PLD Method Research Articles

Double Columnar Interlayer for Increased Cathodic Activity of Intermediate Temperature Solid Oxide Fuel Cells

Effects of double columnar structure interlayer film, in which tensile strain were introduced, on cathodic activity of SmCoO3 was investigated. Double columnar film of Pr2NiO4(PNCG)-Sm doped CeO2 (SDC), PrBaCo2O5.5-SDC, Sm0.6Sr0.4CoO3(SSC)- SDC, and La0.6Sr0.4FeO3-SDC were successfully prepared by PLD method and it was found that insertion of PNCG-SDC or SSC-SDC double columnar film decreased the overpotential of SSC cathode. The power density of the cell deposited on Ni-Fe porous metal substrate was higher than 3W/cm2 at 773K and impedance results suggested that the increased power density was explained by decreased cathodic overpotential. Increased diffusivity of oxide ion in double columnar film is effective for expanding reaction area resulting in the increased cathodic performance for oxide ion dissociation.

Deep UV light sensitive Zn1−x−yMgxAlyO films with fast photoelectric response for SAW photodetectors

Optical, structural and photo-electric properties of Zn1−x−yMgxAlyO films on piezoelectric LiNbO3 substrates prepared by PLD method at varied temperatures are studied. The ZnO band gap is enlarged to ∼5 eV by Mg atoms dosing. The reduced growth temperature of 400 °C results in lower conductivity of the film. The films grown at 400 °C–500 °C show deep UV photoelectrical response of 0.1–0.2 ms which is 50–100 times faster compared to devices based on films produced at 600 °C with higher crystallinity. By moderate Al doping and varying the temperature of Zn(Mg, Al)O film growth one may tune the initial sheet conductivity, i.e. the ‘working point’ of UV SAW detector, to the abrupt slopes of Γ(σ) characteristics, thus, optimizing the sensor sensitivity and response time. The UV ‘light on/off’ sheet conductivity change Δσ/σdark, defining the sensitivity of UV SAW photodetector is tuned between ∼22% and ∼0.4%.

Magnetic Field Dependence of Magnetotransport Properties of MgB2/CrO2 Bilayer Thin Films

In this work, we comparatively investigated two MgB2 films: one (F1) was typically fabricated using the PLD method, while the other (F2) was fabricated using the same method but on top of a 100-nm-thick CrO2 layer. Both films had a thickness of 300 nm and were annealed ex situ at 700 °C for 30 min before being investigated under an external magnetic field of up to ± 7 T. The activation energy (Uo), upper critical field (HC2), irreversibility field (Hirr), magnetoresistance (MR), and I-V characteristics for the two films were studied in detail, and the results were compared with theoretical models. XRD analysis showed that both films are c-axis-oriented, while the RRR values for the films were found to be 1.6 and 1.89, respectively. Experimental data showed a broadening of the R-T transitions for an increasing magnetic field, with such broadening observed to be wider for F2 due to surface superconductivity. The activation energy under magnetic fields ranging from 0 to 7 T was calculated using our data and compared with a theoretical model. In both films, Uo followed a parabolic curve but was higher for F2 up to 6 T before sharply decreasing, while it continued to follow the same trend for F1 up to 7 T. The theoretical model was in good agreement with F1 for the full span of magnetic fields used. HC2 and Hirr were estimated and fitted using Ginzburg–Landau theory, but although the fitting was very good for F1, some modification in fitting parameters was required to obtain the same fitting for F2. Magnetoresistance and I-V characteristics confirm that the CrO2 layer in F2 leads to faster damage to the superconductivity property for high magnetic fields and temperatures.

A Flexible e-skin based on micro-structured PZT thin films prepared via a low-temperature PLD method

A flexible PZT-based e-skin that could withstand fatigue over extended periods of use (more than 10 000 cycles).

High signal/noise ratio deep UV detector with maximum response at 230 nm based on mix-phase MgZnO deposited under high laser energy condition

A Mix-phase MgZnO thin film was fabricated on the c-plane sapphire substrate (Mg0.4Zn0.6O target) under high laser energy density condition by the PLD method. The internal quantum efficiency of the detector based on the mix-phase MgZnO thin film at 230 nm deep UV light reached 86% at 40 V bias voltage. And the Iuv(230 nm)/Idark ratio of the MgZnO detector reached 864 at 40 V bias voltage, which is mainly caused by both the higher internal gain of the detector at deep UV light and its smaller Idark. The high internal gain of the detector is mainly due to the higher density of interfaces between the different structure of MgZnO grains in the mix-phase MgZnO thin film, which is caused by the higher laser energy density deposition condition certified by contrast experiments. The small Idark of the detector is mainly caused by the higher barriers in the mix-phase MgZnO thin film and more cubic MgZnO in the mix-phase MgZnO thin film, and higher laser energy density deposition condition and O-rich c-plane sapphire substrate surface are key factors, which also agree with the contrast experiments results. So when the mix-phase MgZnO thin film that is constituted by both a small number of narrower band gap hexagonal MgZnO and a large number of wide band gap cubic MgZnO is used in the deep UV detector, and the difference in band gaps between different structures of MgZnO is relatively higher, a higher signal/noise ratio of the device at 230 nm deep UV light is gained, which is meaningful for developing high-performance deep UV detection technology.

Magnetotransport properties of Ba(Fe1−xNix)2As2 thin films grown by PLD method

In this paper we report on the structural and superconducting properties of epitaxial Ba(Fe1−xNix)2As2 thin films with x = 0.035, 0.05, and 0.08 grown by pulsed laser deposition on CaF2. The superconducting transition temperatures are 20.9 K, 21.3 K, and 10.8 K for the nominal nickel concentrations x = 0.035, 0.05, and 0.08, respectively. A large contribution of the electron-electron interaction to the scattering processes is observed. The critical fields for Ba(Fe1−xNix)2As2 with x = 0.035 and 0.05 are higher than for single crystals and there is no noticeable contribution from the spin–orbit interaction to the pair breaking.

Improvement of uniformity of Ic distributions in long REBCO with BMO coated conductors by in-plume PLD method

Long REBa2Cu3OX (REBCO, RE: rare earth element) with BaMO3 (BMO, M: metal) coated conductors have been expected for the industrial and commercial applications at high temperatures in magnetic fields. Especially, the multi-filamentary structure long REBCO with BHO coated conductors are effective for control of the shielding current of coated conductor excited by applied magnetic fields and alternating-current loss. We fabricated long EuBa2Cu3OX (EuBCO) with BaHfO3 (BHO) coated conductors by the IBAD/PLD (conventional PLD) method, which showed the high in-field Ic values. However, in order to realize REBCO with BMO coated conductors for industrial and commercial applications, the much higher uniformity of not only longitudinal and but transversal Ic distributions of long coated conductors with high in-field performance is required. We have tried to develop the long EuBCO with BHO coated conductors by the in-plume (plane-plume) PLD method with high deposition rate of about 24 nm/s to obtain high in-filed performance and low production cost. More recently, we fabricated the 105 m long EuBCO with BHO coated conductors with high uniformity of longitudinal Ic distributions of 2.54 % (STDEV) by the in-plume (plane-plume) PLD method comparing with coated conductors by the conventional PLD method. We measured each Ic value of 8 filaments of 581 µm in width and slot of 20 µm in width for 0.6 m long EuBCO with BHO coated conductors by in-plume (plane-plume) PLD method. Ic distribution in a width direction of the EuBCO with BHO coated conductors by in-plume (plane-plume) PLD method is more uniform than that of the conventional PLD method.

Angular dependence of Jc in YBCO films with c-axis correlated nano-rods and in-plane-distributed nano-particles

The quasi-multilayered films consisting of YBa2Cu3Oy layers with BaSnO3 nano-rods and the pseudo layers of in-plane-distributed BaSnO3 nano-particles were fabricated using a PLD method, in order to clarify the pinning landscape simultaneously improving the critical current densities, Jcs, both at B || c and at B || ab. The insertion of the pseudo layers into YBa2Cu3Oy films contributes to the enhancement of Jc at B || ab but it is a tendency to reduce the Jc at B || c. When the density of the nano-particles per layer is decreased, by contrast, the Jc at B || ab can be enlarged without the reduction of the c-axis peak. This is attributed to the fragmentation of the channel for flux creep motion through the pseudo layers. Furthermore, the Jc in tilted magnetic fields off the c-axis enhances as well as c-axis peak in a high magnetic field, when BaSnO3 nano-particles are increased.

BMO-Doped REBCO-Coated Conductors for Uniform In-Field $I_{c}$ by Hot-Wall PLD Process Using IBAD Template

BaMO 3 (BMO, M: Zr or Hf)-doped REBCO-coated conductors were prepared by Hot-Wall PLD method on IBAD template. The highest J c was obtained for BaHfO 3 -doped EuBCO. Quite strong pinning force density (F p ) of 1.6 TN/m 3 was observed at 4.2 K, 15 T, for a sample deposited with growth rate of ~5 nm/s. It had strong c-axis correlated pinning at the temperature above 20 K with the matching field of ~5 T. A 45-m-long sample was formed by productive high growth rate over 20 nm/s, being consistent with commercial nondoped conductors. It had also large I c of 1687 A/cm and F p of 0.96 7 TN/m 3 was obtained at 4.2 K, 15 T. The end-to-end longitudinal Ic homogeneity (σ) at 77 K in low field was evaluated to be 2.2% by magnetization. Transport in-fields I c were also measured for the both end points at 30 K, 2 T, resulting in 1863 and 1883A/cm, respectively.

Highly conductive n-type NiCo2O4-δ epitaxial thin films grown by RF sputtering

NiCo2O4-δ (NCO) epitaxial thin films have been grown on MgAl2O4(001) substrates at different Ar/O2(1:1) pressure by RF sputtering technique. HRXRD study indicates best crystalline quality and smallest unit cell volume are obtained in NCO thin films deposited at 75Pa. Hall measurement reveals NCO thin films are of n-type conductivity with the electron mobility and electron density of NCO films in the range of 0.09–1.05cm2/Vs and 1.06–5.94×1021cm−3, respectively. Maximum conductivity of 178S/cm is obtained in NCO thin films deposited at 75Pa, which surpasses the conductivity of NCO films grown by using PLD method. XPS spectra confirm mixed valence states for nickel and cobalt ions, and existence of oxygen vacancies which triggers n-type conductivity. The deposition pressure dependent carrier density and unit cell volume are closely related to the concentration of oxygen vacancies.

Composition‐ratio control of CZTS films deposited by PLD

The control of the composition of the CZTS polycrystals has been examined. CZTS poly‐crystal, ZnS, and SnS powders were mixed for adjusting the composition and were sintered at temperature of 400 °C. We evaluated polycrystal with the molar ratios of Cu/(Zn+Sn) = 0.79, Zn/Sn = 1.04, and S/(Cu+Zn+Sn) = 0.95. Then, we prepared CZTS film by PLD method using the CZTS polycrystal as a target. Composition content of the film was also evaluated to be the molar ratios of Cu/(Zn+Sn) = 1.14, Zn/Sn = 1.04, and S/(Cu+Zn+Sn) = 0.69. The film indicats slightly Cu‐rich, and S‐poor compositions, and no change of Zn/Sn rate. Definitely, we successfully performed composition control and improvement of composition uniformity for polycrystals by using the source materials of CZTS, ZnS, and SnS. Additionally, we prepared homogeneous CZTS film with either a kesterite or a stannite structure by PLD method.

Thermally activated flux flow in superconducting epitaxial FeSe0.6Te0.4 thin film

The thermally activated flux flow effect has been studied in epitaxial FeSe0.6Te0.4 thin film grown by a PLD method through the electrical resistivity measurement under various magnetic fields for B//c and B//ab. The results showed that the thermally activated flux flow effect is well described by the nonlinear temperature-dependent activation energy. The evaluated apparent activation energy U0(B) is one order larger than the reported results and showed the double-linearity in both magnetic field directions. Furthermore, the FeSe0.6Te0.4 thin film shows the anisotropy of 5.6 near Tc and 2D-like superconducting behavior in thermally activated flux flow region. In addition, the vortex glass transition and the temperature dependence of the high critical fields were determined.

Influence of the substrate on the structure stability LaLuO3 thin films deposited by PLD method

LaLuO3 amorphous thin films were elaborated by pulsed laser deposition technique on different support: Si (100), Si(100) with buffer layer CeO2, MgO(111) and Al2O3 (1101). For obtained the crystallizes phase the thin films were annealed in temperature 1100 °C in air during 2 h. TEM analysis clearly showed the reaction between Si support and LaLuO3 thin films and their polycrystalline structure. The spectroscopy investigations indicate the reaction between Si support and LaLuO3 thin films and formation of silicates. The CeO2 thin buffer layers on Si support limited the reaction between support and thin films. No reactions were observed between the surface Al2O3 and MgO and thin films.

High performance solar-blind ultraviolet photo detector based on mixed-phase MgZnO thin film with different interfaces deposited by PLD method

MSM structure UV detectors were fabricated on mixed-phase MgZnO thin films with (200) cubic MgZnO/hexagonal MgZnO and (111) cubic MgZnO/hexagonal MgZnO interfaces by PLD method. Under 25 V bias voltage, the maximum responsivity of the mix-phase MgZnO based detector with (002) cubic MgZnO/hexagonal MgZnO interfaces reached 8 A/W at 256 nm because of 3809% internal gain of the detector at solar-blind UV light, which is two order of magnitude bigger than the detector with (111) cubic MgZnO/hexagonal MgZnO interfaces. The higher density of interface states between (200) cubic and hexagonal MgZnO grains in the mix-phase MgZnO thin film is main reason for its big internal gain and high solar-blind UV response. The Idark of the mixed-phase MgZnO based detector with (111) cubic MgZnO/hexagonal MgZnO interfaces is much smaller and the Ilight/Idark of which is higher because of the higher interfaces barrier at (111) cubic MgZnO/hexagonal MgZnO interfaces, so the detector could effectively detect faint solar-blind UV signal more under strong noise background.

Nanoscale thin film growth of Au on Si(111)-7 × 7 surface by pulsed laser deposition method

To obtain important information for fabricating atomic-scale Au thin films that are used for biosensors, we have observed the morphology of Au particles adsorbed on a Si(111)-7 × 7 surface, which is supposed to be the initial stage of Au atomistic thin film formation. Au particles were adsorbed on the clean Si surface using a PLD method, and the adsorbed particles were observed using a scanning tunneling microscope. As the number of laser shots was increased in the PLD method, the size of the adsorbed particle became larger. The larger particles seemed to form clusters, which are aggregations of particles in which each particle is distinguished, so we call this type of cluster a film-shaped cluster. In this work, we have mainly analyzed this type of cluster. As a result the film-shaped clusters were found to have a structure of nearly monoatomic layers. The particles in the clusters were gathered closely in roughly a 3-fold structure with an inter particle distance of 0.864 nm. We propose a model for the cluster structure by modifying Au(111) face so that each observed particle consists of three Au atoms.

Rapid thermal annealing induced modification in structural and electronic structure properties of Ti0.95Co0.05O2⿿δ thin films

Thin film of Ti0.95Co0.05O2-δ was deposited on Si (100) using PLD method and annealed in O2 and N2 environment. Raman spectra confirm that all the films have rutile structure. Surface morphology indicates that the surface roughness and grain size increase with annealing. The electronic structure studied by NEXAFS spectroscopy at O K, Ti L3,2 and Co L3,2-edges revealed that peak intensities decrease significantly for the film annealed N2 environment. The ligand-field splitting estimated from the energy difference between the t2g and eg features in O K-edge spectra were 2.71eV for as-deposited and O2 annealed film, whereas reduced more than double (⿼1.32eV) for the film annealed in N2. Atomic multiplet calculations and experimentally observed NEXAFS spectra at Co L3,2-edge and Ti L3,2-edge confirm that Co present in 2+ and Ti in +4 valence state, whereas the multiplet structures of O2 annealed film looks similar to Co metal.

Effect of Substrate Surface Atom Constitution and The Migration Characteristics of Reactive Atoms on Crystal Structure of MgxZn1–xO Thin Films Deposited by PLD Method

MgxZn1–xO thin films were deposited on fused quartz substrate by PLD method with Mg0.4Zn0.6O source target, and the effect of the substrate surface atom constitution and the migration characteristics of reactive atoms on crystal structure of the MgZnO thin films were studied. Under oxygen-deficient condition, MgxZn1–xO thin film deposited mainly along (200) orientation of cubic structure lattice at temperature below 350 °C because of the alternatively constituted substrate surface by Si and O atoms and the weak horizontal migration of reactive atoms, mix-constituted substrate surface(Si/O areas and O-rich areas) and the intense horizontal migration of reactive atoms introduced phase separation in MgxZn1–xO thin films deposited at higher temperature. Single cubic structure (200) Mg0.38Zn0.62O thin films was made at 300 °C with Zn composition over theoretical limit in bulk materials, the band gap of which reached 4.2 eV and the MgZnO thin film could detect 330 nm near-UV light. And the available UV range of...

Influence of atmosphere composition on the structure and properties of aluminum oxynitride coatings deposited by PLD method

Influence of atmosphere composition on the structure and properties of aluminum oxynitride coatings deposited by PLD method

PLD法で作製したSm-Co／α-Fe積層型ナノコンポジット磁石の磁気特性

PLD法で作製したSm-Co／α-Fe積層型ナノコンポジット磁石の磁気特性

Superior triethylamine-sensing properties based on TiO2/SnO2 n–n heterojunction nanosheets directly grown on ceramic tubes

A highly sensitive and selective gas sensor towards triethylamine (TEA) has been successfully fabricated by designing n–n heterojunctions consisting of SnO2 nanosheets and TiO2 nanoparticles. The SnO2 nanosheets with the thickness about 15nm were directly grown on Al2O3 ceramic tubes by a simple hydrothermal process. After the formation of n–n heterojunctions by employing PLD method, the TiO2 nanoparticle/SnO2 nanosheets heterojunctions exhibit high sensing properties to TEA gas. The as-prepared ST3 (SnO2/TiO2 3000) sensor response could reach to 52.3at relatively low temperature (260°C) when exposed to 100ppm TEA gas, which is much higher than that of pure SnO2 nanosheet sensor (∼3@100ppm TEA@320°C). Compared with the pure SnO2 nanosheet sensor (S sensor), the depletion layer formed at the n–n heterojunctions interface in TiO2/SnO2 sensor can greatly increase the resistance in air and decrease the resistance in TEA gas. Due to the general working principle and controllable growth strategy, this work provides a way for developing the chemiresistive gas sensors.