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This study reports the synthesis of a few-layered graphene (GF) thin film on Ni foam by chemical vapor deposition (CVD) technique and investigation of its electrochemical performance as a negative electrode for lithium-ion batteries (LIBs). A standard deposition procedure with a methane precursor was employed to prepare the GF films. The SEM studies revealed the formation of a dark uniform film on the surface of Ni foam's wires upon the CVD deposition. The film consisted of numerous GF sheets replicating the shape of the Ni grain boundaries over the Ni wire surface. The Raman spectroscopy of the prepared films on the Ni foam confirmed that the samples are a few-layered GF with high quality and purity. In order to evaluate the potential of the use of the prepared materials as an anode in LIBs, their electrochemical performance was studied in coin-type lithium halfcells using cyclic voltammetry (CV) and galvanostatic cycling. The results of CV showed that both graphene and native oxide layer (NiO) on nickel foam exhibit electrochemical activity with respect to lithium ions. Galvanostatic cycling revealed that both GF and NiO contribute to the overall capacity, which increases upon cycling with a stable Coulombic efficiency of around 99%. The designed 3D GF coated NiO/Ni anode demonstrated a gradual increase of its areal charge capacity from 65 μAh cm-2 at the initial cycle to 250 μAh cm-2 at the final 250th cycle. [ABSTRACT FROM AUTHOR]

Studies the effect of sputtering condition on the dynamic characteristics and microstructures of magneto-optical silicon nitride (SiN)/TbFeCo/SiN/aluminum disks for recording media. Reasons for the attention given to transition-metal-rich terbium-iron-cobalt (Tb-Fe-Co) amorphous thin film alloys; Influence of the sputtering parameters of the magneto-optical layer on the static magnetic properties of Tb-Fe-Co; Analysis of the chemical composition of the magneto-optical films.

Lead-free polycrystalline (K0.48Na0.52)1+x(Nb0.55Ta0.45)O3(x = 0, 0.01, 0.02 and 0.03) thin films have been grown on Pt(111)/Ti/SiO2/Si substrates using KrF excimer laser ablation to investigate the effects of A-site ion excess. The film at x = 0.01 exhibited good ferroelectric hysteresis loop with a remnant polarization 2Prof 30 μC/cm2and coercive field 2Ecof 61 kV/cm. The piezoelectric coefficientd33,fof the KNNT film with x = 0.01 was found to amount to 79 pm/V. These improved ferroelectric and piezoelectric properties were attributed to the excess of A-site Na and K ions. [ABSTRACT FROM PUBLISHER]

Pure Bi6Fe2Ti3O18and vanadium (V) doped Bi6Fe2Ti3O18(Bi5.99Fe2Ti2.75V0.03O18) thin films were prepared on Pt(111)/Ti/SiO2/Si(100) substrates by a chemical solution deposition method. The Bi5.99Fe2Ti2.75V0.03O18thin film exhibited improved electrical and multiferroic properties, such as leakage current densities, dielectric properties, ferroelectric and ferromagnetic properties. We consider that the improved properties might be related to the reduced concentration of oxygen vacancies and the decreased mobility of oxygen vacancies by V doping. [ABSTRACT FROM PUBLISHER]

Multiferroic Bi(Fe0.9Mnx0.1)O3(x= 2+, 3+, and 4+) thin films were prepared on Pt(111)/Ti/SiO2/Si(100) substrates by using a pulsed laser deposition method. The effects of different oxidation states of Mn used as a starting material on crystal structure, leakage current, dielectric, and ferroelectric properties were investigated. No significant change in the crystal structure was observed while electrical properties were affected by the oxidation states of Mn. A frequency-dependent dielectric relaxation region was observed in the films with Mn3+and Mn2+, indicating the presence of space charges such as oxygen vacancies. [ABSTRACT FROM AUTHOR]

Pure Bi5FeTi3O15and its doped compounds, such as Bi4.15La0.75FeTi3O15and Bi4.15Nd0.85FeTi3O15thin films, were prepared on Pt(111)/Ti/SiO2/Si(100) substrates by using a chemical solution deposition method. The crystalline structures and the surface morphologies of the thin films were identified by using an X-ray diffractometry, a Raman spectroscopy, and a scanning electron microscopy. In addition, the comprehensive electrical properties of the thin films, such as ferroelectric hysteresis loops and leakage current densities, were characterized by using a precision materials analyzer and an electrometer at room temperature, respectively. [ABSTRACT FROM AUTHOR]

(Eu, Mn) co-doped bismuth ferrite [(Bi0.9Eu0.1)(Fe0.9Mn0.1)O3 (BEFMO)] thin films were deposited on Pt(111)/Ti/SiO2/Si substrates by using a chemical solution deposition method. The coated films were annealed in N2, air and O2 atmospheres at 550°C for 30 min. Effects of annealing atmosphere on the crystal structure, ferroelectric properties and leakage current density of the BEFMO thin films were investigated. The single-phase rhombohedral perovskite crystal structure of all the samples was confirmed by x-ray diffraction analysis. From the electrical studies, the BEFMO thin film annealed in air atmosphere showed better electrical properties than O2 and N2 atmosphere annealed samples. The largest remnant polarization 96.4 μC/cm2 at an electric field 1060 kV/cm was obtained from the BEFMO thin film annealed in air. [ABSTRACT FROM AUTHOR]

The structural and electrical properties of BiFeO3 (BFO) and rare earth metal ions (Re) co-substituted (Bi0.9Re0.1)(Fe0.9Mn0.1)O3-δ (Re = Nd, Sm, Ce and Tb) thin films prepared on Pt(111)/Ti/SiO2/Si(100) substrates via a chemical solution deposition method were investigated. The significant decrease of leakage current density and improved ferroelectric properties were observed from the co-substituted thin films. The largest remnant polarization (2Pr) (61.7 μC/cm2) and the lowest coercive field (2Ec) 657 kV/cm at 931 kV/cm were measured from the (Bi0.9Ce0.1)(Fe0.9Mn0.1)O3-δ thin film. The leakage current density value of (Bi0.9Sm0.1)(Fe0.9Mn0.1)O3-δ thin film (3.29 × 10−5A/cm2) was found to be two order lower than that of the pure BFO. [ABSTRACT FROM AUTHOR]

Ferroelectric K0.5Bi4.5Ti4O15 (KBTi) and Cr-doped K0.5Bi4.5Ti4O15 ((K0.5Bi4.5Ti3.97 Cr0.03O15-δ), (KBTC)) thin films were prepared on Pt(111)/Ti/SiO2/Si substrates by using a chemical solution deposition method. The thin films were annealed at 750°C for 3 min by a rapid thermal annealing process under oxygen atmosphere. Compared to pure KBTi thin film, there was no structural change while improved ferroelectric and leakage current properties were observed. The values of remnant polarization (2Pr ) and coercive field (2Ec ) were 50.9 μC/cm2 and 244 kV/cm at an applied electric field of 300 kV/cm, respectively. The 2Pr we observed is compatible with that of doped bismuth layer-structured ferroelectric thin films. Leakage current density was 6.00 × 10−7 A/cm2 at 200 kV/cm. The enhanced properties of KBTC could be explained by a defect dipole (Cr′Ti-V) and increased average grain size. [ABSTRACT FROM AUTHOR]

Wide band gap ZnS-ZnO thin films were grown on c-Al2O3 by a pulsed laser deposition method using a pure ZnS target with a fixed substrate temperature of 600°C and a range of oxygen partial background pressures of 5 × 10-5∼50 Torr. With low oxygen deposition pressures, films were found to be mainly ZnS. However, with high oxygen pressures, the deposited thin films were found to be mainly ZnO. The formation of the ZnO films with high oxygen pressure could be attributed to the fast chemical reaction of O and S in the deposition chamber during deposition. It was found that there is a good linear correlation between measured energy band gaps and S/Zn atomic ratio of the films as expected. [ABSTRACT FROM AUTHOR]

Ferroelectric and leakage current behaviors of Zn-Mn co-doped polycrystalline BiFeO3 (BFO) thin films fabricated by a pulsed laser deposition were investigated in comparison with un-doped BFO thin films. Ferroelectric hysteresis loop was observed in Zn-Mn co-doped BFO film capacitor: 2Pr = 109 μC/cm2 and 2EC = 674 kV/cm with maximum electric field of 600 kV/cm. And leakage current was reduced with Zn-Mn co-doping at low electric field region and 10 mol% Bi-excess BFO film has best leakage current behavior in a wide electric field range. [ABSTRACT FROM AUTHOR]

Ferroelectric Na0.5Bi4.5Ti4O15 (NaBTi) thin films, selectively controlled in c-axis and random orientation, were fabricated on a Pt(111)/Ti/SiO2/Si(100) substrate by using a chemical solution deposition method. The preferred orientation of the thin films annealed at 750°C under oxygen atmosphere was confirmed by X-ray diffraction and scanning electron microscope studies. We found that ferroelectric, dielectric, and leakage current properties were strongly related to the crystallographic orientation of NaBTi thin films; the randomly oriented NaBTi thin film exhibited better properties than the c-axis oriented thin film. The values of remnant polarization (2Pr), dielectric constant, and leakage current density were 21 μC/cm2 at 300 kV/cm, 630 at 100 kHz, and 7.4 × 10-6 A/cm2 at 100 kV/cm for the randomly oriented thin film, respectively, and 6 μC/cm2, 420, and 1.1 × 10-1 A/cm2 for the c-axis oriented thin film, respectively. Also, no polarization fatigue was observed in both NaBTi thin films up to 107 switching cycles. [ABSTRACT FROM AUTHOR]

Ferroelectric CaBi4Ti4O15 (CBTi) thin films with random orientation and high c-axis orientation were prepared on a Pt(111)/Ti/SiO2/Si(100) substrate by a chemical solution deposition method. We observed a strong dependence of ferroelectric and dielectric properties on the film orientation. The CBTi thin film with random orientation exhibited remnant polarization (2Pr) of 54 μ C/cm2 at an applied electric field of 250 kV/cm and dielectric constant (ε) of 412 at a frequency of 1 kHz. The values of 2Pr and ε were larger than those observed in the CBTi thin film with high c-axis orientation. In addition, the randomly oriented thin film showed lower leakage current density than the highly c-axis-oriented thin film. [ABSTRACT FROM AUTHOR]

SrBi5FeTi4O18 (SBFT) thin films were prepared on a Pt(111)/Ti/SiO2/Si(100) substrate using a chemical solution deposition method and annealed at 650°C under oxygen atmosphere. It was found that the polycrystalline SBFT thin film exhibits good ferroelectric properties. The values of remnant polarization (2Pr) and coercive electric field (2Ec) were 33 μ C/cm2 and 150 kV/cm at an applied electric field of 250 kV/cm, respectively. Leakage current density of the thin film was 106 A/cm2 at 100 kV/cm. The values of dielectric constant and dielectric loss were 470 and 0.05 at 1 kHz, respectively. No significant polarization fatigue was observed up to 1.44 × 1010 switching cycles. Also weak ferromagnetic properties were observed. [ABSTRACT FROM AUTHOR]

Thermal stability of Ta films grown on Si(100) was investigated by in situ x-ray scattering and ex situ cross-sectional transmission electron microscopy. As a Ta/Si(100) film was annealed at around 500 °C, a uniform Ta–Si interlayer was formed at the interface. This interlayer acts as a diffusion barrier. The Ta film with the interlayer is thermally stable up to 700 °C. Meanwhile, Ta films directly annealed to above 640 °C exhibit no interlayer formation and transform to randomly nucleated tantalum-silicide phases. Maintaining a uniform interlayer is a critical factor for enhancing thermal stability of Ta/Si(100) films. [ABSTRACT FROM AUTHOR]

5 mol % La3 +, Nd3 + or Y3 +-cosubstituted BiFe0.97Cr0.03O3 thin films (denoted by BLaFCr, BNdFCr, and BYFCr, respectively) have been successfully deposited on Pt (200)/TiO2/SiO2/Si substrates by a chemical solution deposition method. Well-saturated ferroelectric hysteresis loops and low leakage current densities have been observed in BLaFCr, BNdFCr, and BYFCr thin films with single-phase structure. The values of remanent polarization (Pr) and coercive field (Ec) were 64 μ C/cm2 and 275 kV/cm, 61 μC/cm2 and 290 kV/cm, and 31 μ C/cm2 and 315 kV/cm for BLaFCr, BNdFCr and BYFCr thin films at the maximum electric field of 712 kV/cm, respectively. In the present study, the differences in values of Pr seem to be related to the doped ionic radii. [ABSTRACT FROM AUTHOR]

Cu-doped Ba0.7Sr0.3TiO3 (BST) thin films were prepared on Pt(111)/Ti/SiO2/Si(100) substrates by a sol-gel spin coating process. The coated thin films were annealed at 750°C for 3 min in oxygen, air and nitrogen atmospheres by a rapid thermal annealing process. All of the Cu-doped BST thin films were consisted of a single phase perovskite structure and exhibited smooth crack-free surfaces. We investigated the effects of the annealing atmosphere on the microstructure and the electrical properties of the Cu-doped BST films. The Cu-doped BST film by annealing in oxygen exhibits a dielectric constant of 923 with electric field dependent tunability of 48.6% at electric field 250 kV/cm and a leakage current density of 1.82 × 10- 5A/cm2 at electric field of 150 kV/cm. [ABSTRACT FROM AUTHOR]

Neodymium-substituted Bi4Ti3O12 (BNdT) thin films were prepared by a chemical solution deposition technique on platinum- coated silicon substrates. All of the samples were annealed at the relatively low temperature of 600 °C by a rapid thermal annealing process in different atmospheres, such as O2, air, and nitrogen, and vacuum. Irrespective of different annealing atmospheres, all of the BNdT thin films exhibit good ferroelectric properties, such as a saturated hysteresis loop, good fatigue endurance, and low leakage current density. A large remanent polarization (Pr) of ∼48 μC/cm2 with an electric field of 240 kV/cm was observed from the BNdT thin film annealed in O2 atmosphere. The BNdT thin films annealed in nitrogen and vacuum, at reduced oxygen partial pressures, exhibit smaller Pr than that annealed in oxygen. The difference of Pr of the BNdT thin films annealed in different atmospheres may originate from differences in the grain sizes and the number of oxygen vacancies. [ABSTRACT FROM AUTHOR]

A new type of bismuth-based relaxor, such as Bi 2 (Y 1/2 Nb 1/2 ) 2 O 7 and Bi 2 (Mg 1/3 Nb 2/3 ) 2 O 7 thin films were fabricated on Pt/Ti/SiO 2 /Si substrate by a sol-gel spin coating process. The films exhibit characteristic diffused phase transition. The temperature dependent reciprocal dielectric constant characteristics of the films deviates from the Curie-Weiss law in the temperature range over the dielectric constant maximum temperature ( T m ). The diffuseness of the phase transition of the thin films was estimated by calculating the difference between T m and T cw (starting temperature following the Curie-Weiss law). For the thin films annealed at 750°C, the temperature T m , the Curie-Weiss temperature Θ, the Curie-Weiss constant c and the temperature T cw were measured at frequency of 10 3 Hz, respectively. [ABSTRACT FROM AUTHOR]

Nd-substituted bismuth titanate Bi3.54Nd0.46Ti3O12 (BNT) thin films were prepared on (111)Pt/Ti/SiO2/Si substrates by a sol–gel method. The BNT thin films processed at a low annealing temperature of ∼600 °C showed good ferroelectric properties. The randomly oriented BNT single phases and the improved ferroelectric properties were confirmed by X-ray diffraction and polarization–electric field hysteresis loops, respectively. The remanent polarization of the BNT thin films is 64 μC/cm2, which is larger than that of Bi3.25La0.75Ti3O12 (BLT) thin films. After 1010 read/write switching cycles, the effective non-volatile charges showed no polarization fatigue. Regardless of the low annealing temperature of 600 °C, the BNT thin films had good ferroelectric properties with high remanent polarizations and strong fatigue resistances. [ABSTRACT FROM AUTHOR]

The formation of phase-pure BiFeO 3 (BFO) thin films using a chemical solution deposition on platinium electrode has been investigated systematically by changing the annealing condition of the films. From the X-ray diffraction results, it was found that the formation of the phase-pure BFO was favorable under lower oxygen partial pressure, slower heating rate and Pt(200)/Ti/SiO 2 /Si(100) substrate. The remanent polarization ( P r ) and coercive field ( E c ) values of the phase-pure BFO thin film annealed at 600°C in nitrogen atmosphere by conventional furnace annealing method are approximately 0.9 μC/cm 2 and 20 kV/cm, respectively. [ABSTRACT FROM AUTHOR]

Well c-axis oriented 320 nm and 160 nm thick ZnO thin films were deposited with pulsed laser deposition on Pt/Ti/SiO 2 /Si(100) substrates. Diode characteristics of Au/ZnO/Pt in electrical conductivity were observed. The conductivity in forward bias was sensitive to the hydrogen annealing but almost insensitive in reverse bias. The conductivity of 320 nm thick film in forward bias increased from 6.1 × 10 -5 Ω -1 cm -1 in as-deposited film to 3.3 × 10 -3 Ω -1 cm -1 in hydrogen annealed one at 200 &circle; C. The observed dielectric constant 70 was much higher than that of ceramic ZnO. Dielectric anomaly at about 1 kHz was observed and attributed to the space charge. [ABSTRACT FROM AUTHOR]

Lanthanides (La3+, Nd3+, Sm3+ and Eu3+) doped Bi4Ti3O12 (BIT) films fabricated on p-type Si(100) substrates by a sol-gel spin coating process. The films were characterized by X-ray diffractometer and scanning electron microscope. Memory windows calculated from the measured C-V hysteresis curves were approximately 3.5, 0.85, 0.8, and 0.54 V for La-, Nd-, Sm-, and Eu-doped BIT films with a sweep voltage of ± 10 V, respectively. The effects of lanthanides substitution for Bi3+ in the perovskite layer on the electrical properties, such as C-V and I-V characteristics, have been reported. [ABSTRACT FROM AUTHOR]

Zinc oxide thin films were grown on sapphire substrates by metal organic chemical vapor deposition technique. Single crystal films with flat and smooth surfaces were reproducibly obtained, with application of sample bias and O2 inductively coupled plasma (ICP). At the growth condition of 650 °C, 400 W ICP power, -94 V bias voltage and O/Zn ratio of 75, full width at half maximum values of room temperature photoluminescence and high-resolution x-ray diffraction were measured to be 126 meV and 269 arc sec, respectively. It was proposed that application of sample bias provided reactant ions with kinetic energy, which promoted formation of single crystalline films. [ABSTRACT FROM AUTHOR]

The tuning properties of epitaxial Ba[sub 0.5]Sr[sub 0.5]TiO[sub 3] (BST) thin films were investigated by a scanning microwave microscope (SMM) and an LCR meter. Although the BST films on LaAlO[sub 3] and MgO substrates showed similar tuning behavior when measured by the LCR meter at 1 MHz, remarkably different tuning properties were observed in the planar capacitors measured by SMM. The BST films on LaAlO[sub 3] substrates were hardly tuned when measured by SMM, while the BST films on MgO showed significant tuning behavior between the electrodes. We attribute these different tuning properties to the anisotropic tuning caused by the strain in BST films. This will enable the design of much improved tunable devices while minimizing the loss associated with the dielectric. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Photoluminescence (PL) and cathodoluminescence (CL) of light emitting diode samples with various InGaN/GaN multi-quantum-well (MQW) active structures and a range of dislocation density (∼7×108/cm2 to ∼9×109/cm2) were investigated. Results indicate that threading dislocations have impact on the luminescence of GaN thin films and act as a nonradiative recombination center. It was also observed that the optical emission is affected by MQW structure such as the number of quantum wells. [Copyright &y& Elsevier]