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Discusses the dislocation reduction in thin films via lateral overgrowth from trenches (LOFT). Structures of thin films before and after regrowth; Advantages of LOFT over epitaxial lateral overgrowth (ELO); Cross-sectional scanning electron microscope (SEM) images of thin films.

High-temperature superconductor GdBa2Cu3O7 thin films were grown in situ on LaAlO3 single-crystal substrates by dc magnetron sputtering using a single planar target. 93% samples had a zero resistance transition temperature Tc0 more than 90 K and a transition width less than 1 K. The best films had a Tc0 of 92.5 K, a transition width of 0.57 K, and a critical current density of 3.6×106 A/cm2 at 77 K. The reproducibility is very good. X-ray diffraction analysis showed c axis normal to the film’s surface. [ABSTRACT FROM AUTHOR]

Epitaxial BaTiO3 (BTO) films have been grown on Nb-doped SrTiO3 (NSTO) (0 0 1) substrate. The ferroelectric resistive switching effect and memristive behaviours have been observed in Pt/BTO/NSTO heterostructures. It exhibits two resistance states under different polarization, and both current–voltage curves are nonlinear, slightly asymmetric and free of discontinuities, in contrast with what often occurs with other resistive switching devices. In addition, the resistance can be continuously tuned up to 1.3 × 105% by varying pulse voltage amplitudes for the ferroelectric memristor application. Moreover, the device exhibits excellent retention and reproducibility. The above phenomena can be qualitatively explained by considering the modulation of the width and height of the potential barrier at the BTO/NSTO interface by ferroelectric polarization. [ABSTRACT FROM AUTHOR]

We investigate the third-order optical nonlinearity in ZnO/Al2O3 nanolaminates fabricated by atomic layer deposition and show that the third-order optical nonlinearity can be enhanced by nanoscale engineering of the thin film structure. The grain size of the polycrystalline ZnO film is controlled by varying the thickness of the ZnO layers in the nanolaminate in which thin (∼2 nm) amorphous Al2O3 layers work as stopping layers for ZnO crystal growth. Nanoscale engineering enables us to achieve a third harmonic generated signal enhancement of ∼13 times from the optimized nanolaminate structure compared to a ZnO reference film of comparable thickness. [ABSTRACT FROM AUTHOR]

We have used an ion beam sputtered Y2O3-Al2O3 (YALO) composite to simplify the architecture of high temperature superconducting (HTS) coated conductors (CCs) based on a IBAD MgO template. By implementing YALO, we have reduced the total non-superconducting layers between the polycrystalline metal substrate and the superconducting film from five (the standard architecture) to four. Well textured (Y,Gd)Ba2Cu3O7[?]x ((Y, Gd)BCO) films have been successfully grown by MOCVD on this simplified template. The microstructural characterization revealed that all layers are continuous and uniform with sharp and clean interfaces. Additionally, the YALO maintained its amorphous nature after the deposition of the superconductive layer, which is a plus in terms of its efficiency as a diffusion barrier. The achievement of a self-field critical current of 230 A cm[?]1 at 75.5 K is another proof of the effectiveness of YALO as a diffusion barrier and nucleation seed for the MgO. The transport properties under an applied magnetic field of MOCVD grown (Y, Gd)BCO on LMO buffered MgO/YALO/Ni-alloy are comparable with those of (Y, Gd)BCO on a standard architecture, thus demonstrating good compatibility between the simplified template with the MOCVD grown (Y, Gd)BCO. The use of a single composite YALO layer instead of individual layers of Y2O3 and Al2O3 for the large scale fabrication of HTS CCs based on IBAD MgO provides advantages such as potentially reduced cost due to the reduced number of fabrication steps. [ABSTRACT FROM AUTHOR]

Systematic effects of Zr additions on the structural and flux pinning properties of YBa2Cu3O7[?]d (YBCO) films deposited by metal-organic chemical vapor deposition (MOCVD) have been investigated. Detailed characterization, conducted by coordinated transport, x-ray diffraction, scanning and transmission electron microscopy analyses, and imaging Raman microscopy have revealed trends in the resulting property/performance correlations of these films with respect to varying mole percentages (mol%) of added Zr. For compositions [?]7.5 mol%, Zr additions lead to improved in-field critical current density, as well as extra correlated pinning along the c-axis direction of the YBCO films via the formation of columnar, self-assembled stacks of BaZrO3 nanodots. [ABSTRACT FROM AUTHOR]

Epitaxial ZnO thin films doped uniformly with nitrogen at 1020 atoms/cm3 were fabricated by pulsed laser ablation of a Zn-rich Zn3N2 target. The films grown at 300 °C and annealed at 600 °C in O2 showed p-type conductivity. Two acceptor levels at 105 and 224 meV were determined by temperature-dependent Hall and photoluminescence measurements of the p-type samples. Transmission electron microscopy studies revealed that the p-type ZnO films consist of 10-20 nm columnar grains with a high density of defects and grain boundaries that may facilitate the annihilation of native donors and the activation of acceptors during postdeposition annealing. [ABSTRACT FROM AUTHOR]

Thermal diffusivity (α) of amorphous silicon carbon nitride (a-SiC[sub x]N[sub y]) thin films on crystalline silicon, prepared by ion beam sputtering, has been studied using the traveling wave technique. The variation of thermal diffusivity with carbon content in amorphous silicon carbon nitride samples are reported. Thermal diffusivity decreased from ∼0.35 cm[sup 2]/s for samples with carbon contents of less than 30 at. %, to about 0.15 cm[sup 2]/s for a-SiC[sub x]N[sub y] films with a carbon content of ∼70 at. %. A similar variation was found for the film density as measured by surface acoustic wave spectroscopy as a function of the carbon content. The results on a-SiC[sub x]N[sub y], elucidate the relation between thermal diffusivity and the bonding configuration, density and microstructure of the network. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

X-ray absorption near-edge structure (XANES) measurements have been performed for nitrogen (N) containing diamond films with three different N concentrations at the C K-edge using the sample drain current mode. The C K-edge XANES spectra of these diamond films resemble that of the pure diamond regardless of the N concentration, which suggests that the overall bonding configuration of the C atom is unaltered. N impurities are found to reduce the intensities of both the sp[sup 2]- and sp[sup 3]-bond derived resonance features in the XANES spectra. The valence-band photoelectron spectra indicate that N atoms cause the broadening of the valence band σ- and π-bond features and the enhancement and reduction of the σ- and π-bond features, respectively. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Presents a correction to the article 'Biexciton emission from high-quality ZnO films grown on epitaxial GaN by plasma-assisted molecular-beam epitaxy,' published in the year 2000 issue of the 'Applied Physics Letters' journal.

We have investigated the structural and optical properties of Ga-doped ZnO films grown on GaN templates by plasma-assisted molecular-beam epitaxy. The carrier concentration in Ga-doped ZnO films can be controlled from 1.33x10[sup 18]/cm[sup 3] to 1.13x10[sup 20]/cm[sup 3]. Despite high Ga incorporation, the linewidth of (0002) ω-rocking curves of Ga-doped ZnO films still lies in the range from 5 to 15 arc min. Photoluminescence (PL) spectra of Ga-doped ZnO films show dominant near-bandedge emission with negligibly weak deep-level emission, independent of carrier concentration. The PL spectrum exhibits a new emission line at 3.358 eV, which corresponds to exciton emission bound to a Ga donor. To avoid degradation of the PL intensity, the maximum dopability of Ga in ZnO is determined to be around 2.6x10[sup 19]/cm[sup 3]. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Mo¨ssbauer and magnetic studies have shown that 1-2 wt % of SiO[sub 2] could be dissolved in the CoFe[sub 2]O[sub 4] structure. Changes in magnetization and Curie temperature were observed. The presence of SiO[sub 2] might enhance magnetic anisotropy. Coercivity values of up to 3.5 kOe were measured for mechanically alloyed CoFe[sub 2]O[sub 4]/SiO[sub 2] powders. High coercivities were also achieved in SiO[sub 2]-doped Co-ferrite thin films prepared by sputtering technique. The Co-ferrite thin film deposited on a silicon wafer using a 5 wt % SiO[sub 2]/Co-ferrite target possessed a coercivity of 7.4 kOe. Spring-magnet behavior was observed, indicating the possible presence of remanence enhancement due to exchange coupling because of nanocrystalline structure. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Nanometer SiO[sub 2]/nanometer Si/nanometer SiO[sub 2] double-barrier (DB) structures, with Si layers having eleven different thicknesses from 2 to 4 nm, were deposited on n[sup +]-Si substrates using the magnetron sputtering technique. Strong electroluminescence (EL) from semitransparent Au film/DB/n[sup +]-Si structure was observed under reverse bias in a range of about 5-7 V. It is found that every EL spectrum of the structure can be decomposed into two Gaussian bands with peaks at around 1.85 and 2.25 eV, and their intensities and current swing synchronously with increasing nanometer Si layer thickness; the periodic length of swing is consistent with half of the de Broglie wavelength of the carriers. A comparison was carried out between EL from the Au/DB/n[sup +]-Si structure under reverse bias and that from the Au/DB/p-Si structure under forward bias reported previously. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A magnetic force microscope (MFM) was used to image the topography and magnetic microstructures of Co[sub 22]Ag[sub 78] granular films. The observed morphology shows isolated nanometer-scale cobalt particles (granules) embedded in the silver matrix. Stripe magnetic domains with much larger size (typically of ∼100 nm wide) than that of cobalt particles are resolved clearly on MFM micrographs for the annealed samples. It is demonstrated that the domain width and the relative magnetic force strength first increases and then decreases with annealing temperature with a maximum at about 600 K. We suggest that the appearance of the stripe domains is attributed to magnetic correlation among many of the isolated single-domain cobalt particles and is dependent on the microstructure of the samples. © 1998 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Crystalline thin films of SiCN have been grown by microwave plasma-enhanced chemical vapor deposition using H[sub 2], CH[sub 4], N[sub 2], and SiH[sub 4] gases. The ternary compound (C;Si)[sub x]N[sub y] exhibits a hexagonal structure and consists of a network wherein the Si and C are substitutional elements. While the N content of the compound is about 35–40 at. %, the extent of Si substitution varies and can be as low as 10 at. %. Optical properties of the SiCN compounds have been studied by photoluminescence (PL), piezoreflectance (PzR), and photothermal deflection (PDS) spectroscopies. From the PzR measurement, we determine the direct band gap of the new crystals to be around 3.8 eV at room temperature. PDS measurement shows two absorption features with the first peak at around 3.2 eV which is related to an indirect band gap. The second PDS peak occurred around 3.8 eV and is quite consistent with the direct band gap determined by PzR. From the PL measurement, it is also found that the SiCN compounds have a near band edge emission centered around 3.26 eV at room temperature, which is consistent with the fundamental band gap obtained from the PDS measurement. These optical results indicate the potential of SiCN for blue and uv optoelectronic applications. © 1998 American Institute of Physics. [ABSTRACT FROM AUTHOR]

In this study, we used low-cost non-vacuum electrochemical coating methodsto prepare Cu (In1-xGax) Se2 precursor films on Mo/SLG substrates for the CIGS absorber applications. To find the most suitable growth conditions, we applied two types of electrodeposition conditions: the constantpotentialelectrodeposition and pulsed electrodeposition. To examine the material properties of the film, the surface morphology, composition, and crystal structure analyses of the CIGS films were investigated by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD), respectively. The results show that pulse electrodeposition process with an appropriate duty cycle, pulse period and depositionvoltage could significantly improve the CIGS film quality. The pulse deposited CIGS films show promises for future CIGS solar cell applications. [ABSTRACT FROM AUTHOR]

Abstract: A two-layer porous NiO film is prepared by hydrothermal synthesis method through self-assembled monolayer polystyrene spheres template. The substructure of the NiO film is composed of ordered close-packed hollow-sphere array and the superstructure is made up of randomly NiO nanoflakes. The electrochemical properties are measured by galvanostatic charge/discharge tests and cyclic voltammetric analysis (CV). As anode material for lithium ion batteries, the two-layer porous NiO film exhibits high initial coulombic efficiency of 75%, high reversible capacity and rather good cycling performance. The discharge capacity of the two-layer porous NiO film is 501mAhg−1 at 0.5C after 50 cycles. The two-layer porous architecture is responsible for the enhancement of electrochemical properties. [Copyright &y& Elsevier]

Hexagonal barium ferrite films were deposited on Si (111) substrates by radio-frequency magnetron sputter deposition. The films exhibited strong c-axis perpendicular orientation benefiting from a Pt buffer layer. The results include measurements of crystallographic structure, magnetic domain structure, and magnetic and microwave properties for barium hexaferrite films with different thicknesses of Pt underlayers, revealing ferromagnetic resonance linewidths, ΔH =400–600 Oe at 40–60GHz. These results provide a viable pathway to realizing miniaturized microwave devices integrated with semiconductor device platforms. [Copyright &y& Elsevier]

Abstract: Ag-doped ZnO thin films were prepared on glass substrates by radio frequency co-reactive magnetron sputtering technique. The effects of Ag-doping on the microstructure and optical properties of the ZnO thin films were studied by X-ray diffraction (XRD) and UV–visible spectroscopy. The photoluminescence (PL) measurements at room temperature revealed an ultraviolet and a blue emission. The origin of these emissions was discussed. It was also demonstrated that the optical band edge shifted to a shorter wavelength first as Ag is incorporated, and then to a longer wavelength with the increasing of Ag-doping concentration. The optical band gaps calculated based on the quantum confinement model are in good agreement with the experimental values. [Copyright &y& Elsevier]

Abstract: V1−x−y W x Si y O2 films for uncooled thermal detectors were coated on sodium-free glass slides with sol–gel process, followed by the calcination under a reducing atmosphere (Ar/H2 5%). The V1−x−y W x Si y O2 films as prepared inherit various phase transition temperatures ranging from 20 to 70°C depending on the dopant concentrations and the fabrication conditions. Compared to the hysteresis loop of plain VO2 films, a rather steep loop was obtained with the addition of tungsten components, while a relaxed hysteresis loop with the tight bandwidth was contributed by Si dopants. Furthermore, the films with switching temperature close to room temperature were fabricated to one-element bolometers to characterize their figures of merit. Results showed that the V0.905W0.02Si0.075O2 film presented a satisfactory responsivity of 2600V/W and detectivity of 9×106 cm Hz1/2/W with chopper frequencies ranging from 30 to 60Hz at room temperature. It was proposed that with appropriate amount of silicon and tungsten dopants mixed in the VO2, the film would characterize both a relaxed hysteresis loop and a fair TCR value, which effectively reduced the magnitude of noise equivalent power without compromising its performance in detectivity and responsivity. [Copyright &y& Elsevier]

Er-doped Si-rich SiO2 (SRSO:Er) films with excess silicon contents of 0, 10, 20 and 30% were deposited on p-Si substrates using the magnetron sputtering technique, and then Au/SRSO:Er/p-Si light-emitting diodes (LEDs) were fabricated after the SRSO:Er/p-Si samples were annealed separately at 600, 700, 800, 900 and 1000 °C. Room temperature 1.54-μm electroluminescence (EL) from the Au/SRSO:Er/p-Si LEDs was observed when the forward bias was above 4 V. It was found that excess silicon with a proper content in a SRSO:Er film annealed at a suitable temperature can evidently enhance EL intensity of the LED made of the film. The optimum annealing temperatures for enhancing EL intensity were 900, 900, 800 and 700 °C for the SRSO:Er films containing 0, 10, 20 and 30% excess silicon, respectively. The 1.54-μm EL intensity of the Au/SRSO:Er/p-Si LED made of a SRSO:Er film with 20% excess silicon being annealed at 800 °C was the most intense. [Copyright &y& Elsevier]

We report the enhancement of fracture toughness and strength of a cobalt‑tantalum-based metallic glass thin film with increasing boron content. The improvement of the mechanical performance is attributed to the formation of a compositionally lamellar compared to uniform glass microstructure, which becomes thinner with increasing boron content as revealed by transmission electron microscopy. Compositional variations across the lamellar structure are revealed by atom probe tomography. Cobalt- and boron-rich regions alternate sequentially, whereas tantalum exhibits slight variations across the lamellae. Our results can be utilized in future design efforts for metallic glass thin films with outstanding mechanical performance. [ABSTRACT FROM AUTHOR]

Face-centered cubic (FCC) metals are in general vulnerable to high-energy ion irradiation. Twin boundaries have been shown to improve the irradiation tolerance of FCC metals. However, nanotwins in monolithic metals are unstable during irradiation. In this study, we show that Fe solute can drastically improve irradiation stability of twin boundaries in Ag. By adding merely 1 at.% of Fe solute atoms into Ag matrix, ultra-high-density twins with an average twin thickness of ∼3 nm form in Ag. In situ Kr ion irradiation studies show that defect size and density in Ag 99 Fe 1 have been significantly reduced comparing with monolithic coarse-grained Ag and nanotwinned Ag. Furthermore, these extremely fine twins survived heavy ion irradiations. Density function theory calculations suggest that Fe solutes stabilize nanotwins by pinning twin boundaries. The mechanisms of enhanced radiation tolerance enabled by solute-twin boundary networks are discussed. [ABSTRACT FROM AUTHOR]

In this paper, we propose a simple but effective method to prepare high-quality (100)-oriented (Na 0.85 K 0.15 ) 0.5 Bi 0.5 TiO 3 (NKBT) thin films with outstanding electric properties by a sol-gel spin-on technique. By introducing a LaNiO 3 seed layer between the substrate and thin film, we simultaneously achieved crystallization at temperatures as low as 450 °C and controlled orientation. X-ray diffraction and X-ray reflectometry indicated that the NKBT/LNO thin film annealed at 500 °C was highly (100)-oriented, and had clear interfaces without diffusion, effectively reducing the dielectric constant and leakage current. Additionally, due to its high (100) orientation and clear interface, the NKBT thin film annealed at 500 °C had high displacement and a high pyroelectric coefficient, giving it a higher pyroelectric figure of merit than those of previously reported films. This study provides a new and simple method for preparing highly oriented lead-free thin films at low temperatures, and it extends the possible applications of these films to integration with silicon substrates. [ABSTRACT FROM AUTHOR]

Highlights: [•] A new method was developed to prepare dualistic soft magnetic nanocomposite thin films. [•] The structure and magnetic properties of nanocomposite thin films were investigated. [•] The soft magnetic properties of Ni0.5Zn0.5Fe2O4 thin films have been greatly improved. [Copyright &y& Elsevier]

CIGS film was formed using one-step electrochemical deposition at various deposition potential voltages in solution with diverse pH values. Multiple material analyses such as X-ray diffraction (XRD) analysis, scanning electron microscope (SEM) images, energy dispersive spectroscopy (EDS), and electron probe micro-analyzer (EPMA) images were used to examine the electro-deposition parameters. UV spectrometer was performed to measure the bandgap of the CIGS thin film. A highest Ga composition could be obtained at the most negative voltage of -3.3V and the smallest pH value of 1.6 in our experiment. However, an inferior material property and worse crystalline phase might come with a high Ga concentration. The band gap of the electro-deposited CIGS film with Cu:In:Ga:Se ratio of 1:0.52:0.30:1.98 could achieve 1.16 eV. The electrodeposited CIGS film shows promises for future solar cell applications. [ABSTRACT FROM AUTHOR]

Platinum (Pt) metal, being nonmagnetic and with a strong spin-orbit coupling interaction, has been central in detecting the pure spin current and establishing most of the recent spin-based phenomena. Magnetotransport measurements, both electrical and thermal, conclusively show strong ferromagnetic characteristics in thin Pt films on the ferromagnetic insulator due to the magnetic proximity effects. The pure spin current phenomena measured by Pt, including the inverse spin Hall and the spin Seebeck effects, are thus contaminated and not exclusively established. [ABSTRACT FROM AUTHOR]

The initial growth modes of Bi4LaTi3FeO15 thin films on (001) SrTiO3, (001) MgO and (001) Y:ZrO2 (YSZ) substrates are studied. Detailed crystal structure, microstructure and surface morphology characterizations substantiate that Bi4LaTi3FeO15 films grow on these substrates via three-dimensional grain growth mode. The synthesized Bi4LaTi3FeO15 films on (001) MgO and (001) SrTiO3 substrates do have c-axis epitaxial Aurivillius layered structure, and have relative smooth surface roughness. While films grown on (001) YSZ show the polycrystalline quality with large surface roughness. The different crystal quality of films grown on MgO/SrTiO3 and YSZ substrates is explained qualitatively by considering the different atomic surface structures of these substrates. [ABSTRACT FROM AUTHOR]

Abstract: In this letter, we propose a method to fabricate Fe80Ni20–O film with improved static and high-frequency, magnetic and electrical properties. Fe80Ni20–O alloy films were prepared by direct current magnetron sputtering at room temperature. The results show that the in-plane uniaxial magnetic anisotropy fields can be adjusted in a broad range by solely adding a very low dose of oxygen into Fe80Ni20 alloy films without applying any inducing field on substrates during deposition. By increasing the oxygen flow ratio from 0.75% to 3%, Fe80Ni20–O alloy films could be achieved with an adjustable ferromagnetic resonance frequency f r (from 2.2 to 5.9GHz), a large saturation magnetization 4πMs (from 16.7 to 15.2kG), and a high resistivity ρ (from 56.7 to 108μΩcm). [Copyright &y& Elsevier]

The anisotropic irreversibility field BIrr of two YBa2Cu3O7-x thin films doped with additional rare earth (RE) = (Gd, Y) and Zr and containing strong correlated pins (splayed BaZrO3 nanorods and RE2O3 nanoprecipitates) has been measured over a very broad range up to 45 T at temperatures 56 K < T < Tc. We found that the experimental angular dependence of BIrr (θ) does not follow the mass anisotropy scaling BIrr (θ) = BIrr (0)(cos² θ + γ-2 sin² θ)-1/2, where γ = (mc/mab)1/2 = 5-6 for the RE-doped YBa2Cu3O7-x (REBCO) crystals, mab and mc are the effective masses along the ab plane and the c-axis, respectively, and θ is the angle between B and the c-axis. For B parallel to the ab planes and to the c-axis correlated pinning strongly enhances BIrr, while at intermediate angles, BIrr (θ) follows the scaling behavior BIrr (θ) ∝ (cos² θ + γRP-2sin² θ)-1/2 with the effective anisotropy factor γRP ≈ 3 significantly smaller than the mass anisotropy would suggest. In spite of the strong effects of c-axis BaZrO3 nanorods, we found even greater enhancements of BIrr for fields along the ab planes than for fields parallel to the c-axis, as well as different temperature dependences of the correlated pinning contributions to BIrr for B//ab and B//c. Our results show that the dense and strong pins, which can now be incorporated into REBCO thin films in a controlled way, exert major and diverse effects on the measured vortex pinning anisotropy and the irreversibility field over wide ranges of B and T. In particular, we show that the relative contribution of correlated pinning to BIrr for B//c increases as the temperature increases due to the suppression of thermal fluctuations of vortices by splayed distribution of BaZrO3 nanorods. [ABSTRACT FROM AUTHOR]

Microelectromechanical systems (MEMS) incorporating active piezoelectric layers offer integrated actuation, sensing, and transduction. The broad implementation of such active MEMS has tong been constrained by the inability to integrate materials with giant piezoelectric response, such a Pb(Mg1/32/3O3-PbTiO3 (PMN-PT). We synthesized high-quality PMN-PT epitaxial thin films on vicinal (003.) Si wafers with the use of an epitaxia[ (003.) SrTiO3 template layer with superior piezoelectric coefficients (e31,f= -27 ± 3 coulombs per square meter) and figures of merit for piezoelectric energy-harvesting systems. We have incorporated these heterostructures into microcantitevers that are actuated with extremely low drive voltage due to thin-film piezoelectric properties that rival bulk PMN-PT single crystals. These epitaxial heterostructures exhibit very large electromechanical coupling for ultrasound medical imaging, microfluidic control, mechanical sensing, and energy harvesting. [ABSTRACT FROM AUTHOR]

Abstract: Arrays of ferroelectric PZT nanowires with lateral size down to 200nm were fabricated by nanoembossing technology. Structural characterization of the embossed PZT film was studied by Raman spectroscopy. Multidomain configurations of a single nanowire have been explored by vertical mode piezoresponse force microscopy (VPFM). The local electric polarization of the individual ferroelectric nanowire has also been investigated. Excellent ferroelectric and piezoelectric characteristics observed in the embossed PZT nanowires suggest nanoembossing technique proposed in this work is promising to become a useful method for ferroelectric nanowires fabrication. [Copyright &y& Elsevier]

High transparency and conductivity of transparent conducting oxide thin film are very important for improving the efficiency of solar cells. ZnO thin film is a better candidate for transparent conductive layer of solar cell. N-type ZnO thin films were prepared by radio-frequency magnetron sputtering on glass substrates. ZnO thin films underwent annealing treatment after deposition. The influence of the sputtering power on the surface morphology, the electrical and optical properties were studied by AFM, XRD, UV2450 and HMS-3000. The experimental results indicate that the crystal quality of ZnO thin film is improved and all films show higher c-axis orientation with increasing sputtering power from 50 to 125 W. The average transparency of ZnO thin films is higher than 90% in the range of 400-900 nm between the sputtering power of 50-100 W. After the rapid thermal annealing at 550°C for 300 s under N2 ambient, the minimum resistivity reach to 10-2Ω⋅cm. [ABSTRACT FROM AUTHOR]

The preferred growth orientations of YBa2Cu3O7–δ (YBCO) thin films on (100) MgO substrates produced by pulsed laser deposition are reported. In particular, (103) perpendicular oriented films were successfully demonstrated. The crystallographic properties of the oriented films were examined by transmission electron microscopy and X-ray diffraction pole figure analyses, indicating a 45° tilt of the superconducting CuO2 planes relative to the substrate surface. This work provides a unique pathway to realizing the growth of (103) oriented YBCO films on highly valued electronic and microwave (100) MgO substrates. [ABSTRACT FROM AUTHOR]

The effects of annealing temperatures 600, 650, 700, and 750 °C on microstructure, chemical composition, leakage current, ferroelectric, dielectric, and piezoelectric properties of Bi3.15Eu0.85Ti3O12 (BET) thin films prepared by metal–organic decomposition were studied in detail. The largest spontaneous polarization 2 Ps (98.7 μC/cm2 under 300 kV/cm), remnant polarization 2 Pr (81.7 μC/cm2 under 300 kV/cm), dielectric constant εr (889.4 at 100 kHz), effective piezoelectric coefficient d33 (46.7 pm/V under 260 kV/cm), and lowest leakage current (1.3 × 10−6 A/cm2 under 125 kV/cm) of BET thin film were obtained with annealing at 700 °C. The mechanisms concerning the dependence of the enhancement d33 are discussed according to the phenomenological equation, and the improved piezoelectric performance could make BET thin film a promising candidate for piezoelectric thin film devices. [ABSTRACT FROM AUTHOR]

Abstract: Soft ultraviolet nanoimprint lithography is a cost-effective and versatile technique for the transfer of nano-scaled patterns to various surfaces. Here, we report on the fabrication of sub-micron square pillar arrays in epitaxial Ba0.7Sr0.3TiO3 ceramic films, using a combination of nanoimprint lithography and inductively coupled plasma etching techniques. Based on a similar approach we have also succeeded in preparing positive (direct) and negative (inverse) replicas of silicon master molds. Such a generic process could find application in various materials. [Copyright &y& Elsevier]

Single-phase CuInSe2 films were grown by high vapor selenization of CuIn alloy precursors within a partially closed graphite box. The CuIn precursors were prepared using CuxIny alloy targets with different composition rates under low vacuum level by a homemade sputtering system. The Cu and In composition rates of the used targets are 11:9, 10:10, and 9:11, respectively. The metallic precursor films were selenized using a two-step temperature profile, i.e. at 250°C and 400–500°C, respectively. The influence of the temperature at the second selenization step on the quality of the CIS absorbing layers was investigated. The CIS films were characterized by X-ray diffractometry, scanning electron microscopy, energy dispersive X-ray analysis, and Raman spectroscopy. The deposited CIS absorbers selenized at a high temperature of 500°C for 30 min exhibited a single-phase chalcopyrite structure with a preferential orientation in the (112) direction. These layers display uniform, large, and densely packed crystals with a grain size of about 3–5 μm. Cadmium sulfide buffer layer was manufactured by chemical bath deposition method. Bilayers ZnO/ZnO:Al were prepared by RF magnetron sputtering deposition. CIS solar cells with an efficiency of about 6.5% were produced without antireflective films. The method to fabricate CIS solar cells by a combination of the low vacuum sputtering deposition and the graphite box selenization process has provided a simple control process and shown a promising potential for developing high efficient and low-cost CuInSe2 solar cells. [ABSTRACT FROM AUTHOR]

Abstract: A new X-ray diffraction technique is developed to probe structural variations at the interfaces between epitaxy thin films and single-crystal substrates. The technique utilizes three-wave Bragg-surface diffraction, where a symmetric Bragg reflection and an asymmetric surface reflection are involved. The propagation of the latter along the interfaces conveys structural information about the interfacial region between the substrate and epi-layers. The sample systems of Au/GaAs(001) are subject to the three-wave diffraction investigation using synchrotron radiation. The GaAs three-wave Bragg-surface diffractions, (006)/(11¯3) and (006)/(1¯1¯3), are employed. The images of the surface diffracted waves are recorded with an image plate. The obtained images show relative positions of diffraction spots near the image of the interfacial boundary, which give the variation of lattice constant along the surface normal and in-plane directions. With the aid of grazing-incidence diffraction, three-dimensional mapping of strain field at the interfaces is possible. Details about this diffraction technique and the analysis procedures are discussed. [Copyright &y& Elsevier]

Abstract: Soft UV nanoimprint lithography and reactive ion etch techniques have been used to pattern high density and high aspect ratio nanostructures on the surface of a plastic plate such as Plexiglas. A thin film of photo-curable resist is first spin coated on the plastic plate, with or without deposition of a 10nm thick germanium intermediate layer. Then, a soft stamp made of poly-dimethylsiloxane (PDMS) is used to mold the photo-curable resist, followed by a UV light exposure. Finally, the imprinted pattern is used as mask for a sequential reactive ion etch of the residual resist layer, the intermediate layer if any, and the plastic plate. Such a soft nanoimprint and direct etch technique allowed us to obtain high density nanostructures with an aspect ratio up to 15. To demonstrate the applicability of such systems in biology, wetting behaviours and surface functionalization with fluorescent protein molecules have been studied. We believe that this low cost approach is high throughput and efficient for a number of applications. [Copyright &y& Elsevier]

Biaxial compressive strain has been used to markedly enhance the ferroelectric properties of BaTiO[sub 3] thin films. This strain, imposed by coherent epitaxy, can result in a ferroelectric transition temperature nearly 500°C higher and a remanent polarization at least 250% higher than bulk BaTiO[sub 3] single crystals. This work demonstrates a route to a lead-free ferroelectric for nonvolatile memories and electro-optic devices. [ABSTRACT FROM AUTHOR]

Abstract: The tetragonal (Pb0.8Ca0.2)TiO3 (PCT) thin films with and without Pb0.8La0.1Ca0.1Ti0.975O3 (PLCT) seed layer were deposited on the Pt(111)/Ti/SiO2/Si substrates by rf magnetron sputtering. The influence of seed layer on microstructures and electric properties of the PCT films was investigated, it was found that the PCT film without seed layer showed random orientation, while the film with seed layer exhibited strong (100) orientation. The PCT thin film with 14nm-thick PLCT seed layer displayed enhanced electrical properties such as a large pyroelectric coefficient (256μC/m2 K) and a low leakage current density (J <2×10−5 A/cm2) at room temperature. The resulting high figure-of-merit (F d =173μC/m2 K) indicates the highly oriented film good candidate for pyroelectric thin-film devices. [Copyright &y& Elsevier]

Abstract: Online impedance monitoring of cell suspensions can be performed with integrated microelectrode array in microfluidic devices. However, its accuracy is affected by the formation of cell aggregates on the surface of the electrode array. To make this technical more reliable, we deposited a thin film of agarose which is highly permeable to soluble ions on the electrodes. The growth behavior of yeast cells in YPD medium was studied for more than 24h and the recorded impedance spectra were used to determinate the cell metabolism induced changes of the medium resistance and the double layer capacitance as a function of time. Our results showed a much more important variation of the double layer capacitance, indicating the importance of online monitoring at low frequencies. [Copyright &y& Elsevier]

Abstract: This paper presents a comparative study of three methods for preparing integrated nanoporous TiO2 films for microfluidic based photocatalytic reactors. These porous films have inherent merit of large surface-to-volume ratio and should significantly improve the device photoreactivity. It is also expected that nanoporous thin films have different performance in microfluidic chambers from that in an open environment. Experimentally, films produced by water-based P25 TiO2 colloids and alcohol-based P25 TiO2 colloids as well as tetrabutyl titanate sol–gel have been implemented into both microfluidic chambers and bulk containers for a close comparison using photocatalytic induced degradation of methylene blue model chemical. The results show that although the water-based P25 method produces TiO2 films with lower performance than the alcohol-based P25 method in the bulk container, it achieves the highest reaction rate in the microreactor (1.4%s−1, 17% higher than the alcohol-based P25 method and seven times higher than the TBT synthesis method). Such comparison suggests that the water-based P25 method may be a good choice for the microreactor. [Copyright &y& Elsevier]

BiFeO3 thin films have been deposited on (111) SrTiO3 single crystal substrates by reactive molecular-beam epitaxy in an adsorption-controlled growth regime. This is achieved by supplying a bismuth overpressure and utilizing the differential vapor pressures between bismuth oxides and BiFeO3 to control stoichiometry. Four-circle x-ray diffraction reveals phase-pure, untwinned, epitaxial, (0001)-oriented films with rocking curve full width at half maximum values as narrow as 25 arc sec (0.007°). Second harmonic generation polar plots combined with diffraction establish the crystallographic point group of these untwinned epitaxial films to be 3m at room temperature. [ABSTRACT FROM AUTHOR]