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We prepared colossal magnetoresistive La0.8Sr0.2MnO3 thin films on the MgO, SrTiO3 and LaAlO3 single crystal substrates using KrF excimer pulsed laser ablation technique. The structural and electrical properties of the La0.8Sr0.2MnO3 thin films which were strained by the lattice mismatch are reported. The in-plane lattice mismatch between the La0.8Sr0.2MnO3 and MgO, SrTiO3 and LaAlO3 substrates are -7.8 %, -0.5 % and +2.3 %, respectively. The X-ray diffraction spectra of the films exhibited c-axis orientation. In the case of the La0.8Sr0.2MnO3 / LaAlO3 thin films with thickness over 100 nm, the divided (00l) peaks were observed. The surface morphology and transport property of the strongly stressed La0.8Sr0.2MnO3 / LaAlO3 were different from those of La0.8Sr0.2MnO3 / MgO and La0.8Sr0.2MnO3 / SrTiO3thin films.
Characteristics of laser-ablated carbon plasma and properties of diamond-like carbon film in KrF pulsed laser deposition were investigated using laser-induced fluorescence (LIF) and optical emission spectroscopy. Two-dimensional LIF images of C2 (Swan band, d3Φg – a3Φu) and C3 (Comet Head System, A1Φu –X1Σg+) molecules were detected as a function of laser energy density by narrow band pass filters and an intensified CCD camera. C2 LIF intensity is found to be weaker in the central part of the plume than that at the periphery at incident energy greater than 6 J/cm2. It is conjectured that C2 molecules are dissociated by collision with energetic species in the central part of the ablation plume, and degrade the diamond-like property of deposited films.
Results are presented of a study on the mechanical stress dependence of the resistance of polycrystalline silicon (Poly-Si) films, doped with different atomic species. Two types of Poly-Si film implanted with boron and phosphorus ions were studied, namely, B-doped films of 400 nm and P-doped layers of 250 nm thickness, which were deposited by LPCVD at 620 °C on thermally oxidized silicon wafers. Film doping was done by ion implantation at 50 keV, with a dose of boron and phosphorus of 2 × 1014 and 5.3 × 1014 cm−2, respectively. The Poly-Si films were annealed in a H2 ambient at 1000 °C for 20 min to activate the implanted atoms. A controlled amount of external stress was applied to the silicon wafers in order to study the impact on the electrical performance of the implanted Poly-Si resistors. The resistance of the B-doped Poly-Si films is shown to increase by the mechanical stress, while the resistance of the P-implanted Poly-Si films remained unchanged. It is concluded that this difference is related to the structural differences between Poly-Si films implanted with boron and phosphorus, respectively.
The Au / PbZrxTi1-xO3 (PZT) ferroelectrics / YBa2Cu3O7-x (YBCO) superconductor / yttria-stabilized zirconia (YSZ) heterostructures were prepared on Si (100) substrate by KrF excimer laser ablation technique. The x-ray diffraction patterns showed that the PZT films prepared on YBCO / YSZ /Si at 550°C, O2 100 mTorr and a laser energy density of 2 J/cm2(5Hz) are pure perovskite and highly oriented with the (00l) orientation. The polarization (P)-electric field (E) characteristics showed the remanent polarization Pr of 23 µC/cm2 and coercive field Ec, of 35 kV/cm. Pr of the PZT capacitor degraded to one half of initial value after about 1010 switching cycles (50 kHz).
We have fabricated epitaxial PbZr0.52Ti0.48O3 (PZT, 40~1200 nm)/YBa2Cu3O7-x (YBCO, 400 nm) film ferroelectric/superconductor heterostructures on the single-crystal neodymium doped yttrium monoaluminate [YAlO3+1%Nd2O3] and MgO substrates by KrF pulsed laser deposition technique. The dielectric constant of 950 and loss tangent δ of 0.04 have been found to be frequency independent in the range 100 Hz to 100 kHz while electric resistivity ρ (150 kV/cm) is of 6×1011 Ω·cm, remnant polarization and coercive field are 32 μC/cm2 and 43 kV/cm, respectively. Fast ferroelectric switching kinetics with characteristic switching time around 50 ns has been observed. Universal electric field and temperature dependencies of switching time as well as film thickness dependence of coercive electric field have been observed and correspond to ferroelectric needle-like domain switching.
The perovskite oxide YBa2Cu3O7-x (YBCO) and Pb(ZrxTi1-x)O3 (PZT) thin films have been deposited for superconducting-ferroelectric devices. KrF excimer laser ablation technique was used at the deposition conditions of 200-600mTorr O2, 2-3J/cm2 and 5-10 Hz operation frequency. Heterostructures of PZT-YBCO-YAlO3:Nd show the zero resistivity critical temperature of 82K and excellent ferroelectric properties of remnant polarization 32 μC/cm2, coercive force of 80kV/cm and dielectric constant 800. Cycling fatigue characteristics and leakage current are also discussed.
Dynamics of carbon ablation plasma plume during the preparation of diamond-like carbon films by KrF excimer pulsed laser deposition was investigated using laser induced fluorescence (LIF) and optical emission spectroscopy. LIF signal from C2molecule (Swan band, d 3Φg – a3Φu) was detected using a photomultiplier tube and an intensified CCD camera. Temporal evolution and spatial distribution of C2 molecules in the ablated plume were measured as a function of laser energy density and ablation area. LIF intensity is found to be weaker in the central part of the plume than that at the periphery at incident energy greater than 6 J/cm2. It is conjectured that some of C2molecules are dissociated by collision with energetic species in central part of the ablation plume. Dynamics of ablation plasma plume is strongly dependent on the size of ablated area.
Epitaxial PbZr0.52TiO0.48O3/YBa2Cu3O7−x heterostructures on Nd:YAlO3 and MgO substrates were fabricated by KrF pulsed laser deposition. The coercive electric field of the PZT films increased with decrease of the film thickness from 1.2 μm to 0.04 μm, while the magnitude of spontaneous polarization was almost constant in this thickness range. It was found that the dependence of the film thickness d on the coercive electric field Ec was Ecæ d−2/3. This results from that the PZT/YBCO heterostructure has the one dimensional ferroelectric domain growth without non-ferroelectric phase. The polarization of AuIPZT/YBCO/(MgO or YAlO) capacitors can be changed by the applied voltage below 5 V.
The colossal magnetoresistive La0.8Sr0.2MnO3 (LSMO) thin film was prepared on the MgO (100) single crystal substrate using KrF excimer pulsed laser deposition technique. The LSMO film deposited at the substrate temperature of 850 °C, oxygen pressure of 500 mTorr and laser energy density of 2 J/cm2(5 Hz) showed the resistivity peak temperature (Tp) of 330 K and the magnetoresi stance change of 15 %(H=0.7 T) at the room temperature. The large lattice mismatch with the substrate increased Tp and decreased the resistivity of the LSMO film.
The X-ray diffraction measurement for the PbZr0.52Ti0.48O3 (PZT) / LSMO heterostructures indicated both c-axis and in- plane orientation, with the good PZT surface morphology.
We developed an immunoglobulin G (IgG) enzyme-linked immunosorbent assay (ELISA), using partial recombinant nucleoproteins (rNP) of Reston Ebola virus (EBO-R) and Zaire Ebola virus (EBO-Z). We examined the reaction of 10 sera from cynomolgus macaques naturally infected with EBO-R to each of the partial rNP in the IgG ELISA. All the sera reacted to the C-terminal halves of the rNP of both EBO-R and EBO-Z. Most of the sera reacted to the RΔC (amino acid (aa) 360–739), and RΔ6 (aa 451–551) and/or RΔ8 (aa 631–739) at a higher dilution than to the corresponding truncated rNPs of EBO-Z. The results indicate that this IgG ELISA is useful for detecting EBO-R specific antibody, and may have a potential to discriminate EBO-R infection from other subtypes.
Results are presented of a study on the mechanical stress dependence of the resistance of polycrystalline silicon (Poly-Si) films doped with different atomic species. Two types of Poly-Si film implanted with boron and phosphorus ions were studied, namely, B-doped films of 400 nm and P-doped films of 250 nm thickness, which were deposited by low-pressure chemical vapor deposition at 620 °C on thermally oxidized silicon wafers. The film doping was done by ion implantation at 50 keV, with a dose of boron and phosphorus of 2 × 1014 and 5.3 × 1014 cm−2, respectively. The Poly-Si films were annealed in a N2 ambient at 1000 °C for 20 min to activate the implanted atoms. A controlled amount of external stress was applied to the silicon wafers to study the impact on the electrical performance of the implanted Poly-Si resistors. The resistance of the B-doped Poly-Si films is shown to increase by the mechanical stress, while the resistance of the P-implanted Poly-Si films remained unchanged. It is concluded that this difference is related to the structural differences between Poly-Si films implanted with boron and phosphorus, respectively.
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