bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the Structure of Planar Defects in ALN
Authors: Mckernan Stuart , Carter C. Barry 
Published: March 2011

AbstractAluminum nitride has a great potential as a semiconductor substrate material. However, the defects which occur in this material are very detrimental to the material properties. ‘Domelike’ or ‘D’ defects, consisting of a flat basal fault joined to a curved planar fault, are examined by TEM. They are shown to be inversion domains, using a newly developed technique for polarity determination in the TEM. Structural models are proposed for the defects which incorporate a layer of alumina one unit cell thick into the basal fault of the defect.
Interfacial Failure In Ti/Sio2 and Ti/AIN System And Temperature Dependence Of Hardness Of AIN
Authors: Liu T. , Notis R. , Chou Y. T. 
Published: March 2011

AbstractThe load dependence of interracial failure induced by microindentation has been studied. It is demonstrated experimentally that substrate lateral defects induced by indentation contribute significantly to interracial failure. The microhardness of translucent AIN was measured at temperatures up to 1200°C. The hardness decreased from 10.6GPa at room temperature to 4.0GPa at 1200°C.
Electroless Plating of Copper Interconnections on Ion Beam Catalyzed Polyimide
Authors: Flottmann T. , Tulke A. , Esper E. , Lohmann W. 
Published: March 2011

AbstractDecomposition of a palladium compound by ion irradiation has been used to catalyze electroless plating on polyimide. First, palladium-acetylacetonate or -acetate is spin-coated on a polyimide substrate. The thin resist film is then irradiated through a mask with He or Ar ions of 100 keV energy. After washing off the film parts which were not exposed to the ion beam, copper is deposited on the catalyzed polyimide substrate in an alkaline electroless plating bath. When using alkaline resistant polyimide, copper lines several microns thick can be plated. The chemical surface composition of the Pd-compounds after ion beam exposure has been investigated with ESCA. It has been found that the Pd is partially reduced. Pd-acetate is more effective to form catalytic sites than Pd-acetylacetonate.
The interdiffusion of Cu, Co and Au Thin Films at elevated temperatures
Authors: Madakson Peter , Liu Joyce C. 
Published: March 2011

AbstractA detailed study of the interdiffusion and resistivity of Cu/Au, Cu/Co/ Co/Au and Cu/Co/Au thin film structures was carried out at temperatures ranging from 25 to 550°C1. Both Cu and Au, in the Cu/Au structure, intermix readily even at temperatures as low as 150°C and the interdiffusion is accompanied by rapid increase in resistivity. Very little interdiffusion occurs in the Cu/Co, Co/Au or Cu/Co/Au thin film structures up to about 400°C, after which the resistivity increases. The very rapid increase in resistivity observed at 250°C for the Cu/Au system and at 450°C for Cu/Co/Au, is associated with recrystallization of the films into large grains and the formation of AuCu, Cu3Au and Cu3Au2 compounds. The Cu/Co/Au structure recrystallizes at a higher temperature because of the time needed for Cu and Au to diffuse through the Co layer, which did not react significantly with either Au or Cu.
Oxidation Kinetics of (Pb-In) Single-Phase Alloys
Authors: Zhang M.-X. , Chang Y. A. , Marcotte V. C. 
Published: March 2011

AbstractThe solid state oxidation kinetics of Pb-In single-phase alloys were studied using AES (Auger Electron Spectroscopy) combined with sputter depth profiling. Samples containing 3, 30, 64 at% In were oxidized in air from room temperature up to 275 °C. At room temperature, the oxidation behavior for all three alloys was found to obey a direct logarithmic law. As the temperature is increased, the kinetics change from logarithmic to parabolic behavior. The transition between logarithmic and parabolic kinetics occurs between 150 °C and 175 °C for Pb-3 at% In alloy, and below 100 °C for Pb-30 at% In and Pb-64 at% In alloys. Using the solidius temperature as melting temperature of an alloy, the transition temperature for Pb-In alloys was observed to be approximately 70 – 75 % of the melting temperature.
Femtosecond Time Domain Techniques for Characterization of Linear and Nonlinear Optical Properties in GaAs Waveguides
Authors: Anderson K. K. , Lagasse M. J. , Haus H. A. , Fujimoto J. G. 
Published: March 2011

AbstractFemtosecond time domain measurements can provide a powerful approach for characterizing both the nonlinear as well as linear optical properties of waveguide devices. We describe a new time division interferometry technique to perform direct measurements of the nonresonant nonlinear index of refraction in AIGaAs waveguides. In addition, femtosecond time of flight measurements permit linear properties such as absorption and dispersion to be characterized using time domain techniques. These techniques permit a comprehensive characterization of linear and nonlinear waveguide properties.
Mechanistic Aspects of the Deposition of thin Alumina Films Deposited by Mocvd
Authors: Morssinkhof R. W. J. , Fransen T. , Heusinkveld M. M. D. , Gellings P. J. 
Published: March 2011

AbstractThe object of this study is the decomposition mechanism of Aluminium-Tri- Isopropoxide and its influence on the deposition of A12O3 by MOCVD. DSC experiments reveal that the decomposition occurs in two steps: formation of aluminum hydroxide, followed by dehydration.Deposition of A12O3 takes place by diffusion of AI(OH)3 to the substrate surface, followed by dehydration to Al2O3. This is supported by the insignificant amount of carbon found in the coating analyzed by XPS. A Langmuir type adsorption of the reactive components explains the change in reaction order of ATI from one at atmospheric pressure to two at 3 torr.
Selective Chemical Vapour Deposition of Tungsten Using SiH4/WF6 Chemistry
Authors: van der Jeugd C. A. , Verbruggen A. H. , Leusink G. J. , Janssen G. C. A. M. , Radelaar S. 
Published: March 2011

AbstractThe effect of deposition temperature and SiH4/WF6 flow ratio on the resistivity and impurity content of SiH4/WF6 tungsten films has been investigated. It is found that low deposition temperatures and high SiH4/WF6 ratios result in films with a high resistivity up to 150 μΩcm, whereas films deposited at high temperatures have a resistivity of 9 μΩcm. From Electron Probe Micro Analysis and Auger Electron Spectroscopy we conclude that the resistivity increase is due to silicon which is incorporated in the tungsten film during deposition. This results in a resistivity increase of 20 to 40 μΩcm per at% Si.
Identification of W20O58 Phase In CVD Tungsten Films
Authors: Lawrence M. , Dass A. , Sivaram Siva , Tracy Bryan 
Published: March 2011

AbstractThin films of tungsten grown in a CVD reactor by the reduction of hydrogen and silane consisted of a two phase microstructures; a matrix phase of bcc tungsten, and a second phase of W20O58. The second phase is uniformly distributed in the film and does not afeoct 5athe electrical resistivity of hydrogenreduced films (8 μohm-cm). However, dissolved oxygen in the silane-reduced film contributes to the observed higher electrical resistivity (13 μohm-cm) along with smaller grain size. The larger amount of oxide in the hydrogen-reduced film correlates with its slower growth rate when compared to the silane-reduced film which contained a smaller amount of oxide phase.
Investigation of CVD β-SiC Surfaces Produced VIA a “Novel” Surface Replication Process
Authors: Collins Aliki K. , Keeley Joseph T. , Pickering Michael A. , Taylor Raymond L. 
Published: March 2011

AbstractA novel replication process for silicon carbide surfaces has been developed. A polished polycrystalline chemical vapor deposited (CVD) β-SiC surface was reproduced from a SiC substrate (mandrel) by a two-step pretreatment process followed by CVD of SiC. In this paper we describe the process and present characterization data for both the substrate and the replicated surfaces. Based on the characterization results, we have developed a model which describes the chemical reactions that occur during the replication process.
Application Of Ai Control To The Vls Sic Whisker Process
Authors: Shalek Peter D. , Parkinson W. J. 
Published: March 2011

AbstractSilicon carbide whiskers have excellent mechanical and chemical properties, making them very desirable as a reinforcement for structural ceramic and other composite materials. Los Alamos has developed a laboratoryscale batch process for producing very high quality SiC whiskers by the vapor-liquid-solid (VLS) method which is an active candidate for technology transfer involving significant scale-up. The process, however, involves quite complex chemical/physical and parametric relationships and has not as yet lent itself successfully to modeling. An expert computer system was therefore developed to facilitate the transfer of this technology to industry. Optimum conditions were determined by relating the many process parameters to product results to establish a set of rules for running the process. These are incorporated in a two-phase expert system designed to guide inexperienced users. In Phase I, an expert consultant program provides the user with information that enables him to set up the run. This information is incorporated into the rule base that makes up Phase II- the control system. At present, the operator functions as the controller by responding to the decisions of the expert system; automation can be added later.
Laser Chemical Vapor Deposition Of Tin Films
Authors: Chen B. , Biunno N. , Singh R. K. , Narayan J. 
Published: March 2011

AbstractWe have investigated the pyrolytic deposition of TiN thin films on molybdenum and 304 stainless steel substrates by continuous wave (CW) and pulsed CO2 (λ=10.6 μm) laser radiation. A flow rate of NH3: TiCl4 of 5:1 was maintained during the deposition process. The substrate temperature was controlled by varying the intensity of the incident laser irradiation. The TiN films were characterized by Transmission Electron Microscopy (TEM), Auger Electron Spectroscopy (AES) and Rutherford Backscattering Spectrometry (RBS). TEM results showed that the films were polycrystalline of equiaxed nature with diffraction patterns containing the characteristic TiN rings. The films had a lattice parameter of 4.24Å. AES results showed a slight incorporation of oxygen.
A Low Temperature CVD Process for TiN Coatings
Authors: Aguero A. , Little D. , Lowden P. 
Published: March 2011

AbstractA novel low temperature process for the chemical vapour deposition of titanium nitride films has been developed. Titanium sub-halides generated “in situ” by chlorination of titanium pellets are subsequently reacted with ammonia at reduced pressure and temperatures of 450–600° C. The coatings have excellent adhesion and wear resistance. A description of the process and the properties of the coatings produced by it will be presented.
Low Temperature MoCVD Routes to Thin Films from Transition Metal Precursors
Authors: Girolami Gregory S. , Gozum John E. 
Published: March 2011

AbstractA review is presented of early and recent advances in the metal-organic chemical vapor deposition (MOCVD) of thin films from organotransition metal and related precursors. Routes to pure metals and alloys, metal carbides, metal borides, metal nitrides, metal silicides, and related materials will be summarized. Also included is a discussion of both the advantages and disadvantages of employing metal-organic precursors that contain transition elements.
Characterization of Mocvd Grown Epitaxial Ceramic Oxide Thin Films
Authors: Parker J. C. , Chang H. L. M. , Xu J. J. , Lam D. J. 
Published: March 2011

AbstractCharacterization of TiO2 films grown by the MOCVD technique was carried out using micro-Raman scattering. The effects of processing parameters on the film composition and morphology were investigated. The micro-Raman technique was shown to be a useful tool for characterizing oxide thin films grown by the MOCVD technique.
Anisotropy in the Far Infrared Conductivity of Magnetically-Oriented YBa2Cu3O7-δ Between 50–300K
Authors: Lu F. , Perry C.H. , Chen K. , Markiewicz R.S. 
Published: March 2011

AbstractThe far infrared reflectance of magnetically-oriented YBa2Cu3O7-δ has been measured from 30–600 cm-1 over the temperature range 300–50 K. A strongly temperature dependent optical anisotropy is observed in this region. The low energy Ē⊥c spectrum displays a high reflectivity associated with the dominant free carrier contribution. Peaks corresponding to phonons are present in the spectrum associated with the direction perpendicular to the high conductivity Cu - O planes. However the reflectivity for Ē∥c is not characteristic of an insulating material but rather shows a metallic-like rise with decreasing photon energy. The plasma frequencies for both polarizations, obtained from fits to the reflectance data, decrease with decreasing temperature. There is some evidence in the parallel conductivity data taken below Tc, for the onset of an energy gap that is substantially smaller than that deduced for the in-plane value; such a result suggests a large gap anisotropy. The parameters describing a number of low frequency phonon modes for Ē∥c have been determined from fits to the R∥ data. Most show a slight softening as Tc is traversed.
Physical Properties of Bi2sr2cuo6, the Semiconducting Phase, Structurally Distinct from the N=L Bi‐Cuprate Superconductor
Authors: Chakoumakos B. C. , Sonder Edward , Sales B. C. 
Published: March 2011

AbstractThe stable phase that forms near 2:2:1 in the Bi‐Sr‐Cu oxide system is now recognized as a semiconducting phase structurally distinct from the n = 1 Bi‐cuprate superconductor, whose actual composition (Bi2Sr2‐xCuO6‐y, x= 0.1‐0.25, y=0‐0.5) is deficient in Sr. The 2:2:1 phase forms by a slow solid‐state replacement of the superconducting phase for compositions near 2:2:1. It also can be grown from melt compositions involving several phase assemblages, but single‐phase products are not obtained, implying incongruent melting. Alumina and zirconia crucibles promote the growth of the superconducting phase by reacting with the melt to remove Sr, whereas Au crucibles promote the growth of the 2:2:1 phase. Owing to its fine‐grained, fibrous habit, structural characterization has been difficult. Of the unit cells proposed, the C‐centered monoclinic cell of Roth et al. provides the best fit to our x‐ray powder and single‐crystal precession data, a = 24.522(9), b = 5.426(2), c = 21.983(9) Å, β = 105.00(3)°. Perfect prismatic cleavages intersecting at ‐148° and ‐32° are indexed as {100} and {‐201} forms. Although, the superconducting n = 1 Bi‐cuprate exhibits variable Sr and O contents, the 2:2:1 phase appears to be a single composition with no oxygen exchange observed by TGA, although it may be somewhat deficient in Cu. The 2:2:1 phase is semiconducting as determined by electrical resistivity measurements, with an apparent activation energy of 0.013 eV. For a 2:2:1 stoichiometry, the measured density of ‐7.2. g/cm3 implies 16 formula units per cell.
Variation in Tc and Carrier Concentration Caused by Change of Oxygen Content in Tl-Based Superconductors
Authors: Shimakawa Y. , Kubo Y. , Manako T. , Igarashi H. 
Published: March 2011

AbstractTc variations observed in some Tl-based superconductors were studied. Clear correlations were found between Tc, carrier concentration, and c-axis length. In particular, for Tl2Ba2CuO6, a decrease in oxygen content of about 0.1 per formula unit, which corresponded to a decrease in hole concentration of about 0.2, increased Tc up to about 80K from a metallic non-superconductor, and elongated the c axis by about 0.4%. In addition, as Tc values increased systematic changes in metal-sheet separations were observed. Tc variations caused by a change in oxygen content were also observed in Tl2Ba2CaCu2O8 and Tl2Ba2Ca2Cu3O10. It was demonstrated that superconductivity appears in a certain appropriate range of carrier concentration similar to those observed in other high-Tc superconductors.
Ion-Irradiation Effects in Tl2Ca2Ba2Cu3010 Superconductors
Authors: Barbour J. C. , Kwak J. F. , Venturini E. L. , Ginley D. S. , Peercy P. S. 
Published: March 2011

AbstractThe effects of oxygen and helium ion irradiation on the superconducting properties of Tl2Ca2Ba2Cu3010 thin films were investigated. The transition temperature and width were monitored as a function of ion fluence using both magnetization and resistivity measurements. These data suggest that superconductivity is completely suppressed at 0.020 dpa for both He and 0 ion irradiation. Further, the rate of decrease in Tc as a function of deposited energy showed that the dominant mechanism causing damage-induced suppression of Tc in these films was from atomic collisions.
Magnetization Measurements of 5µm Ba0.6K0.4BiO3 Crystals: Approach to Intrinsic Behavior with Decreasing Size
Authors: Grader G. S. , Hebard A.F. , Schneemeyer L. F. 
Published: March 2011

AbstractMagnetization measurements on cubic Ba0.6K0.4BiO3 crystals, approximately 5µm in radius, have been obtained using a recently-developed electrodynamic force balance technique. The onset of flux entry in an external filed H is marked by a pronounced deviation from a linear magnetization at a critical field H*c1 together with a noticeable reorientation of the crystal near H = 0, a reorientation caused by a field-induced torque on the remanent moment. The dependence of H*c1 on temperature is linear over the temperature range 7K≤T≤30K with a slope approximately a factor of three higher than published values. These higher values of H*c1 imply either intrinsically cleaner material with a reduced Ginzburg-Landau parameter K or higher surface critical fields. These results suggest that the intrinsic properties of high-Tc superconductors may be more accurately reflected in small crystals which are more likely to be of higher quality than larger crystals.
Anisotropic Thermal Conductivity of Superconducting Lanthanum Cuprate
Authors: Morelli D.T. , Doll G.L. , Heremans J.P. , Jenssen H.P. , Cassanho A. , Dresselhaus M.S. 
Published: March 2011

AbstractThe thermal conductivities of superconducting, Sr-doped lanthanum copper oxide single crystals have been measured from room temperature to below 100 mK parallel and perpendicular to the copper oxide planes. While the results indicate that the heat conduction is strongly anisotropic, the data have been analyzed in terms of a modified Bardeen-Rickhayzen-Tewordt theory of lattice thermal conductivity. It is shown that while electron scattering plays an important role in limiting the in-plane heat conductivity, this scattering channel is masked by other mechanisms for heat transport across the planes.
The Sputter Deposition and Characterisation of Epitaxial Magnesium Oxide Thin Films and Them Use as a Sappihre/YBCO Buffer Layer
Authors: Morris G W , Somekh R E , Barber Z H , Williams E J , Schmahl W W , Evetts J E 
Published: March 2011

AbstractIf useful electronic devices are to be fabricated from thin films of the high critical temperature oxide superconductors, such as yttrium barium copper oxide (YBCO), then films must be formed on substrates with dielectric properties which permit device operation at high frequencies, such as sapphire. It is, however, difficult to form high quality YBCO on sapphire because of reaction with the substrate and because epitaxy is not readily achieved.We report the deposition of epitaxial thin films of magnesium oxide, by UHV reactive d.c. magnetron sputtering, on variously orientated substrates of sapphire, and the characterisation of the MgO/sapphire system by x-ray and TEM techniques.Onto such films of MgO on sapphire we have deposited films of YBCO which were strongly textured with the c-axis perpendicular to the plane of the substrate and which were superconducting without the need for a high temperature post deposition anneal.
Effects of Low Magnetic Fields on Gold-YBCO Contacts
Authors: Tzeng Yonhua , Belser Mitchell A. 
Published: March 2011

AbstractThe effects of low magnetic field (0–40 Gauss) on electrical properties of gold-YBCO contacts are investigated. The contact resistance increases significantly with applied magnetic fields. For high magnetic field or when high current is flowing through the contact, the contact resistance decays after removing the magnetic field to a finite value greater than that is measured before the contact is exposed to the magnetic field and stays there for long time as long as the sample is kept below the superconductivity critical temperature.
Influence of the Partial Substitution of Small Rare Earths for Ca in the Superconductive Bi-Sr-Ca-Cu-O Compound
Authors: Casanove M. J. , Baules P. , Snoeck E. , Roucau C. , Millet P. , Enjalbert R. , Galy J. 
Published: March 2011

AbstractSuperconductive 2:2:1:2 phases of the type Bi2Sr2Ca1-yLnyCu2O8+x+y/2, where Ln stands for Yb or Er, have been synthesized and characterised by X-ray and electron diffraction. The small rare earth atoms prove to substitute preferentially in the Ca site. The electrical properties as well as the structural characteristics of these compounds are affected by the rare earth substitution rate. It is shown, in particular, that the long axis parameter of the subcell and the incommensurate period of the modulation decrease with increasing y. The substitution of trivalent cations for Ca requires the presence of additional oxygen atoms in the structure, the location of which is discussed.
Development of a Composite Tape Conductor of Y-Ba-Cu-O
Authors: Blaugher R.D. , Hazelton D.W. , Rice J.A. , Walker M.S. 
Published: March 2011

AbstractSamples of a prototype composite tape conductor have been prepared consisting of a thick layer of Y Ba2 Cu3 O7 (123) on a metallic substrate. A thick coating of 123 precursor powder was applied to the substrate by a mechanical compaction process. A melt-quench-growth technique was then employed to effect a textured grain development and improved current density. The resulting melt processed structure showed a textured 123 orthorhombic matrix with a dispersion of the 211 phase. The orthorhombic 123 phase was highly developed with an onset temperature of 90K and current density near 104 A/cm2 at 4T and 50K measured by a steady-state magnetization method.
Influence of Silver Infiltration on the Microstructure and Transport Properties of YbacuO
Authors: Ryelandt L. , Cassart M. , Vandenbosch A. , Delannay F. , Issi J-P. 
Published: March 2011

AbstractThe results of measurements of the transport properties of high‐Tc superconductors containing different amounts of silver are reported. The Tc and Jc values were found to be similar to that of the single phase YBaCuO compound whereas the electrical and thermal conductivities above Tc were drastically increased. A very low contact resistance was observed.
Texture Formation and Improvement of Grain Boundary Weak‐Links in Tape Shaped Wire Prepared by the Unidirectional Solidification Technique.
Authors: Okada Michiya , Yuasa Toyotaka , Matsumoto Tosimi , Aihara Katuzo , Seido Masahiro , Matsuda. Sinpei 
Published: March 2011

AbstractAu‐Sheathed Y‐Ba‐Cu‐O(YBCO) and Tl‐Ba/Sr‐Ca‐Cu‐O(TBSCCO) tapes were fabricated by the drawing‐rolling and subsequent unidirectional solidification. A typical microstructure of melt‐textured polycrystallite including fine particles of second phase(e.q. Y‐211) was observed. The Tl‐2223 tapes prepared at an optimized condition yielded Jc=15,300 A/cm2 at 77K in the absence of magnetic field, and l,100A/cm2 in a magnetic field of IT. The enhancement of Jc in a magnetic field is suggested to be due to the improvement of weak‐links in grain boundaries.