bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relations Between Structure and Tc In 123,124 and Thallium Oxide Superconductors
Authors: Hewat A.W. , Hewat E.A. , Bordet P. , Capponi J.J. , Chaillout C. , Chene-vas J. , Hodeau J-L. , Marezio M. 
Published: March 2011

ABSTRACTSmall structural changes accompany important changes in Tc in some materials. In YBa2Cu3O6+x, Cava et al. have shown that oxidation to YBa2Cu3O7 involves a significant shift of the oxygen bridging CuO-chains and CuO-planes toward the latter. In YBa2Cu4O8, Kaldis et al. have shown that a similar effect is produced with pressure alone. In both cases, Tc increases strongly. In TI2Ba2Cu1O6, Tc varies greatly depending on the precise method of preparation, though the stoechiometry appears unchanged. In this case, Tc may depend on subtle differences in oxygen content, and perhaps Cu-O bond lengths. These effects can be discussed in terms of charge transfer between intercalated layers of CuO-chains or TIO-planes, and conducting CuO-planes.
Preparation and Characterization of Several Conducting Transition Metal Oxides
Authors: Wold Aaron , Dwight Kirby 
Published: March 2011

ABSTRACTThe structure-property relationships of several conducting transition metal oxides, as well as their preparative methods, are presented in this paper. The importance of preparing homogeneous phases with precisely known stoichiometry is emphasized. A comparison is also made of the various techniques used to prepare both polycrystalline and single crystal samples. For transition metal oxides, the metallic properties are discussed either in terms of metal-metal distances which are short enough to result in metallic behavior, or in terms of the formation of a П*conduction band resulting from covalent metal-oxygen interactions. Metallic behavior is observed when the conduction bands are populated with either electrons or holes. The concentration of these carriers can be affected by either cation or anion substitutions. The discussion in this presentation will be limited to the elements Re, Ti, V, Cr, Mo, and Cu.
Short-Range Ordering by Displacement of Tl and O Atoms in Tl2CaBa2cu2O8 Studied by Pair Distribution Function and Rietveld Analysis
Authors: Toby B. H. , Dmowskia W. , Egami T. , Jorgensen J. D. , Subramanian M. A. , Gopalakrishnan J. , Sleight A. W. 
Published: March 2011

ABSTRACTAtomic pair distribution function analysis has demonstrated displacements of Tl and O atoms within the Tl-O layers with shortrange ordering of lower symmetry than the crystallographic lattice. Two models have been proposed for these displacements. Rietveld analysis neither confirms nor contradicts these models. Temperature-dependent PDF measurements show changes in local structure correlating with temperature.
Hole Conductors and Superconductors
Authors: Hirsch J.E. 
Published: March 2011

ABSTRACTA fundamental asymmetry exists between electrons and holes in solids. Electrons at the Fermi surface give rise to high conductivity and normal metallic behavior, holes at the Fermi surface yield poor conductivity and give rise to superconductivity. We review here the theoretical basis for this assertion and its implications, particularly for the understanding of high temperature superconductivity in oxides.
Evidence for Phonon-Mediated Coupling in Superconducting Ba0.6K0.4BiO3
Authors: Hinks D. G. , Dabrowski B. , Richards D. R. , Jorgensen J. D. , Pei Shiyou , Zasadzinski J. F. 
Published: March 2011

ABSTRACTSuperconducting Ba0.6K0.4BiO3, with a Tc of 30K, shows a large 18O isotope effect which indicates that phonons are involved in the pairing mechanism. Infrared reflectivity measurements indicate a value for the superconducting gap consistent with moderate coupling (2Δ/kTc = 3.5 ± 0.5). A mediating energy for pairing of about 40 meV would be required to obtain a Tc of 30K. Strong coupling of electrons by optical phonons (which are present in this material with energies up to 80 meV) could account for the observed transition temperature. Recent tunneling spectroscopy shows the presence of strongly coupled optical phonons in the 40 to 70 meV region, indicating that superconductivity in this material may be phonon mediated.
Ordered Oxygen Arrangements in Y1Ba2Cu3O7−x
Authors: Beyers R. , Ahn B.T. , Gorman G. , Lee V.Y. , Parkin S.S.P. , Ramirez M.L. , Roche K.P. , Vazquez J.E. , Gür T.M. , Huggins R.A. 
Published: March 2011

ABSTRACTWe describe the ordered oxygen arrangements in Y1Ba2Cu3O7−x samples prepared in precisely controlled oxygen environments using a solid-state ionic tehnique. The so-called “Ortho II”phase, characterized by a 〈1/200〉 superlattice wave vector, exists at oxygen contents from 6.28 to 6.65, with electrical properties that range from insulating to superconducting at up to 60 K. Additional ordered structures occur at oxygen contents from 6.65 to 6.90. All of the ordered structures are consistent with the removal of entire chains of oxygen along the b axis, which minimizes the number of three-fold coordinated copper and creates Cu+1 ions even in oxygen-rich samples. We found no evidence for phase separation between 6.0 and 7.0 or between 6.5 and 7.0. Phase separation, if it occurs at all, occurs on the 60 K and 90 K plateaus.
Ion-Beam Induced Epitaxial Crystallization of GexSi1–x/Si Heterostructures
Authors: Elliman R.G. , Ridgway M.C. , Williams. J.S. 
Published: March 2011

ABSTRACTAmorphous GexSi1–x layers are shown to crystallize epitaxially from an underlying (100) oriented Si substrate when irradiated with 1.5 MeV Ne ions at temperatures as a low as 275°C. For a given Ne fluence, the extent of crystallization is shown to increase with increasing Ge content, consistent with the increased defect production rate in these alloys. It has also been demonstrated that strained layer configurations can be grown by ion-beam annealing and that such layers exhibit a commensurate to incommensurate transformation within the same composition range as layers grown by molecular beam epitaxy.
Amorphous to Polycrystal Transition Assisted by Ion Beam Irradiation in Silicon
Authors: Spinella C. , Lombardo S. , Campisano S. U. 
Published: March 2011

ABSTRACTThe ion beam induced growth of isolated silicon grains has been studied in chemical vapor deposited amorphous layers. The crystal radius increases linearly with the 1on dose and the growth rate depends in a complex way on the irradiation temperature in the 320 - 480 °C investigated temperature range. The grain density does not depend on the ion dose but it increases exponentially with increasing irradiation temperature. The grain density obtained after a pure thermal process on similar samples is In any case larger than the density appearing after ion irradiation. These facts may be explained by assuming that during ion irradiation only pre-existing seeds whose size is larger than a critical value can grow. This critical cluster size is larger than the critical cluster size for a pure thermal process.
Effect of Oxygen Implantation Conditions on Buried Si02 Layer Formation using a Multiple Step Process
Authors: Namavar F. , Cortesi E. , Pinizzotto R.F. , Yang H. 
Published: March 2011

ABSTRACTWe have studied the effect of implantation temperature, dose step, and total dose on the buried Si02 layer formed with a multiple low dose oxygen implantation process. Furthermore, we have produced a continuous, high quality buried SiO2 layer about 1500 Å thick with a dose of only 7 × 1017 0+/cm2 at 160 keV. The thin SiO2 layer is important not only because of the possible economic advantages of reduced dose, but also because a thinner oxide layer is more radiation hard.
Silicon Oxide Film Formation by the Simultaneous use of a Microwave Ion Source and an Icb System
Authors: Takaoka Gikan H. , Tsuji Hiroshi , Ishikawa Junzo 
Published: March 2011

ABSTRACTSiO2 films were prepared at a substrate temperature of 100°C by the simultaneous use of a microwave ion source and an ICB system. Transparent and good insulating SiO2 films could be obtained by using 02 gas ions, and they were thermally and chemically stable. Furthermore, both the ionization energy and the incident energy of the 02 gas ions were found to enhance the chemical reaction between SiO and 02 molecules, resulting in the Si02 film formation at a low substrate temperature.
Zirconium Nitride Films formed by Dynamic Ion Implantation
Authors: Oppenheim I. C. , Padmanabhan K.R. 
Published: March 2011

ABSTRACTRF sputter deposition of 500 nm thick zirconium films was carried on simultaneously with implantation of singly ionized molecular nitrogen. Samples were prepared at room temperature (23°C) with a nitrogen to zirconium arrival ratio varying from 2.7x10-2 to 4.4x10-1 and with the ion energy varying from 100 to 300 keV.Stoichiometry of the films and ion concentration profiles were determined by Rutherford Backscattering Spectrometry. Results from a theoretical model for the ion concentration profiles were compared to profiles derived from experiments. Grazing Angle X-Ray Diffraction was used to correlate nitride phase formation to processing parameters.Knoop microhardnesses of films deposited on 304 stainless steel substrates were determined. The relative microhardness of the samples were studied as a function of parameters such as film stoichiometry and ion implantation energy.
Observation of Pulsed Laser – Induced Melting of Solid Surfaces by Optical Spin Orientation
Authors: Vaterlaus A. , Lutz M. , Guarisco D. , Aeschlimann M. , Stampanoni M. , Meier F. 
Published: March 2011

ABSTRACTThe optically induced spin polarization P of the photoelectrons emitted from tin and germanium during ps and ns laser pulses is measured as a function of the pulse energy. P is defined by the lattice symmetry of the sample. It vanishes for amorphous or molten surfaces. The melting of the metal and the semiconductor is found to occur on a time scale which is short compared to the duration of a 70 ps laser pulse. The emission of positive ions starts at the laser intensity for which the drop of the polarization is observed. If Ge is heated with ns laser pulses a temperature dependent shift of the work function causes a decrease of the spin polarization for laser energies far below the energy necessary for melting. With ps laser pulses the polarization only vanishes for pulse energies exceeding Eion- The difference between the ps and ns measurements on Ge points to an unexpected dynamical behavior of the work function shift in semiconductors.
TemperatÜRe Measurement by Infrared Transmission for Rapid Thermal Processing Applications
Authors: Sturm J.C. , Schwartz P.V. , Garone P.M. 
Published: March 2011

ABSTRACTWe report a new non-invasive optical technique for the measurement of the absolute temperature of silicon wafers in a rapid thermal processing environment. The method is based on the temperature dependence of the infrared absorption of silicon. Unlike pyrometry, the method can be used with a quartz processing chamber, and it is well-suited to the temperature range of 400 °C to 800 °C. Temperature resolution on the order of one degree can be achieved, and the method can easily be applied to homoepitaxial and certain heteroepitaxial growth cycles.
The Effects of Annealing on the Structure and Distribution of Charge States of Iron Implanted into A-Al2O, at 77 K
Authors: Mchargue C. J. , Sklad P. S. , Mccallum J. C. , White C. W. , Mccallum J. C. , White C.W. , Perez A. , Marest G. 
Published: March 2011

ABSTRACTImplantation of iron Into α-Al2O3 at 77 K produces an amorphous state for fluences greater than about 3 × 1016 Fe/cm2. Iron in the as-implanted (amorphous) specimens is distributed among two Fe2+, two Fe4+, and the Fe° states. The conversion electron Mössbauer (CEMS) spectra for a sample containing 7 × 1016 Fe/cm2 show all iron to be converted to Fe3+ after annealing in oxygen for 1 h at 700°C and above. The transmission electron microscopy (TEM) shows the structure to be mostly Y-A120, after the 900°C anneal and all α-Al2O, after the 1100°C anneal.
Investigation on mechanisms for ion Beam Induced Degradation of Polyimide
Authors: Xu X.L. , Zuyao Zhou , Lizhi Chen , Shichang Zou 
Published: March 2011

ABSTRACTThree types of ions with different atomic masses (B , Ar and As ) were chosen to irradiate polyimide films in similar conditions in order to check mechanisms of the formation of ion beam induced damage in polyimide. A four-point probe technique was used to measure sheet resistivities of implanted films. An ion mass effect on conductivity of ion irradiated polyimide film was discovered. The ion mass effect on ion beam induced change of conductivity and on the energy loss process of the ions in polyimide suggest that the electronic energy loss of incident ions is an important factor for the increase of conductivity of implanted polyimide, and the contributions of recoil ionization are restricted by the grave damages as a result of nuclear energy loss process of ions in targets. Our hypothesis is supported by automatic spreading resistance measurement of B implanted polyimide film coated on silicon substrate. The results of this work have been compared with the hypothesis of degradation through direct knock on of atoms in polyimide, proposed by D.Fink et al [Nucl. Instr. and Meths B32 (1988) 125]
Thermal Annealing Investigation of the Optical Properties of BxN1-X Films Fabricated by Ion Beam Assisted Deposition and Application for an Optical Filter
Authors: Carosella C.A. , Donovan E.P. , Hubler G.K. , Skowronek A.E. 
Published: March 2011

ABSTRACTThe annealing behavior of the optical properties of boron nitride films (BxN1-x) is described for films fabricated by ion beam assisted deposition. The data are needed for the precise manufacture of optical filters, where the index of refraction must be predicted from deposition parameters and film annealing history.The reflection of homogeneous samples deposited at room temperature on (100) silicon substrates was measured from 400 to 3125 nm. to obtain the wavelength dependence of the index of refraction as a function of film nitrogen content. Nitrogen atom fraction was varied from 0.325 to 0.5 by variation of the incident of nitrogen ion beam current to evaporant boron flux ratio. The films were annealed in argon at 500 C and 700 C, and the optical measurements repeated after each anneal. The index of refraction obtained for the annealed films was used to design a narrow band optical reflection filter at 1060 nm. The filter, constructed by sinusoidally varying the index of refraction of the BxN1-x film by varying ‘x’, performed as designed.
Effect of γ-Radiation on Physico-Chemical Properties of Lanthanum Cobaltate (LaCoO3)
Authors: Srinivas B. , Rao V.R.S. , Kuriacose J.C. 
Published: March 2011

ABSTRACTThe influence of γ-radiation on LaCoO3, for the catalytic decomposition of H2O2 has been studied. ESR and XPS studies of γ-irradiated LaCoO3, snowed, the formation of chemisorbed oxygen (O2) and reduction of Co2+ to Co . γ-irradia]:ion of LaCoO3. causes a decrease in electrical conductivity due to the trapping of charge carriers by the chemisorbed oxygen. SEM photographs of the Y-irradiated sample pellets reveal surface cracks and surface corrosion due to the diffusion of transition metal to surface. The enhancement in the catalytic activity for the decomposition of H2O2 is found to be directly proportional to the reduced metal content.
Effects of Ion Beam Bombardment on the Crystalline Structure of Polymers: The Case of Pet+
Authors: Prppleo R.M. , Rrrujo M.R. , Livi R.P. 
Published: March 2011

ABSTRACTWe discuss the amorphization process of semicrystalline and oriented PET (Polytethyleneterephtal ate)) thin toils by ion beam irradiation. P decrease in the bombarded samples melting point and enthalpy of fusion in the bombarded samples, as analysed by Differential Scanning Calorimetry (DSC), is associated with changes in the crystalline morphology and with an increase in the polymer disordered regions. Those facts are confirmed atso by a large decrease in the main X-ray diffraction peak amplitude as the tluence increases. P model of ion induced amorphization originally constructed for metals and semiconductors 11,23 was applied and cross-sections tor the process were obtained. The experimental data are well fitted using this model based on amorphization through the overlap of damage clusters, but an exclusive elastic collisions mechanism for the damage production cannot be inferred. As expected the electronic stopping mechanism also plays an important role in the polymer amorphization process.
Amorphous to Crystalline Phase Transformations in High Dose Ion Implanted Silicon
Authors: Williams J.S. , Thornton R.P. , Elliman R.G. , Li Y.H. , Pogany A.P. 
Published: March 2011

ABSTRACTCrystallization processes during thermal annealing have been studied for a number of group III, IV and V impurities implanted into amorphous Si. At high impurity concentrations, an amorphous to polycrystalline transformation is observed. For low solubility, low melting point species, this transformation is melt-mediated, whereas it can occur in the solid phase for other species such as Sb.
Stress and Plastic Flow in Silicon During Amorphization by Ion-Bombardment
Authors: Volkert Cynthia A. 
Published: March 2011

ABSTRACTThe in-plane stress in silicon wafers during amorphization by ion-bombardment was determined from wafer curvature measurements using an in-situ laser scanning technique. Measurements were made during room temperature bombardment with 2 MeV Ne, Si, Ar, Kr, and Xe ions. In all experiments, compressive stress was built-up in the bombarded region as a function of the fluence, until a maximum was reached at the dose required to form amorphous silicon. During further amorphization by bombardment, the stress decreased and eventually stabilized. If ion bombardment was interrupted during amorphization, a stress increase was observed over a period of several minutes; when the beam was turned on again, the stress returned immediately to the value measured before interruption. Step height measurements were performed on implanted wafers to determine the out-of-plane strain, and RBS was used to determine the damage profiles. A model is proposed that describes the behavior in terms of the expansion of crystalline silicon by the creation of defects and the flow of amorphous silicon under the ion beam.
Gettering of Cu at Buried Damage Layers Made by Si Self Implantation
Authors: Liefting J.R. , Schreutelkamp R.J. , Lu W.X. , Saris F.W. 
Published: March 2011

ABSTRACTChanneled implants have been performed with lOOkeV 28Si+ into p-type Si(100) to obtain a buried amorphous layer. Before and after recrystallization of the a-Si layer, Cu was implanted at an energy of 15 keV and a dose ranging from 5E13 to 1E15 I cm2- to obtain a high concentration of Cu in the near surface region. Also, Cu implants were performed into virgin Si for comparison. After Cu implantation, thermal annealing was performed at temperatures between 490 °C and 900 °C for 10 min. to 320 min. Cu profiles before and after annealing were studied with Rutherford Backscattering Spectrometry and channeling analysis. For the case where Cu was implanted after recrystallization of the buried amorphous layer, Cu was gettered at the position where the ale interfaces met during recrystallization. For the case where Cu was implanted before recrystallization, Cu diffused towards the buried a-Si region upon annealing and was trapped inside the recrystallizing buried amorphous layer. The results show that buried damage layers can effectively getter Cufrom the Si surface layer and gettering is most efficient at 600 °C.
Kinetics and Microstructure of Transiently Annealed Implanted Polycrystalline Silicon Layers
Authors: England J.M.C. , Timans P.J. , Mcmahon R.A. , Ahmed H. , Hill C. , Augustus P.D. , Boys D.R. 
Published: March 2011

ABSTRACTMicrostructural changes occurring during the early stages of rapid thermal annealing of polycrystalline silicon bipolar emitters crucially affect the final dopant distribution and hence the performance of these devices. The first stage of annealing is epitaxial regrowth in the solid phase of the layer amorphised by the implantation. In-situ studies using time-resolved reflectivity measurements, combined with cross-sectional transmission electron microscopy of partly annealed structures, have determined the effects of initial grain size, annealing temperature and amorphising species (Si or As) on the rate of regrowth and the microstructural changes which occur during annealing. As the grain size is reduced, the regrowth rate decreases and the interface roughness increases. Arsenic implantation alters the rate of regrowth in such a manner as to produce a smoother interface than that in silicon implanted material.
Effects of Ion Dose on the Morphology and Crystallization of Amorphous Germanium
Authors: Wang L.M. , Birtcherand R.C. , Rehn L.E. 
Published: March 2011

ABSTRACT1.5 MeV Kr+ irradiation of polycrystalline Ge at room temperature, and subsequent annealing were carried out with in situ TEM observations. After a Kr+ dose of 1.2x1014 ions/cm2, Ge in the electron transparent region was completely amorphized. Continuous irradiation of the amorphized Ge resulted in a high density of small cavities. These cavities, first observed after 7x1014 ions/cm2 with an average diameter of ∼3 nm, grew into large (∼50 nm) irregular-shaped holes, transforming the irradiated Ge into a sponge-like material after 8.5x1015 ions/cm2. The crystallization temperature and the morphology of the crystallized Ge after annealing were found to be dependent on the Kr+ dose. The sponge-like structure was retained after crystallization at ∼600°C.
X-Ray and Raman Topographic Studies of Gaas Implanted With 28Si+ and Pulsed Laser Annealed
Authors: Bowman R.C. , Knudsen J.F. , Adams P.M. , Yao H.D. , Compaan A.D. 
Published: March 2011

ABSTRACTDouble-crystal x-ray diffraction and topography, along with Raman spectroscopy and topography are used to study lattice reconstruction and carrier activation for pulsed laser annealed Si implanted GaAs. Although lattice strain is essentially eliminated, along with the production of carrier concentrations to about 3×1019 cm.3 at the center of laser annealed spots, incomplete removal of implant induced disorder and little dopant activation are observed in surrounding areas. Correlations of Raman and x-ray topographs suggest that concentric regions of partial melting, but without epitaxial regrowth, occur in the periphery of the laser annealed spots.
Effects of Nitrogen Ion Implantation in 304 Stainless Steel at High Temperatures
Authors: Shrivastava Sadhna , Tarey Ram D. , Bhatnager M.C. , Jain Amttaeh , Chopra K.L. 
Published: March 2011

ABSTRACTWe studied the effect of varying the target temperature (by changing the beam power) on the structure and properties of nitrogen ion implanted 304 stainless steel. With a beam power of 0.1 W/ cm2 the target temperature is restricted to 150°C. After a dose of 3. 5x1017N2+/cm2 the microhardness measured at 10g increases by 15%. With a beam power of 1.1 W/cm2 the target temperature is 500°C. After the same dose as before, the irdcrohardness increase is 40%. Glancing Angle X-ray Diffraction and Auger depth profiling results suggest that the increased hardness is due to the presence of nitrogen in solution as opposed to complete precipitation. A sample deformed by compression formed an enhanced oxide layer during implantation. This oxide layer appears to have a capping action against the out-diffusion of nitrogen.
Selective Area Deposition of Conducting Palladium Films on Polyimide Resins
Authors: Kim Yoon-Gi , Bialy S. , Miller R.W. , Spencer J.T. , Dowben P.A. , Datta Saswati 
Published: March 2011

ABSTRACTWe have demonstrated that the selective area deposition of palladium on polyimide substrates is possible through the U.V. photolysis of (π-allyl)(π-cyclopentadienyl) palladium. This photolytic deposition process did not result in any apparent damage to either the Ultem 1000 (polyetherimide) or Kapton substrates (polyimide substrates). The resistivity of the palladium films (< 0.lum) suggests that the films are porous.