bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative Studies of Tetrahedral Bonding in Amorphous Carbon Films Using Ultraviolet Raman Spectroscopy
Authors: Gilkes K. W. R. , Prawer S. , Robertson J. , Sands H. S. 
Published: April 2011

ABSTRACTThe bonding in a series of unhydrogenated amorphous carbon films has been analysed quantitatively using Raman spectroscopy with ultraviolet excitation. The Raman spectra exhibit two broad Raman peaks at 1650 cm−1 and 1100 cm−1, due to sp2 and sp3 vibrational modes respectively. The former is a resonance feature associated with a large proportion of paired sp2 sites, while the latter is a weighted vibrational density-of-states for the distorted random network of sp3 sites. The position and relative intensity of the two peaks are shown to be strongly correlated with the percentage of sp3 sites in the films, providing a reliable measure of sp3 bonding which is both quantitative and non-destructive.
High-Pressure Chemistry of Carbon Nitride Materials
Authors: Stevens Andrew J. , Agee Carl B. , Lieber Charles M. 
Published: April 2011

ABSTRACTThe composition and properties of the sp2-bonded carbon nitride precursor paracyanogen (pCN) has been studied at high pressures and temperatures. Paracyanogen decomposes to carbon and molecular nitrogen with the decomposition temperature increasing with pressure over the range of 3 to 19 GPa. Prior to decomposition, pCN can be transformed to an atmospheric-pressure quenchable phase that is more than 25% higher in density and over an order of magnitude harder than the starting material. Structural analysis of this quenchable phase shows, however, that it consists of a sp2-bonded network. In addition, the decomposition kinetics of paracyanogen have been studied in detail. Rapid, self-propagating decomposition occurs above a threshold temperature. Below this, decomposition rates exhibit an Arrhenius behavior with activation energy and volume of 2.7 eV and 3.9 Å3, respectively The decomposition rates depend on the nitrogen density and decrease significantly with lower nitrogen concentration. Kinetic effects favoring a graphite-like, sp2-bonded structure may preclude the high-pressure synthesis of superhard, sp3-bonded carbon nitride solids below their thermodynamic stability limit, unless an optimally designed precursor is employed.
High Pressure and High Temperature Equation-of-State of Gamma and Liquid Iron
Authors: Chen George Q. , Ahrens Thomas J. 
Published: April 2011

ABSTRACTShock-wave experiments on pure iron preheated to 1573 K were conducted in the 17–73 GPa range. The shock-wave equation of state of γ-iron at an initial temperature of 1573 K can be fit with us = 4.102 (0.015) km/s + 1.610(0.014) up with ρo = 7.413±0.012 Mg/m3 We obtain for γ-iron's bulk modulus and pressure derivative the values: 124.7±1.1 GPa and 5.44±0.06, respectively.We present new data for sound velocities in the γ- and liquid-phases. In the γ-phase, to a first approximation, the longitudinal sound velocity is linear with respect to density: Vp = −3.13 (0.72) + 1.119(0.084) p(units for Vp and p are km/s and Mg/m3, respectively). Melting was observed in the highest pressure (about 70–73 GPa) experiments at a calculated shock temperature of 2775±160 K. This result is consistent with a previously calculated melting curve (for ε-iron) which is close to those measured by Boehler [1] and Saxena et al. [2]. The liquid iron sound velocity data yields a Grüneisen parameter value of 1.63±0.28 at 9.37±0.02 Mg/m3 at 71.6 GPa. The quantity γρ is 15.2±2.6 Mg/m3, which agrees with the uncertainty bounds of Brown and McQueen [3] (13.3–19.6 Mg/m3). Based on upward pressure and temperature extrapolation of the melting curve of γ-iron, the estimated inner core-outer core boundary temperature is 5500±400 K, the temperature at the core-mantle boundary on the outer core side is 3930±630 K.
Stabilization and transformation of the phases in nanostructured irconia prepared by wet chemical synthesis route
Authors: Xiaol T. D. , Bokhimi X. , Garcia-Ruiz A. , Morales A. , Wang D. M. , Chen H. , Struttl P. R. 
Published: April 2011

ABSTRACTNanostructured yttrium stabilized zirconia powders with yttria concentrations between 0.0 and 10.0 mol % were prepared via an aqueous chemical synthesis route. This synthesis involved the spray atomization of the aqueous solution mixture of zirconyl chloride and yttrium chloride into a reaction vessel that contained a diluted ammonium hydroxide, followed by ultrasonication, separation and heat treatment. These powders were characterized using SEM, TEM, XRD, and chemical analysis. The crystalline structure was refined using the Rietveld technique. At temperatures below 200 °C, the powders were amorphous solid solutions with an structure independent of yttria concentration, where yttrium atoms occupied the zirconium positions in the zirconyl group, e.g., (Zr4(1-x) Y4x(OH)8(OH2)16)(8-4x)+. Annealing the sample at 400 °C, the amorphous phases crystallized into monoclinic, tetragonal or cubic nanocrystalline zirconia, depending on yttria concentration, where the non-doped samples had a mixture of monoclinic and tetragonal phases.
Mechanisms of Energy Transfer in Solids Irradiated with Swift Heavy Ions
Authors: Szenes G. 
Published: April 2011

ABSTRACTThe damage cross section velocity effect is studied in LiNbO3, Y3Fe5O12 and SiO2 α-quartz. The application of our thermal spike model reveals that the efficiency of track formation varies by a factor of two in the range of 2–4 MeV/nucleon. The effect is explained by the varying fraction of energy deposition to the lattice involving lattice ions.
Ion Beam Mixing and Thermal Demixing of Co/Cu Multilayers
Authors: Cai M. , Veres T. , Cochrane R. W. , Roorda S. , Abdouche R. , Sutton M. 
Published: April 2011

ABSTRACTX-ray reflectivity and magnetotransport studies have been used to probe the effects of ion-beam irradiation and subsequent thermal annealing on the structure and giant magnetoresistance (GMR) in Co/Cu multilayers. Low-dose ion bombardment produces interfacial mixing which is accompanied by a systematic suppression of the anti ferromagnetic (AF) coupling and the GMR. For ion doses not exceeding 5 × 1014 ions/cm2, subsequent thermal annealing restores the abrupt interlayer structure as well as the GMR. The combination of low-dose ion bombardment and thermal annealing provides an ex situ technique to modify interface structure reversibly over a gnificant range.
Growth and Structure of in-plane Textured MgO Thin Films Deposited on Amorphous Substrates using ion-beam-assisted E-Beam Evaporation
Authors: Wang Connie P. , Do Khiem B. , Marshall Ann F. , Geballe Theodore H. , Beasley Malcolm R. , Hammond Robert H. 
Published: April 2011

ABSTRACTIn-plane aligned MgO thin films (∼100Å) have been obtained on various amorphous substrates by Ar+ ion-assisted electron-beam evaporation. Based on RHEED and cross-section TEM, we have shown that the MgO texture appears at a very early stage of film growth and is optimized at a thickness of around 100Å. Optimal thickness is the stage at which the surface is fully covered by MgO crystallites. The planar-view TEM of grain structure evolution in samples at different stages of growth reveals the dynamics of the texture developing process. Small, (100)-faceted MgO grains were observed both in planar-view and cross-section TEM images.
Mechanisms of Formation of Nonlinear Optical Light Guide Structures in Metal Cluster Composites Produced by Ion Beam Implantation
Authors: Sarkisov S. S. , Williams E. K. , Curley M. J. , Smith C. C. , Ila D. , Venkateswarlu P. , Poker D. B. , Hensley D. K. 
Published: April 2011

ABSTRACTWe report the results of characterization of linear and nonlinear optical properties of a light guide structure produced by MeV Ag ion implantation of LiNbO3 crystal (z-cut) in relation to the mechanisms of formation.
Control of Optical Performance from Er-Doped Alumina Synthesized Using An Ecr Plasma
Authors: Barbour J. C. , Potter B. G. 
Published: April 2011

ABSTRACTHydrogen in deposited optical ceramics can modify the optical properties, and therefore the role of the hydrogen needs to be understood to control its effects. Erbium-doped amorphous alumina films were deposited using simultaneous electron beam evaporation of aluminum and erbium while bombarding the sample with 30 eV 02+ ions from an electron cyclotron resonance (ECR) plasma. The hydrogen content was measured, using elastic recoil detection, as a function of isochronal annealing treatments. The data was fit to a simple trap-release model in order to determine an effective activation energy for the thermal release of H from alumina and Er-doped alumina. The intensity of the ion-beam stimulated luminescence from these samples was monitored in the visible and near infrared regions as a function of the thermal treatments. In order to gain a better understanding of the influence of hydrogen, the ionoluminescence (IL) data from samples containing hydrogen were fit with a simple linear equation.
Does the Latent Track Occurrence in Amorphous Materials Result from a Transient Thermal Process?
Authors: Toulemonde M. , Dufour Ch. , Paumier E. , Pawlak F. 
Published: April 2011

ABSTRACTHeavy ion irradiations in the electronic stopping power (Se.) regime have been performed in amorphous materials. Latent tracks have been observed in amorphous semiconductors (a-Ge, a-Si) and their radii have been deduced from a phenomenological analysis in an amorphous metallic alloy, in vitreous silica and “polymer” like amorphous carbon. A transient thermal model is developed describing the energy diffusion by the electron gas, by the atomic lattice and the energy exchange between the two subsystems. According to Fick's law, the classical equations of heat flow in the two subsystems (electrons and atoms) are numerically solved in a cylindrical geometry taking into account the temperature dependence of all the parameters. A simulation of annealing of nuclear collisions induced defects in crystalline iron allows to determine a local temperature. Electronic defect creation occurs when Se. increases and becomes larger than a threshold which is correlated with the appearance of a molten phase. Using such a criterion, the radii of latent tracks are reproduced in both a - Ge and a - Si with the same value of the electron-phonon coupling despite large differences in their lattice thermodynamic parameters. Such a model is applied to amorphous metallic alloy Fe85B15, vitreous silica and amorphous carbon.
Influence of Oxygen on Er-Related Emission in Gan With a Large Yellow Band
Authors: Ueklsa S. , Goto T. , Kumagai Mv. 
Published: April 2011

AbstractIn order to investigate the luminescence properties of Er3+in GaN and the effect of oxygen (O) on Er3+ -related emission in GaN:Er, erbium (Er) ions were implanted into single-crystal h-GaN grown on a c-axis sapphire substrate at an energy of 2MeV. Oxygen ions were subsequently coiniplanted into GaN with Er ions. The influence of oxygen on Er-related emission in GaN with a large yellow band was studied by comparing photoluminescence (PL) measurements of GaN:Er and GaN:ErO. It was found that the optimum annealing temperature to obtain maximum PL intensity was 1200°C and that the E3+a-related PL intensities from GaN:ErO samples were negligibly enhanced in comparison with the GaN:Er samples. The temperature dependence of PL intensity in GaN:ErO showed no appreciable difference from that of GaN:Er. But good correlation between Er-related and a large yellow band emission was observed in GaN. This indicates that codoped oxygen ions influence Er-related and yellow band emission in GaN
Fast Redistribution of Boron Impurity in Si During Ion Irradiation
Authors: Buzynin A.N. , Luk’yanov A.E. , Osiko V.V. , Voronkov V.V. 
Published: April 2011

AbstractThe model of point defects-induced inversion of conductivity, formation and movement of the inverted p-n junction during Ar+ ions irradiation of p-Si crystals is presented.
Electrons and Defects in Semiconductors
Authors: Queisser H.J. 
Published: April 2011

AbstractThis review addresses the centennial of the identification of the electron as the unit charge particle as well as the golden anniversary of the first demonstration of transistor action in a semiconductor material. Surprising skepticism arose in the acceptance of the quantized nature of the electric fluid; and formidable hurdles were encountered by the early generations of transistors. These obstacles are difficult to understand today. The transistor demonstration initiated research leading to highly perfected semiconductors. These materials can today be utilized toward precision measurements of fundamental quantities, such as the elementary charge by the quantum Hall effect, or the electron's effective spin magnetic moments by spectroscopy of quantum beats. Electrons and holes represent particle-antiparticle pairs in semiconductors with strong photon interactions, much like the fundamental lepton particles, for which a speculation on an evolutionary origin is presented. The unexpectedly long life of injected excess minority carriers in germanium established lifetime as the essential quantitative measure for materials quality and initiated massive and successful research on semiconductor defects.
Smart-Cut® Technology: an Industrial Application of Ion Implantation Induced Cavities
Authors: Aspar B. , Lagahe C. , Moriceau H. , Soubie A. , Bruel M. , Auberton-Hervé A.J. , Barge T. , Maleville C. 
Published: April 2011

AbstractThe Smart-Cut® process is based on proton implantation and wafer bonding. Proton implantation enables delamination of a thin layer from a thick substrate to be achieved whereas the wafer bonding technique enables different multilayer structures to be achieved by transferring the delaminated layer onto a second substrate. One of the best known applications of Smart Cut® is the Silicon On Insulator structure. The physical mechanisms involved in the delamination process are discussed based on the study of Proton-induced microcavity formation during implantation and growth during annealing. The experimental results on the time and temperature required to achieve delamination lead to different activation energies depending on the implantation conditions and resistivity of the substrate. All the experiments indicate that growth of microcavities is mainly controlled by hydrogen diffusion. The growth of these microcavities and the pressure inside them induce delamination when the catastrophic radius of the microcavities is reached.
Comparison of Device Performance Fabricated on Thick So and Bulk Wafers
Authors: Sasaki A. , Mitsuhida E. , Abe H. , Yoshii Y 
Published: April 2011

AbstractWe have investigated the surface quality of thick 10μm Silicon-On-Insulator (SOI) wafers by comparing CMOS device performance and reliability of SOI wafers with those of bulk wafers. Large scale CMOS circuits, microcontrollers with 12Kbyte ROM and 512byte EEPROM, were fabricated on thick SOI wafers and on bulk wafers, and device performance and reliability were evaluated by means of functional tests and acceleration tests. A significant difference was observed only in the ROM bit-map failure analysis in the functional tests, in which the number of single bit failures (defined as a chain of up to 4 adjacent bit failures) was more evident on ROM fabricated on the thick SOI than that fabricated on bulk wafers. The result indicates that the crystal defects introduced by the initial oxygen concentration and excess film stress of the SiO interlayer may cause single bit failures. The SOI wafers were prepared by Direct Wafer Bonding 2(DWB) and a mechanical polishing technique to form a 10μm active silicon layer and a 625μm silicon substrate, which sandwiches a 0.25μm SiO2 interlayer. Thick SOI wafers such as these are becoming a promising material for one-chip integration of CMOS devices and Micro Electrical Mechanical System (MEMS) devices.
The Impact of Rapid Thermal Annealing on the Properties of the Si (100)-SiO2 Interface
Authors: Hurley P.K. , Leveugle C. , Mathewson A. , Doyle D. , Whiston S. , Prendergast J. , Lundgren P. 
Published: April 2011

AbstractIn this work, we present results and analysis which demonstrate the influence of rapid thermal annealing (RTA) on the properties of the Si(100)-SiO2 interface. Polysilicon/oxide/silicon capacitor structures were subjected to RTA treatments, in a nitrogen ambient, over the temperature range 600-1050°C. The structures were examined using high frequency and quasi-static capacitance-voltage (CV) analysis to determine the interface state density profile across the energy gap immediately following the RTA step. The effect of hydrogen annealing subsequent to the RTA process is also presented. Based on the analysis of the interface state density profiles, it is suggested in this work, that RTA (T > 600°C) exposes silicon dangling bond (Pb) centres at the Si(100)-SiO2 interface. The implications of this work to the study of the Si-SiO2 interface, and the technological implications for silicon based MOS processes, are discussed.
Effects of Sputtering Conditions on Texture, Microstructure and Magnetic Properties of the CoCrPt/NiAl Thin Films
Authors: Hsu Y.-N. , Laughlin D. E. , Lambeth D. N. 
Published: April 2011

AbstractThe effects of sputtering argon pressures and sputtering power on the microstructure, texture and magnetic properties of NiAI underlayers on CoCrPt films were investigated. In this paper, the relationship between the sputtering conditions, microstructure, crystallographic texture and magnetic properties of these thin films will be discussed. By controlling the sputtering pressure and sputtering power, the texture and microstructure of NiAI underlayers were found to vary. This in turn was found to influence the magnetic properties of CoCrPt thin films. It was found that 10 mtorr is the optimum pressure to deposit the NiAl thin films to obtain the best magnetic properties for our system. At this argon pressure, the coercivity reached a maximum value because of the strongest CoCrPt (1010) texture and smallest grain size. At lower argon pressures (< 10 mtorr), NiAI tended to have a (110) texture reducing the CoCrPt (1010) texture, which in turn reduced the CoCrPt coercivity and S*. Also, high NiAl deposition pressures (>30 mtorr) yielded larger grains and a weaker CoCrPt (1010) texture, thereby decreasing the coercivity of the CoCrPt films. Increasing the sputtering power has been found to increase the CoCrPt coercivity and S* value. However, the grain sizes of the CoCrPt/NiAl thin films deposited at higher sputtering power were larger than those obtained at lower sputtering power.
Behavior of Magnetic Aftereffect Along a Magnetization Reversal Curve in a Metal Particle Recording Material
Authors: Swartzendruber L. J. , Bennett L.H. , Della Torre E. , Brown H.J. , Judy J.H. 
Published: April 2011

AbstractExperimental measurements of the aftereffect along a magnetization reversal curve are compared with the predictions of a Preisach-Arrhenius model for a high density particulate recording medium. The Preisach parameters are determined from the measurement of the major hysteresis loop and the remanence loop. The Arrhenius parameters were determined from a single aftereffect curve. It was then found that the model gives good qualitative agreement with both the initial slope and, for the case in which the aftereffect is not monotonic, the peak value of the aftereffect.
Observations of Depth-Sensing Reciprocating Scratch Tests of DLC and Nitrogenated-DLC Overcoats on Magnetic Disks
Authors: Scharf T.W. , Ott R.D. , Yang D. , Barnard J.A. 
Published: April 2011

AbstractIn this investigation, the wear durability of existing and candidate protective overcoats and substrates was examined. Specifically, 5 nm thick diamond-like carbon (DLC) and nitrogenated diamond-like carbon (N-DLC) overcoats were deposited by sputtering onto glass, glass-ceramic, and NiP/AlMg substrates. The magnetic medium was a 15 nm thick layer of CoCrPt deposited on a 50 nm thick underlayer of CrV. The wear resistance of the hard disks was determined by a recently developed depth sensing reciprocating scratch test using the Nano Indenter© II. During the scratch tests, a constant normal load of 30 jtN was maintained at an indenter velocity of 2μm/sec. It was found the N-DLC/CoCrPt/CrV/glass disk exhibited the most wear resistance and least amount of plastic deformation after the last wear event. Conversely, the NDLC/CoCrPt/CrV/NiP/AiMg disk displayed the least wear resistance even though the magnitude of the elastic recovery was the greatest. This amount of recovery was influenced by the high elastic modulus of the NiP/AIMg substrate. Consequently, the scratch test failed to isolate the intrinsic properties of the overcoat, however it provided a very powerful means of quantitatively assessing the overall response of the whole magnetic disk. This is more relevant since it simulates the response the disks see in performance. In addition, a discrete amount of nitrogen up to 14 atomic % incorporated into the amorphous network resulted in an increase in overcoat durability compared to the DLC overcoat. This was attributed to an increase in the XPS determined number of N-sp3 C bonded sites in a predominantly N-sp2 C bonded matrix. However, with increasing nitrogen concentrations ≥18%, the film structure was weakened due to the micro-Raman spectroscopy determined formation of terminated sites in the amorphous carbon network since nitrogen failed to connect the sp2 domains within the network.
The 1280 Cm−1 Absorption Line in Amorphous Hydrogenated Boron Carbide
Authors: Lin Shu-Han , Feldman Bernard J. 
Published: April 2011

AbstractWe report infrared absorption measurements that provide evidence for the presence of boron carbide icosahedra in amorphous hydrogenated boron carbide thin films. The infrared absorption spectra is dominated by an intense line at 1280 cm-1 with a FWHM of ≃320 cm-1. Similar lines have been previously reported in polycrystalline boron carbide, where boron carbide icosahedra make up the unit cell. In both systems, the linewidth narrows and the peak position shifts to higher energy with increasing carbon concentrations. From annealing studies of amorphous hydrogenated boron carbide, hydrogen plays a very small role in the 1280 cm-1 line. Finally, the integrated intensity of the 1280 cm-1 line is a sublinear function of the boron concentration, providing further evidence that the carbon concentration in these icosahedra increases as the carbon concentration of the film increases.
Characterizing the Magneto-optic Properties of Amorphous Rare Earth - Transition Metal Thin Films
Authors: Challener W. A. 
Published: April 2011

AbstractThe amorphous rare earth - transition metal (RE-TM) thin film alloys and nanolayered materials exhibit numerous properties advantageous for optical recording, including perpendicular anisotropy, high coercivity and low magnetization at room temperature, low noise, and easily adjustable Curie and compensation points. As a result these materials have been employed in all commercial magneto-optic (MO) media. On the other hand, the MO effect of these materials is relatively small and tends to decrease with decreasing wavelength. It is important to understand the useful limits of these materials in MO media, and to determine if their MO figure of merit can be substantially increased through appropriate doping or nanolayering. In this paper we discuss experimental techniques for measuring MO properties, a theoretical approach for analyzing the data and designing optical thin film stacks, and results for a variety of RE-TM thin film materials.