bluuebunny/crossref_metadata_2025_split huggingface dataset:
A New Hybrid Pvd/Omcvd Route to High‐Tc Superconducting Thin Films of Tl‐Ba‐Ca‐Cu‐O
Authors: Richeson D. S. , Tonge L. M. , Wang X. K. , Marcy H. O. , Marks T. J. , Ketterson J. B. , Chang R. P. H. , Kannewurf C. R. 
Published: March 2011

AbstractSuperconducting thin films of Tl‐Ba‐Ca‐Cu‐0 have been prepared by a unique hybrid technique that combines electron beam evaporation with organometallic chemical vapor deposition (OMCVD). Multilayer thin films of Ba‐Ca‐Cu‐O are prepared by sequential electron beam evaporation of BaF2, CaF2, and Cu sources onto single crystal MgO (100) or yttria‐stabilized zirconia (YSZ) substrates followed by annealing in a water vapor‐saturated oxygen atmosphere. Thallium is then incorporated into these films in either of two ways: (1) via OMCVD using thallium(cyclopentadienide) as the source, or (2) rapid annealing of the Ba‐Ca‐Cu‐O film in the presence of bulk thallium superconductor. The resultant films primarily consist of single phase TlBa2Ca2Cu3Ox with the Cu‐O planes preferentially oriented parallel to the substrate surface. Resistivity measurements indicate superconducting onset temperatures above 120 K with zero resistance by 104 K. By eliminating the water vapor anneal, residual fluoride, originating from the sources, may be left in the film. This leads to formation of predominantly c‐axis oriented crystallites of the TlBa2CaCu2Ox phase.
Routes to High‐Tc Superconducting Tl‐Ba‐Ca‐Cu‐O Films Using Organometallic Chemical Vapor Deposition
Authors: Richesonw Darrin S. , Tonge Lauren M. , Zhao Jing , Zhang Jiming , Marcy Henry O. , Marks Tobin J. , Wessels Bruce W. , Kannewurfcc'd Carl R. 
Published: March 2011

AbstractFilms of the Tl‐Ba‐Ca‐Cu‐O high‐Tc superconductor can be prepared by several organometallic chemical vapor deposition routes. Two of these involve Ba‐Ca‐Cu‐0 films that are first prepared using the volatile metal‐organic precursors Ba(heptafluorodimethyloctanedionate)2, Ca(dipivaloylmethanate)2, and Cu(acetylacetonate)2‐ Deposition is carried out at a pressure of 5 Torr with argon as the carrier gas and water vapor as the reactant gas. Thallium is next incorporated into these films either by organometallic chemical vapor deposition using Tl(cyclopentadienide) as the source, or by vapor diffusion using bulk Tl‐Ba‐Ca‐Cu‐O as the source. Thallium deposition is carried out at atmospheric pressure with an argon carrier and water‐saturated oxygen reactant gas, followed by rapid thermal annealing. Both procedures yield films that consist primarily of the TlBa2Ca2Cu3Ox phase, have preferential orientation of the Cu‐O planes parallel to the substrate surface, and exhibit onset of superconductivity at ∼125 K with zero resistance by 100 K.
Effect of Glow Discharge Current on Composition of Y‐Ba‐Cu‐0 Films by High Pressure Dc Sputtering Process
Authors: Lin R.J. , Chen Y.C. , Wu P.T. 
Published: March 2011

AbstractThe Y‐Ba‐Cu‐0 (YBCO) films were grown on (100)Mg0 substrate by the high pressure DC diode sputtering process. The targets were YBCO compounds made by solid‐state reaction. The sputtering gas was Ar‐50%02, and total pressure was 1.5 torr. As‐deposited superconducting YBCO films can be prepared at low substrate temperature at high discharge current. For Y1Ba2Cu30x target, the atomic ratio Ba/Y in the films almost remains constant (Ba/Y = 1.7) and Cu content monotonically increases with increasing discharge current. The Cu content in the film approaches to that of the target at low discharge current. Concentrations of 0 and 02+ in plasma markedly increase during increase of discharge current. High Cu content at large discharge current may be caused by action of electrical field on Ba+ and Y+.
The Transport Properties and Defect Chemistry of La2-XSrXCuO4-δ
Authors: Tsai Ming-Jinn , Opila Elizabeth J. , Tuller Harry L. 
Published: March 2011

AbstractLa2‐xSrxCuO4‐δ has been studied to determine the role of dopants and oxygen stoichiometry on the transport properties and defect chemistry of this system. The conductivity was found to reach a maximum for 0.2 < x < 0.3 which reflects a change from electronic to ionic compensation of the Sr dopant at large values of x. A metal to semiconductor transition is observed for x > 0.6 for temperatures below ∼ 600°C. However, the source of this behavior is not clear, given that an increasing amount of second phase was observed for x > 0.4. The conductivity and thermoelectric power (TEP) of La2CuO4 show a Po2⅙ dependence and a temperature independence, implying that the hole mobility is not thermally activated and the enthalpy of oxidation is nearly zero. This last conclusion is confirmed by TGA data.
As‐Grown Superconductivity of Bi‐System Thin Films Prepared by Magnetron Sputtering with Three Pb Doped Targets: (Bi 1.6 Pb0.4) 1 + a (SrCa)2 Cu3 O x, (Bi 1.6 Pb0.4) 1 (SrCa)2+c Cu3 Ox and (Bi 1.6 Pb0.4) 1 (SrCa)2Cu3+cOx (a = 0.5, b= 1,c= 1.5)
Authors: Kuroda Ken'ichi , Tanioku Masami , Kojima Kazuyoshi , Hamanaka Koichi 
Published: March 2011

AbstractSuperconducting Bi system thin films have been formed on MgO(100) substrates by RF magnetron sputtering from three Pb‐doped targets: Bi2.4 Pb0.6 Sr2 Ca2 CU3 O x ,Bi 1.6 Pb0.4 Sr3 Ca3 CU3 O x and Bi 1.6 Pb 0.4 Sr2 Ca2 CU4.5 O x. The as‐grown films formed at substrate temperatures above 600 °C showed superconductivity, though, they did not contain Pb.
The film, formed at 660°C and kept at the same substrate temperature and gas pressure as the sputtering conditions for 5 h after deposition, showed a resistivity drop at 115 K and zero resistivity at 83 K. The Jc value of the film was 4x105 A/cm2 at 77 K and 3x107 A/cm 2 at 20 K.
Metal‐Organic Decomposition and Microstructure Development in Ba2ycu3o7‐X Films from Metal Trifluoroacetate Precursors
Authors: Mcintyre Paul C. , Chiu Raymond C. , Cima Michael J. , Rhine Wendell E. 
Published: March 2011

AbstractDecomposition of metal‐organic precursors to Ba2Ycu3O7‐X films is difficult because of the high reaction temperature required to decompose the BaCO3 intermediate. The recently proposed use of metal trifluoroacetate (TFA) solutions offers an alternative path to barium‐containing superconducting films. The TFA salts decompose to the metal fluorides forming BaF2, eliminating BaCO3 from the system. Ultimate conversion to BYC, however, is shown not only to depend on hydrolysis of the BaF2 at high temperatures, but also hydrolysis of copper trifluoracetate at low temperatures to prevent the volatilization of Cu(TFA)2. These processes result in unique microstructural behavior which can be characterized by electon microscopy and Auger spectroscopy. Effects due to substrate interactions have been eliminated by use of a chemically inert substrate material, BaZrO3.
Electrophoretic Deposition of High-Temperature Superconductor Thick Films
Authors: Mooney J. B. , Sher A. , Riggs M.L. , Sabo K.A. , Rosengreen A. , Kingsley B. , Terry J.C. 
Published: March 2011

AbstractThick films of high-temperature superconductors have been deposited electrophoretically using techniques developed for office copier toning. The resultant films are dense because of the high charge density per particle and the high fields during deposition. Orientation by electrostatic and magnetic fields has been demonstrated.
High Resolution Transmission Electron Microscopy Study of Defect Structures in Mixed-Phase YBaCuO
Authors: Fendorf M. , Kvam E. , Gronsky R. 
Published: March 2011

AbstractMixed-phase superconducting YBaCuO is characterized by means of high-resolution transmission electron microscopy. This technique reveals that such material contains numerous crystallographic defects of various types. Several of these are described in detail, and their origins discussed.
Domain Structures and Pinning in Oxide Superconductors
Authors: Roytburd Alexander L. 
Published: March 2011

AbstractThe domain structure of oxide superconductors arises as a result of twinning associated with the tetragonal-orthorhombic transition inside a restricted volume (a grain in a polycrystal, an epitaxial layer, or a part of an initial single crystal). A thermodynamic theory of the size and arrangement of the domains has been developed. There are two types of interfaces in equilibrium domain structures: coherent twin boundaries and boundaries between polytwin layers with microstresses. Elastic vortex-interface interactions have been estimated.
Oriented Microstructure of Ybco Thick Films
Authors: Wellhofer F. , Shields T.C. , Abell J.S. , Taylor K.N.R. 
Published: March 2011

AbstractThe surface morphology and internal structure of a superconducting screen printed thick film of YBCO has been examined by means of optical and scanning electron microscopy. The highly textured track was sintered at a temperature above the peritectic temperature of the 123 phase, and the resulting characteristic spherulitic morphology has been found to be associated with underlying elongated strands of CuO. The composition of the inter‐diffusion layer formed at the film/substrate boundary is consistent with a Ba(Zr,Cu)O3 solid solution with small concentrations of yttrium.
Effect of High Temperature Deformation on Grain Boundary Defects in Yba2Cu3O7-X
Authors: Garcia R. , Misiolek W.Z. , Wright R.N. , Rajan K. 
Published: March 2011

AbstractThe results of transmission electron microscopy studies on YBa2Cu3O7‐x subjected to high temperature extrusion are presented. Particular emphasis is put on high temperature accommodation processes of lattice dislocations into sub‐grain boundaries. It is suggested from the electron microscopy observations that stress induced climb mechanisms for dislocations are operative. Also presented is evidence of localized lattice distortions near twin boundaries due to isothermal high temperature deformation. Preliminary results on the structure of grain boundary facets and steps is described. The implications of these results for texture development in bulk ceramic superconductors is also discussed.
Vortex Structure: Lattice, Glass, or Liquid?
Authors: Soulen Robert J. , Wolf Stuart A. 
Published: March 2011

AbstractRecent measurements of the dissipation in cuprate superconductors in a magnetic field have been interpreted as providing evidence for the presence of new phases in type II superconductors: flux liquids or flux glasses. We suggest that a more conventional interpretation in terms of the electrodynamics of vortices can adequately account for all the observations. Based on this model, we propose a magnetic phase diagram.
High Critical Current Density in Ultrathin Ybco Films
Authors: Xi X.X. , Schauer W. , Windte V. , Meyer O. , Linker G. , Li Q. , Geerk J. 
Published: March 2011

AbstractMeasurements of the critical current density Jc for ultrathin YBa2Cu307‐X (YBCO) films are presented.A high Jc value at 77K in zero field of 2xl06A/cm2 was obtained in a 30nm thick film and even a 5nm thick film could carry a supercurrent of 3.5x105 A/cm2 at 4.2K in zero field. A very weak field‐dependence of Jc was observed when the field was in the (a,b) plane showing greatly depressed dissipation.
Electrical Transport Dissipation Effects in Epitaxial Y1ba2cu3o7.X Thin Films
Authors: Christen D. K. , Klabunde C. E. , Feenstra R. , Lowndes D. H. , Norton D. , Kerchner H. R. , Thompson J. R. , Sekula S. T. , Budai J. D. , Boatner L. A. , Narayan J. , Singh R. 
Published: March 2011

AbstractThe electrical transport properties of a series of Y1Ba2Cu307.x thin films deposited onto single crystal substrates by thermal coevaporation and laser ablation were investigated. For fully epitaxial, c‐oriented films on (001) substrate surfaces, the critical current density Jc showed large high‐field enhancements for the film aligned with H parallel to the copper‐oxygen planes. With H||c, a precipitous decay of Jc with increasing field is described by thermally activated flux motion. Films on (110) SrTiO3 substrates were comprised of finely‐divided arrays of grains having [110], and <103>‐type orientations, and exhibited granular behavior. For these “triaxial” films, the transport dissipation was also thermally activated but with much smaller energy barriers.
Thin Film Deposition and Transport in 2223 Bi‐Sr‐Ca‐Cu‐O
Authors: Kucera J.T. , Steel D.G. , Face D.W. , Graybeal J.M. , Orlando T.P. , Rudman D.A. 
Published: March 2011

AbstractWe have reproducibly prepared thin films of Bi‐Sr‐Ca‐Cu‐O with Tc ≥ 105K. Depositions were done at ambient temperature with a subsequent post‐deposition anneal, and did not include lead substitution. X‐ray diffraction data indicates a majority fraction of the 2223 phase. These films possess very large grains of the order of 20‐30 u.m in size. Post‐deposition annealing conditions are a sensitive function of composition. Detailed transport measurements as a function of temperature and magnetic field have been obtained.
Easily Activated Flux Creep and Anisotropic Fluctuation in Ndcecuo Thin Films
Authors: Hatta S. , Hayashi S. , Adachi H. , Wasa K. 
Published: March 2011

AbstractThe diamagnetic properties of NdCeCuO films with electron carriers were studied. The,critical current density ( Jc ) was calculated to be 0.73 x 106 A/cm2 . These films indicated the very strong magnetic relaxation with small activation energy, the significant resistive broadening in the critical region and the largely fluctuated diamagnetization. These results suggested the very weak pinning forces to cause the easily activated flux motion in these specimens.
Correlations Between the Cu‐O Bonding States and the Superconductivity ‐ an Xps Investigation
Authors: Han S.C. , Liu D.Z. , Xie X.M. , Wu Z.L. , Huth G.C. 
Published: March 2011

AbstractAuger electron spectroscopy (AES) and core‐level x‐ray photoelectron spectroscopy (XPS) have been used to study the compositional and electronic‐state variations from the contaminated surface layer to the inner region of YBa2Cu3Ox and Bi2(Sr,Ca)n+1Cun02n+4 compounds. The results showed that the carbon‐rich contamination layer in BSCCO is thin and easier to be removed by Ar+ sputtering, indicating a much more stable surface than that of YBCO. This layer is oxygen deficient and contains higher Cu2+ satellites ( 2p3d9 final states) than in the bulk materials. Line‐shape analysis suggests three‐Gaussian features for both Cu 2p3/2 and O Is lines. The 529 eV signal is observed in both YBCO and BSCCO O Is spectra.
Large Enhancement of JC in YBacuo Single Crystals Induced by Proton Irradiation
Authors: Civale L. , Marwick A.D. , Mcelfresh M.W. , Malozemoff A.P. , Holtzberg F. 
Published: March 2011

AbstractWe have used magnetization measurements to study the effect of proton irradiation on the critical current density of a YBaCuO single crystal. We have obtained a maximum value of 1.5x105 A/cm2 at 77 K and 1 T at a fluence of 2 x 1016 cm-2, representing a 50-fold increase with respect to the unirradiated sample.
Flux Pinning and Weak Link Structure in Ca2Cu1O3 Doped LnBa2Cu3O7-y (Ln=La and Y)
Authors: Mizuno F. , Masuda H. , Hirabayashi I. , Tanaka S. 
Published: March 2011

AbstractFlux pinning and weak link structure were studied on the effect of Ca doping in LnBa2Cu3O7-y system (Ln=La and Y). The magnitude and the magnetic field dependence of the critical current density were improved by Ca doping. A small amount of impurity phase of such as Ca2Cu1O3 may work as a desirable flux pinning center. Moreover, it was found that the current-temperature characteristics for Ca-doped samples showed the evidence of two kinds of superconducting phases which have different transition temperature Tc and Tc'. The experimental result agrees well with the Ambegaokar-Baratoff theory for asymmetric Josephson junctions (S-I-S') in the temperature range of T < Tc' and with the proximity junction theory (S-N-S) in the range of Tc'<T<Tc.
Electron Tunneling into Single Crystals of YBa2Cu3O7-δ
Authors: Valles J. M. , Gurvitch M. , Cucolo M. , Dynes R. C. , Garno J. P. , Schneemeyer L. F. , Wasczcak J. V. 
Published: March 2011

AbstractWe have fabricated tunnel junctions between chemically etched single crystals of YBa2Cu3O7-δ and evaporated metal counterelectrodes which exhibit reproducible characteristics. Above the bulk critical temperature of YBa2Cu3O7-δ, Tc, the conductance, G(V), has a linear dependence with voltage and has some asymmetry. Below Tc, additional structure associated with the superconductivity appears in G(V). At T>>Tc there is a reproducible finite zero bias conductance.
Proximity-Effect and Tunneling in YBa2Cu3O7/Metal Layered Structures
Authors: Greene L. H. , Feldmann W. L. , Barrier J. B. , Farrow L. A. , Miceli P. F. , Ramesh R. , Wilkens B. J. , Bagley B. G. , Giroud M. , Rowell J.M. 
Published: March 2011

AbstractSuperconducting thin films of YBa2Cu3O7 are prepared in-situ by on-axis, sputter deposition from a single, composite target. Our planar magnetron target composition of Y:Ba:Cu = 1.08:1.76:4.5 sputtered onto MgO at T~750°C in a 600mTorr Ar-O2 atmosphere yields reproducible superconducting films having Tc(R = 0)>80K and stoichiometry 1:2:3, that are shiny and of near epitaxial, crystalline quality. In order to ensure clean interfaces, YBa2Cu3O7/normal metal bilayers (to form SNS' Josephson junctions) and YBa2Cu3O7/normal metal/insulating barrier trilayers (to form SNIS' proximity tunnel junctions) are grown completely in-situ. (The S' = Pb counter electrode is evaporated ex-situ.) A supercurrent and Shapiro steps are observed in microwave irradiated SNS' (N = Ag) small area (5x10-5cm2) junctions. In SNIS' tunnel junctions, high-quality Pb tunneling is observed.
Selective Mn Doping of Thin Film Zns:Mn Electroluminescent Devices by Laser Photochemical Vapor Deposition
Authors: Kitai A. , Wolga G.J. 
Published: March 2011

ABSTRACTU.V. laser radiation from a krypton ion laser was used to dissociate manganese carbonyl [Mn2 (CO)10*] at the surface of a ZnS thin film. The resulting Mn deposit was thermally diffused into the film to form a ZnS:Mn thin film electroluminescent (TFEL) device with spatially selective Mn doping. Process parameters and techniques are described as well as electroluminescence measurements on display elements. Finally we suggest applications of this process to future TFEL displays.
Laser Spectroscopic Investigation of Gas-Phase Processes Relevant to Semiconductor Device Fabrication
Authors: Karlicek R. F. , Donnelly V. M. , Johnston W. D. 
Published: March 2011

ABSTRACTChemical vapor deposition (CVD) and plasma etching are important gas-phase techniques used in fabricating semiconductor devices. These processes frequently involve poorly understood multicomponent gas-phase reactions which control reproducibility and product quality. Laser spectroscopic techniques have recently been developed to investigate CVD and plasma etching. These methods offer several advantages for probing complex systems. A comparison of various probing techniques will be presented, and recent results of laser spectroscopic investigations of plasma etching and CVD of silicon and III-V compounds will be reviewed.
Laser-Induced Fluorescence Diagnostics of CF4/O2/H2 Plasma Etching
Authors: Pang S. , Brueck S. R. J. 
Published: March 2011

ABSTRACTLaser-induced fluorescence experiments have been carried out during CF4/O2/H2 plasma etching of Si and SiO2. Measurements of relative CF2 radical concentrations as a function of rf power, frequency, pressure, and gas composition are reported. The results are correlated with etch rates of Si and SiO2. The balance between CF2 and F concentrations is shown to influence the etching process strongly.
Semiconductor Thin Films Grown by Laser Photolysis
Authors: Eden J.G. , Greene J.E. , Osmundsen J.F. , Lubben D. , Abele C.C. , Gorbatkin S. , Desai H.D. 
Published: March 2011

ABSTRACTThin (< 1.2 μpm) Ge and Si films have been grown with rates up to 3.6 μm/hr by laser-induced chemical vapor deposition (LCVD) on a variety of substrates. Germanium films grown on amorphous SiO2 (quartz) by photodissociating GeH4 in He at 248 nm (KrF laser) exhibit grain sizes of 0.3 – 0.5 μm that increase only slightly up to the pryolytic threshold for GeH4 (280°C). On (100) NaCl, however, Ge films grown at a substrate temperature of 120°C are expitaxial. The activation energy for the LCVD growth of Ge films (from GeH4) on SiO2 is measured to be 85 ± 20 meV which suggests that germanium is arriving at the substrate in atomic form. The wavelength and intensity dependence of the initial film growth rate supports the conclusion that this process is photolytic and is initiated by the absorption of a single photon.
Pulsed UV Excimer Laser Doping of Semiconductors
Authors: Deutsch T. F. 
Published: March 2011

ABSTRACTUV excimer lasers have been used to dope semiconductors by a one–step process in which the laser serves both to release dopant atoms from a parent molecule and to melt the surface, allowing incorporation of dopant atoms by liquid state diffusion. The technique has been used to dope Si, GaAs, and InP. Shallow junctions formed by the technique have been fabricated into efficient Si and GaAs solar cells.
Formation of CdO and Cu2O Films by Laser Irradiation of the Corresponding Metallic Films in Air
Authors: Andrew Rod , Baufay Luc , Pigeolet Andre , Wautelet Michel 
Published: March 2011

ABSTRACTWe describe the oxidation of 1000 Å thick metal films on glass substrates when exposed to a scanning laser beam. For Cd and Cu films optical spectroscopy shows an energy gap of 2.45 eV and 2 eV respectively, in agreement with published data for CdO and Cu2O. We measure the power threshold for complete oxidation in a single scan and deduce the maximum temperature, which is inconsistent with thermal oxidation data but corresponds to the m.p. of the metals. We point out the important contribution of the heat of formation to the temperature balance and demonstrate that in the case of Al this effect is sufficient to destroy any oxide formed.
Laser Fabrication of Microstructures: Effect of Geometrical Scaling on Chemical Reaction Rates
Authors: Ehrlich D. J. , Tsao J. Y. 
Published: March 2011

ABSTRACTLaser chemical processing for microfabrication makes use of chemical reactions and phase changes confined to micrometer-scale dimensions at vapor/solid and liquid/solid interfaces. When conditions are established for rapid interfacial reactions, processing speeds can become limited by diffusive transport. These diffusion-limited rates, however, increase by many orders of magnitude as the microreaction geometry is reduced to micrometer lengths using well-focused visible and UV beams. A calculation of the geometric scaling of such rates is summarized here. For realistic conditions, rate increases of up to four decades are predicted relative to corresponding reactions on semi-infinite plane surfaces.
UV Photodecomposition for Metal Deposition: Gas Vs. Surface Phase Processes
Authors: Wood Thomas H. , White J. C. , Thacker B. A. 
Published: March 2011

ABSTRACTPhotodecomposition of organometallic gases has been shown to be potentially useful for high resolution direct metal deposition. However, a number of problems, particularly the low writing rates, must first be solved. An understanding of the deposition mechanism is essential to this task. In particular, the decomposition must be shown to occur either in the gas phase or in the adsorbed layer. This question can be resolved by the dependence of the writing rate on spot size. Measurements of the process show that once the deposition begins the bulk of the deposit occurs from decomposition in the gas phase.