needs still great effort. The objective of this paper is to establish the state of the art on scientific and technologic locks, which have to be opened to consider direct atmospheric pressure plasma-enhanced chemical vapor deposition (AP-PECVD) a viable option for industrial application. Basic scientific principles to understand and optimize an AP-PECVD process are summarized. Laboratory reactor configurations are reviewed. Reference points for the design and use of AP-PECVD reactors according to the desired thin film properties are given. Finally, solutions to avoid powder formation and to increase the thin film growth rate are discussed.
282 citations
TL;DR: In this article, angle resolved X-ray photoelectron spectroscopy and nanoprobe Auger electron spectrographs were used to identify the surface cation content, chemical bonding environment, and the spatial heterogeneities with nanoscale resolution.
Abstract: La0.6Sr0.4CoO3−δ(LSC) thin film cathodes synthesized by pulsed laser deposition at 450°C (LSC_450°C) and 650°C (LSC_650°C) exhibit different electrochemical performance. The origin of the differences in the oxygen reduction activity and stability of these cathodes is investigated on the basis of their surface chemistry and their surface atomic and electronic structures. Angle resolved X-ray photoelectron spectroscopy and nanoprobe Auger electron spectroscopy are used to identify the surface cation content, chemical bonding environment, and the spatial heterogeneities with nanoscale resolution. The higher electrochemical activity of LSC_450°C is attributed to the more stoichiometric cation content on the surface and the more uniform lateral and depth distribution of constituent cations. The poorly crystalline atomic structure of the LSC_450°C was found to prohibit the extensive segregation and phase separation on the surface because of the more favorable elastic and electrostatic interactions of Sr in the ...
272 citations
TL;DR: Growth of nm-thick yttrium iron garnet films and ferromagnetic resonance (FMR) linewidth properties in the films were reported in this article, where films were grown on gadolinium gallium garnet substrates by pulsed laser deposition (PLD).
Abstract: Growth of nm-thick yttrium iron garnet films and ferromagnetic resonance (FMR) linewidth properties in the films are reported. The films were grown on gadolinium gallium garnet substrates by pulsed laser deposition (PLD). Films in the 5–35 nm thickness range showed a (111) orientation and a surface roughness between 0.1 and 0.3 nm. The 10 nm films showed a 10 GHz FMR linewidth of about 6 Oe and a damping constant of 3.2 × 10−4. The FMR linewidth increases with both the surface roughness and the surface Fe deficiency. Thicker films exhibit a smaller FMR linewidth and a lower damping constant.
261 citations
TL;DR: In this paper, the authors present a review of the features distinguishing HiPIMS from other deposition methods along with how they influence the deposition conditions, such as the plasma parameters and the sputtered material, as well as the resulting thin film properties.
Abstract: High-power impulse magnetron sputtering (HiPIMS) is a promising sputtering-based ionized physical vapor deposition technique and is already making its way to industrial applications. The major difference between HiPIMS and conventional magnetron sputtering processes is the mode of operation. In HiPIMS the power is applied to the magnetron (target) in unipolar pulses at a low duty factor (<10%) and low frequency (<10 kHz) leading to peak target power densities of the order of several kilowatts per square centimeter while keeping the average target power density low enough to avoid magnetron overheating and target melting. These conditions result in the generation of a highly dense plasma discharge, where a large fraction of the sputtered material is ionized and thereby providing new and added means for the synthesis of tailor-made thin films. In this review, the features distinguishing HiPIMS from other deposition methods will be addressed in detail along with how they influence the deposition conditions, such as the plasma parameters and the sputtered material, as well as the resulting thin film properties, such as microstructure, phase formation, and chemical composition. General trends will be established in conjunction to industrially relevant material systems to present this emerging technology to the interested reader.
258 citations
TL;DR: In this paper, the introduction of effective artificial pinning centers into pulsed laser deposition derived Gd1Ba2Cu3O7−δ coated conductors has been studied with a view to improving the Ic-B-θ properties.
Abstract: The introduction of effective artificial pinning centers into pulsed laser deposition derived Gd1Ba2Cu3O7−δ coated conductors has been studied with a view to improving the Ic–B–θ properties. BaMOx (M = metal) was introduced into Gd1Ba2Cu3O7−δ film, with the expectation of forming fine nanorods such as BaZrO3 ones. BaHfO3 doped Gd1Ba2Cu3O7−δ coated conductors showed remarkably good Ic–B–θ characteristics, even at high temperature. A short sample with 1 µm film thickness prepared using a reel-to-reel system showed a minimum Ic value of 30 A/cm-w@77 K (A/cm-w@77 K to be read as ‘amps per centimeter width, at 77 K’) at 3 T. The minimum Jc value of ∼0.3 MA cm−2@77 K at 3 T was independent of the film thickness up to 2.9 µm. The 2.9 µm thick film showed a minimum Ic value of 84.8 A/cm-w@77 K at 3 T, corresponding to >200 A/cm-w@65 K at 5 T.
204 citations
TL;DR: To explain the transition from a core-shell configuration to a Janus configuration as a function of Ag quantity, density-functional theory calculations and atomistic molecular dynamics simulations are conducted to investigate the stability of this system.
Abstract: In order to determine the possibilities to control the chemical configuration of bimetallic nanoparticles, we have considered CuAg nanoparticles synthesized by a physical route as a model in this study. The synthesis was made by pulsed laser deposition under ultra-high vacuum conditions, via a sequential deposition procedure. We show that the temperature of the substrate and the absolute quantity of Ag in a particle are the main parameters that drive the chemical configuration. To explain the transition from a core–shell configuration to a Janus configuration as a function of Ag quantity, we have conducted density-functional theory calculations and atomistic molecular dynamics simulations to investigate the stability of this system. The results are presented together with the experimental observations.
152 citations
Patent•
16 Mar 2012TL;DR: In this paper, a writer main pole for a perpendicular magnetic recording system is provided, which has a tunable bottom gap to side gap ratio, and may be formed using deposition of a first seed layer through an ion beam deposition process, deposition of an intermediate non-magnetic gap layer through a chemical vapor deposition process.
Abstract: A writer main pole for a perpendicular magnetic recording system is provided. The writer pole has a tunable bottom gap to side gap ratio, and may be formed using deposition of a first seed layer through an ion beam deposition process, deposition of a second seed layer through a physical vapor deposition process, and deposition of a non-magnetic gap layer through a chemical vapor deposition process.
130 citations
TL;DR: In this article, the performance of CZTS thin films deposited by using pulsed laser deposition technique is investigated as a function of target composition, and the effect of the chemical composition in the precursor thin films on the structural, morphological, chemical and optical properties of the CZ TS thin films has been investigated.
126 citations
TL;DR: In this article, a pulsed laser deposition (PLD) method was used to enhance the electrochromic properties of anodically colored NiO thin films by growing them on FTO/glass substrates.
117 citations
TL;DR: In this article, the chemical composition of SrTiO3 thin films was characterized via X-ray photoelectron spectroscopy and Rutherford backscattering spectrometry, which revealed that deviations in laser fluence and deposition geometry can result in deviations of cation stoichiometry as large as a few percent.
Abstract: We report dramatic variations in cation stoichiometry in SrTiO3 thin films grown via pulsed laser deposition and the implications of this nonstoichiometry for structural, dielectric, and thermal properties. The chemical composition of SrTiO3 thin films was characterized via X-ray photoelectron spectroscopy and Rutherford backscattering spectrometry. These studies reveal that deviations in laser fluence and deposition geometry can result in deviations of cation stoichiometry as large as a few percent. Additionally, X-ray diffraction was used to probe structural evolution and revealed an asymmetric strain relaxation mechanism in which films possessing Sr-excess undergo relaxation before those possessing Sr-deficiency. Furthermore, the dielectric constant decreases and the loss tangent increases with increasing nonstoichiometry with intriguing differences between Sr-excess and -deficiency. Thermal conductivity is also found to be sensitive to nonstoichiometry, with Sr-excess and -deficiency resulting in 65% ...
111 citations
TL;DR: Thin films of polycrystalline cerium substituted yttrium iron garnet (CeYIG) were grown on an YIG seed layer on Si and Si-on-insulator substrates by pulsed laser deposition, and their optical and magneto-optical properties in the near-IR region were measured.
Abstract: Thin films of polycrystalline cerium substituted yttrium iron garnet (CeYIG) were grown on an yttrium iron garnet (YIG) seed layer on Si and Si-on-insulator substrates by pulsed laser deposition, and their optical and magneto-optical properties in the near-IR region were measured. A YIG seed layer of ~30 nm thick processed by rapid thermal anneal at 800°C provided a virtual substrate to promote crystallization of the CeYIG. The effect of the thermal budget of the YIG/CeYIG growth process on the film structure, magnetic and magnetooptical properties was determined.
TL;DR: By combining structural and chemical thin film analysis with detailed plume diagnostics and modeling of the laser plume dynamics, this article was able to elucidate the different physical mechanisms determining the stoichiometry of the complex oxides model material SrTiO3 during pulsed laser deposition.
Abstract: By combining structural and chemical thin film analysis with detailed plume diagnostics and modeling of the laser plume dynamics, we are able to elucidate the different physical mechanisms determining the stoichiometry of the complex oxides model material SrTiO3 during pulsed laser deposition. Deviations between thin film and target stoichiometry are basically a result of two effects, namely, incongruent ablation and preferential scattering of lighter ablated species during their motion towards the substrate in the O2 background gas. On the one hand, a progressive preferential ablation of the Ti species with increasing laser fluence leads to a regime of Ti-rich thin film growth at larger fluences. On the other hand, in the low laser fluence regime, a more effective scattering of the lighter Ti plume species results in Sr rich films.
TL;DR: A mechanism based on the reversible incorporation of a passivating SrO surface phase into the LSCrM lattice is proposed to explain the observed activation/deactivation process.
Abstract: Mixed-conducting perovskite-type electrodes which are used as cathodes in solid oxide fuel cells (SOFCs) exhibit pronounced performance improvement after cathodic polarization. The current in situ study addresses the mechanism of this activation process which is still unknown. We chose the new perovskite-type material La0.75Sr0.25Cr0.5Mn0.5O3±δ which is a potential candidate for use in symmetrical solid oxide fuel cells (SFCs). We prepared La0.75Sr0.25Cr0.5Mn0.5O3±δ thin film model electrodes on YSZ (111) single crystals by pulsed laser deposition (PLD). Impedance spectroscopy (EIS) measurements show that the kinetics of these electrodes can be drastically improved by applying a cathodic potential. To understand the origin of the enhanced electrocatalytic activity the surfaces of operating LSCrM electrodes were studied in situ (at low pressure) with spatially resolving X-ray photoelectron spectroscopy (μ-ESCA, SPEM) and quasi static secondary ion mass spectrometry (ToF-SIMS) after applying different electrical potentials in the SIMS chamber. We observed that the electrode surfaces which were annealed at 600 °C are enriched significantly in strontium. Subsequent cathodic polarization decreases the strontium surface concentration while anodic polarization increases the strontium accumulation at the electrode surface. We propose a mechanism based on the reversible incorporation of a passivating SrO surface phase into the LSCrM lattice to explain the observed activation/deactivation process.
TL;DR: In this paper, the structural, optical and etching properties of grown gallium oxide films were investigated in terms of high resolution X-ray diffraction, optical transmittance, atomic force microscopy, and Xray photoelectron spectroscopy.
TL;DR: In this article, the performance of Co3O4 NPs assembled thin coating catalyst was compared with homogenous catalyst producing Co+2 ions in methylene blue solution under visible light irradiation, and the effect of H2O2 concentration and effect of pH variation on dye degradation rate has been reported.
Abstract: Cobalt oxide (Co3O4) nanoparticles (NPs) assembled coating have been prepared by reactive pulsed laser deposition of Co, in O2 atmosphere, on Si or glass substrate ranging from room temperature to 250 °C The NPs, having narrow size distribution with average values of around 25–50 nm, were characterized by Raman, X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy The Co3O4 NPs synthesized at 150 °C comprise a mixed amorphous–nanocrystalline phase (that is unique property for catalysis) while complete crystallization of Co3O4 occurs at 250 °C with formation of spinel structure Photocatalytic properties of Co3O4 NPs assembled coating for degradation of methylene blue solution under visible light irradiation are reported The effect of H2O2 concentration and effect of pH variation on dye degradation rate has been reported The reusability of the Co3O4 NPs assembled thin coating catalyst was further evaluated in several recycling runs The activity of heterogeneous Co3O4 NPs assembled thin coating catalyst was compared with homogenous catalyst producing Co+2 ions in methylene blue solution
TL;DR: In this article, it was found that vanadium-doped amorphous MnO x films did significantly increase the specific capacitance at high CV scan rate as compared with the undoped MnOx films and increased linearly with the V atomic percentage.
TL;DR: In this paper, the vibrational modes observed in amorphous Ge-Sb-Te films are attributed, apart from defective octahedral coordination, to GeTe 4− n Ge n ( n ǫ = 1, 2, eventually 0) corner-and/or edge-sharing tetrahedra and SbTe 3 pyramidal entities, the latter dominated Raman spectra of all the films containing Sb 2 Te 3.
TL;DR: In this article, the magnetic hysteresis of BiFeO3/CoFe2O4 (BFO/CFO) nanocomposites were grown on SrTiO3 by pulsed laser deposition using a combinatorial method in which Bi1.2FeOO3 and CoFeO4 targets are alternately ablated.
Abstract: BiFeO3/CoFe2O4 (BFO/CFO) nanocomposites were grown on SrTiO3 by pulsed laser deposition using a combinatorial method in which Bi1.2FeO3 and CoFe2O4 targets are alternately ablated. The films had the same vertically nanostructured morphology as thin films prepared by ablation of a single target, consisting of epitaxial CoFe2O4 pillars in a BiFeO3 matrix. In a series of samples synthesized with a compositional spread, the out-of-plane magnetic anisotropy and the out-of-plane compressive strain of the CoFe2O4 pillars increased with decreasing volume fraction, and the anisotropy agreed with the value predicted from the strain state and magnetoelastic coefficients of CoFe2O4. These results show the dominant effect of magnetoelastic anisotropy in determining the magnetic hysteresis of the nanocomposite.
TL;DR: In this article, structural, morphological, magnetic and optical properties of nickel ferrite thin films having different thickness are reported, and the results are explained on the basis of anisotropy induced by cation inversion and strain.
Abstract: In the present work, structural, morphological, magnetic and optical properties of nickel ferrite thin films having different thickness are reported. All the films were deposited on Si (100) substrate by pulsed laser deposition technique. Thicknesses of the films determined by x-ray reflectivity vary from 62 to 176nm as the deposition time varies from 16 min to 40 min. The films were characterised by x-ray diffractogram, Fourier transform infrared (FTIR) and Raman spectroscopy for structural and phase confirmation. FTIR and Raman spectra confirm mixed spinel nature of nickel ferrite. Surface morphology is studied by Atomic force microscopy. All the films have granular nature. Magnetic properties were studied by vibrating sample magnetometer and magnetic hysteresis curves were recorded for all the films at room temperature and at10K. At 10K, saturation magnetisation was found to increase while coercivity deceases with thickness. The results are explained on the basis of anisotropy induced by cation inversion and strain. Optical properties were studied by UV-vis reflectance spectra. The value of optical band gap (5.7eV) was found to be independent of thickness of the film. Copyright © 2011 VBRI press.
TL;DR: In this paper, magneto-transport studies of topological insulator Bi-Te-3 thin films grown by pulsed laser deposition are presented. And the authors demonstrate that the strong linear-like MR at high field can be well understood as the weak antilocalization phenomena described by Hikami-Larkin-Nagaoka theory.
Abstract: We report magneto-transport studies of topological insulator Bi_{2}Te_{3} thin films grown by pulsed laser deposition. A non-saturating linear-like magneto-resistance (MR) is observed at low temperatures in the magnetic field range from a few Tesla up to 60 Tesla. We demonstrate that the strong linear-like MR at high field can be well understood as the weak antilocalization phenomena described by Hikami-Larkin-Nagaoka theory. Our analysis suggests that in our system, a topological insulator, the elastic scattering time can be longer than the spin-orbit scattering time. We briefly discuss our results in the context of Dirac Fermion physics and 'quantum linear magnetoresistance'.
TL;DR: In this paper, the authors report on the ultrafast optical limiting in the IR regime of pulse laser deposited VO 2 nanostructures, which is characterized by a significant and reversible variation of the refractive index under either thermal stimuli or by photo-induction.
TL;DR: In this article, two types of NiO-Li2CO3 nanocomposite electrodes have been prepared for the electrochemical decomposition studies, and the results showed that the NiO phase does not change significantly after charging process and may act as catalyst for the Li 2CO3 decomposition.
TL;DR: Electrochemical impedance spectroscopy (EIS) and secondary ion mass spectroscope (SIMS) measurements showed that for these samples the interfacial conductivity has a negligible effect on the transport properties.
Abstract: Biaxially textured epitaxial thin-film heterostructures of ceria and 8 mol % yttria-stabilized zirconia (8YSZ) were grown using pulsed laser deposition (PLD) with the aim to unravel the effect of the interfacial conductivity on the charge transport properties. Five different samples were fabricated, keeping the total thickness constant (300 nm), but with a different number of heterointerfaces (between 4 and 60). To remove any potential contribution of the deposition substrate to the total conductivity, the heterostructures were grown on (001)-oriented MgO single-crystalline wafers. Layers free of high-angle grain boundaries and with low density of misfit dislocations were obtained, as revealed by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM) analysis. The crystallographic quality of these samples allowed the investigation of their conduction properties, suppressing any transport effects along grain boundaries and/or interfacial dislocation pathways. Electrochemical impedance spectroscopy (EIS) and secondary ion mass spectroscopy (SIMS) measurements showed that for these samples the interfacial conductivity has a negligible effect on the transport properties.
TL;DR: In this article, a single-stage fabrication process is presented for the graphene fabrication based on the pulsed laser ablation of graphite target inside the cryogenic liquid using the pulsing nanosecond Q-switched Nd:Y3Al5O12 (Nd: YAG) laser at 1064 nm.
Abstract: In this work, a novel technique is presented for the graphene fabrication based on the pulsed laser ablation of graphite target inside the cryogenic liquid using the pulsed nanosecond Q-switched Nd:Y3Al5O12 (Nd:YAG) laser at 1064 nm. Single-stage fabrication process is taken into account as a remarkable advantage without need to high vacuum devices and additional chemical components. The synthesis process is controllable by changing the laser properties and the irradiation conditions accompanying easy collection of the products.
TL;DR: In this article, the impact of electrode architecture on the electrochemical reaction impedance for hydrogen oxidation was investigated by impedance spectroscopy under H2-H2O-Ar atmospheres in the temperature regime 450-650 °C.
Abstract: Highly porous oxide structures are of significant importance for a wide variety of applications in fuel cells, chemical sensors, and catalysis, due to their high surface-to-volume ratio, gas permeability, and possible unique chemical or catalytic properties. Here we fabricated and characterized Sm0.2Ce0.8O1.9−δ films with highly porous and vertically oriented morphology as a high performance solid oxide fuel cell anode as well as a model system for exploring the impact of electrode architecture on the electrochemical reaction impedance for hydrogen oxidation. Films are grown on single crystal YSZ substrates by means of pulsed laser deposition. Resulting structures are examined by SEM and BET, and are robust up to post-deposition processing temperatures as high as 900 °C. Electrochemical properties are investigated by impedance spectroscopy under H2–H2O–Ar atmospheres in the temperature regime 450–650 °C. Quantitative connections between architecture and reaction impedance and the role of ceria nanostructuring for achieving enhanced electrode activity are presented. At 650 °C, pH2O = 0.02 atm, and pH2 = 0.98 atm, the interfacial reaction resistance attains an unprecedented value of 0.21 to 0.23 Ω cm2 for porous films 4.40 μm in thickness.
TL;DR: In this article, a spinel NiCo2O4 was grown on a single crystalline MgAl 2O4 (001) substrates by pulsed laser deposition and magnetization measurement revealed hysteresis loops consistent with the reported ferrimagnetic order.
Abstract: We have grown epitaxial thin films of spinel NiCo2O4 on single crystalline MgAl2O4 (001) substrates by pulsed laser deposition. Magnetization measurement revealed hysteresis loops consistent with the reported ferrimagnetic order. The electrical transport exhibits a metallic behavior with the lowest resistivity of 0.8 mΩ cm and a metal insulator transition around the Neel temperature. The systematic variation in the properties of the films grown at different growth temperatures indicates a close relationship between the magnetic order and electrical transport.
TL;DR: In this article, As2Se3 glass films using spin coating from ethylenediamine solutions are characterized as a function of annealing conditions, which partially recovers the As-Se3 pyramid structure and brings the film refractive indices close to the bulk value.
Abstract: Thin film selenide glasses have emerged as an important material for integrated photonics due to its high refractive index, mid-IR transparency and high non-linear optical indices. We prepared high-quality As2Se3 glass films using spin coating from ethylenediamine solutions. The physio-chemical properties of the films are characterized as a function of annealing conditions. Compared to bulk glasses, as-deposited films possess a distinctively different network structure due to presence of Se-Se homo-polar bonds and residual solvent. Annealing partially recovers the As-Se3 pyramid structure and brings the film refractive indices close to the bulk value. Optical loss in the films measured at 1550 nm wavelength is 9 dB/cm, which was attributed to N-H bond absorption from residual solvent.
TL;DR: Structural phase transitions after thermal annealing of films deposited at RT and 200°C are confirmed and it is found that electron-phonon interaction is a function of temperature and particle size and is independent of the structure.
Abstract: Nanotwin structures are observed in high-resolution transmission electron microscopy studies of cubic phase CdS quantum dots in powder form by chemical co-precipitation method. The deposition of thin films of nanocrystalline CdS is carried out on silicon, glass, and TEM grids keeping the substrates at room temperature (RT) and 200°C by pulsed laser ablation. These films are then subjected to thermal annealing at different temperatures. Glancing angle X-ray diffraction results confirm structural phase transitions after thermal annealing of films deposited at RT and 200°C. The variation of average particle size and ratio of intensities in Raman peaks I2LO/I1LO with annealing temperature are studied. It is found that electron-phonon interaction is a function of temperature and particle size and is independent of the structure. Besides Raman modes LO, 2LO and 3LO of CdS at approximately 302, 603, and 903 cm−1 respectively, two extra Raman modes at approximately 390 and 690 cm−1 are studied for the first time. The green and orange emissions observed in photoluminescence are correlated with phase transition.
TL;DR: In this paper, the stabilization of magnetic glassy state in non-stoichiometric nickel ferrite thin films prepared by pulse laser deposition was reported and details of electronic structure of the films were presented and compared with stoichiometric bulk counterpart.
Abstract: We report stabilization of magnetic glassy state in non-stoichiometric nickel ferrite thin films prepared by pulse laser deposition. Details of electronic structure of the films are presented and compared with stoichiometric bulk counterpart. Hard x-ray photoelectron spectroscopy shows significant amount of oxygen vacancies and enhanced cationic inversion for thin films. Films show spin glass (SG) features which is contrary to the usual ferrimagnetic response of the bulk nickel ferrite. Films exhibit spin freezing temperature which is above room temperature in low fields (0.1 T) and shifts to lower temperature (∼250 K) in the presence of a large applied field of 3 T. An exceptionally large exchange bias (EB) of 170 Oe at a significantly higher temperature (∼50 K) is measured in cooling field of 3 T. In comparison, bulk samples do not show exchange bias and magnetic irreversibility vanishes in significantly weaker fields (i.e., few kOe). Role of oxygen vacancies is to induce spin canting by destabilizing i...
TL;DR: In this article, Al-doped ZnO (AZO) thin films were grown by Pulsed Laser Deposition at room temperature in oxygen atmosphere, and the O 2 pressure was varied from 0.01 to 10