bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization Of SiC Films Deposited By Laser Ablation Technique For X-Ray Membranes
Authors: El Khakani M.A. , Chaker M. , Boily S. , Papadopoullos A. , Huai Y. , Jean A. 
Published: March 2011

AbstractLaser Ablation Deposition (LAD) technique was used to produce hydrogen-free SiC films on (100) Si substrate. Deposition temperatures of 300°C and 450°C were investigated. The Si2p and C1s. core levels and the Si-C absorption band of the a-SiC LAD films were characterized by using X-ray Photoelectron Spectroscopy (XPS) and Fourier-Transform Infra Red (FTIR) absorption spectroscopy, respectively. The high compressive stress of the as-deposited SiC films was released and controlled by means of rapid thermal annealing. A correlation between the stress evolution and the Si-C bond density of the annealed films is pointed out. Optical transmission and mechanical properties (stress, Young's modulus) measurements were carried out on the free-standing membranes fabricated from SiC LAD films. The effect of the deposition temperature on the SiC membrane properties is discussed.
X-Ray Lithography Induced Radiation Effects In Deep Submicron Cmos Devices
Authors: Wang L.K. , Acovic A. , Chang W.H. 
Published: March 2011

AbstractX-ray lithography introduces device radiation damage from the high energy photons during the lithography process. We have studied this effect on deep submicron n- and p-channel MOSFETs with gate dielectric thickness at 7 to 13 nm. After the x-ray irradiation the device characteristics are strongly affected by the generation of oxide charges, interface states and electron traps. These introduced damages cause the reduction of device transconductance, shift of the threshold voltages and increased leakage current. However, this degradation of device and circuit is lessened from technology scaling by thinning the gate oxide and lowering the supply voltage. The x-ray radiation damage, induces interface states and oxide charges which can be annealed out with a low temperature (400°C) forming gas (FG, 90% N2, 10% H2) annealing process. The device properties are essential unchanged after the annealing process. However, the residue damage is shown to enhance hot-carrier instability of p-channel devices if the remaining neutral traps act as electron or hole traps in the SiO2. In this paper, we investigate the radiation effects on the n- and p-channel MOSFETS fabricated with deep submicron device processes with thinner gate oxides and compare the hot carrier reliability of these devices after the synchrotron x-ray irradiation and also after the post metal forming gas annealing. The results indicate the device hot carrier instability has no effect on the devices with thin gate oxide with thickness approaching the electron tunneling range.
Modelling Photoelectron Effects In X-Ray Lithography
Authors: Ocola L. E. , Cerrina F. 
Published: March 2011

AbstractThe study of photoelectron effects in X-ray Lithography motivates the need for modeling codes to simulate these effects to have an estimate of the influence of x-ray generated photoelectrons in the exposure of resists. We have performed a series of Monte Carlo simulations to study the spatial distribution of photoelectrons in a resist, PMMA, and parametrized this distribution with a set of energy-dependent gaussians for monochromatic X-rays within an energy range of 0.5 KeV to 2.5 KeV. We discuss the effects of the the redistribution of the photoelectron kinetic energy as a function of the electrons generated by the x-ray absorption in various atomic species.
Materials And Fabrication Processes For Highly Accurate X-Ray Masks
Authors: Oda Masatoshi , Yoshihara Hideo 
Published: March 2011

AbstractThis paper discusses the properties of materials for x-ray masks used in synchrotron radiation lithography system. Through computer simulations and experimental analysis, we evaluate three kinds of membranes (Si, SiN, SiC) in terms of mechanical distortions, surface smoothness and optical transmittance. SiC exhibits the smallest distortion, but SiN has the best characteristics in the surface smoothness and the optical transmittance. By virtue of their high x-ray absorption coefficient and dry etching capabilities, Ta, W and Re are selected as potential absorber materials. We study their stress control characteristics, etching characteristics and the relation between their Young's modulus and distortions. We find that Ta is an excellent absorber because of its good stress controllability and good etching characteristics, such as a high etch rate and etch selectivity. By adopting a Ta/SiN structure, highly accurate masks can be fabricated by a process in which patterning the absorber is carried out before removing the bulk Si.
Magnetic Circular Dichroism in X-Ray Fluorescence
Authors: Duda L.-C. , Hague C. F. , Mancini D. C. , Mariot J.-M. , Marliere C. , Nordgren J. , Skytt P. , Wassdahl N. 
Published: March 2011

ABSTRACTX-ray fluorescence spectra from magnetized iron excited by circularly polarized synchrotron radiation are reported. The Fe L2.3 emission band gives rise to a distinct dichroic signal in confirmation of a recent theoretical prediction. These preliminary experiments carried out with “white” and only partially circularly-polarized synchrotron radiation nevertheless reveal an asymmetry which reflects the spin polarization of the Fe 3d valence electrons. The usefulness of developing specialized high flux circularly-polarized sources is clearly established.
A Soft X-Ray Photoemission Study of the Chemisorption and Reaction of Diethylsilane on SI(100)
Authors: Lapiano-Smith D. A. , Himpsel F. J. , Terminello L. J. 
Published: March 2011

ABSTRACTSoft x-ray synchrotron radiation has been utilized as the excitation source in a high-resolution photoemission experiment designed to investigate the chemisorption and subsequent reaction of diethylsilane on the technologically important Si(100) surface. We have found that diethylsilane chemisorbs dissociatively to form Si-CH2CH3 surface species on Si(100) following a room temperature exposure. These species are identified by two very sharp peaks observed in the valence band spectra positioned at 17.9 and 14.3 eV binding energy. In addition, C Is core level spectra, measured following exposures of Si(100) substrates as a function of surface temperature, show that carbon, in some form, exists on the Si surface following exposures at every temperature from room temperature to about 600°C. While only -CH2CH3 ethyl groups are observed on the surface at room temperature, these species appear to partially dehydrogenate at 300°C, producing a mixture of -CH2CH3 groups and other intermediate carbonaceous species. At a growth temperature of about 400°C the intermixing of elemental carbon with Si begins. At higher temperatures, we observe the continued degradation of diethylsilane to produce a Si + C alloy on the surface at 600°C. Our results indicate that diethylsilane has potential as a molecular precursor for SiC formation by chemical vapor deposition techniques.
Soft X-Ray Photoelectron Spectroscopy Of Bi-Metallic Interfacial Bonding
Authors: Shinn N. D. , Kim B. , Andrews A. B. , Erskine J. L. , Kim K. J , Kang T.-H. 
Published: March 2011

ABSTRACTWe report the first application of Soft X-ray Photoelectron Spectroscopy (SXPS) to probe the bonding at epitaxial, bi-metallic interfaces with atomic-layer spatial selectivity. Specifically, we have measured the W(4f)7/2 levels of interfacial tungsten atoms for (1×1)Fe/W(110), (1×1)Ni/W(110), and (1×1)PtW(110). For clean W(110), the surface atoms exhibit a W(4f)7/2 peak at -320 meV binding energy with respect to the bulk W(4f)7/2 peak. Upon formation of the metallic overlayers, the interfacial tungsten atoms contribute W(4f)7/2 peaks at -225 meV (Fe/W), -140 meV (Ni/W), and +70 meV (Pt/W) with respect to the bulk W(4f)7/2 peak. The systematic reduction in the binding energy difference between interfacial and bulk tungsten atoms for Fe, Ni, and Pt correlates with increasing heats of adsorption on W(110), as determined by Temperature Programmed Desorption. This suggests that SXPS, in combination with first principles calculations and Born-Haber thermochemical cycle analyses, can be used as a non-destructive probe of bi-metallic interfacial bonding energies.
High Energy Resolution Arpes Measurements of the Normal and Superconducting States of Bi2Sr2CaCu2O8+δ
Authors: Dessau D. S. , Shen Z.-X. , King D. M. , Wells B. O. , Marshall D. S. , Lombardo L. W. , Dickinson P. H. , Dicarlo J. , Park C.-H. , Loeser A. G. , Kapitulnik A. , Spicer W. E. , Arko A. J. 
Published: March 2011

ABSTRACTThe near-EF electronic structure and Fermi surface of Bi2212 has been mapped out with ARPES. A key feature of our measured bandstructure is the existence of an extended region of flat CuO2-derived bands at EF. Comparative analysis of this data with that from NdCeCuO and YBCO7 suggests that many of the anomalous (normal) physical properties of Bi2212 and YBCO7 (NdCeCuO) may be related to the existence (absence) of such bands at EF. Superconducting gap anisotropy at least an order of magnitude larger than that of the conventional superconductors has been observed in the a-b plane of Bi2212 in ARPES. For samples with Tc of 88K, the gap size reaches a maximum of approximately 20 meV along the Cu-O bond direction, and a minimum of much smaller or vanishing magnitude 45° away. The experimental data is discussed within the context of various theoretical models. In particular, a detailed comparison with what is expected from a superconductor with a dx2-y2 order parameter is carried out, yielding a consistent picture.
Narrow-Band Synchrotron Radiation Excitation of Soft X-Ray Emission Spectra
Authors: Miyano K. E. , O'Brien W. L. , Ederer D. L. , Callcott T. A. , Jia J. J. , Dong Q.-Y. , Zhou L. , Woicik J. C. , Mueller D D. R. 
Published: March 2011

ABSTRACTMonochromatized synchrotron radiation has been employed as the excitation source for soft x-ray emission spectroscopy. In the present paper changes in the emission spectra that occur as the excitation energy is varied near the core-absorption threshold are discussed. In the case of crystalline silicon, strong variations are seen in the L2,3 emission for excitation energies up to 30 eV above threshold. These variations are shown to be dependent on the crystalline order of the material and can be interpreted in terms of restrictions on the crystal momentum that arise in an inelastic scattering description of the combined absorption and emission. On the other hand this description is less relevant to the excitation-energy dependence of ionic insulators, in which strong phonon coupling removes these restrictions on crystal momentum. In the insulators B2O3 and BN strong variations in the emission are observed at threshold, upon creation of a core exciton: the exciton affects the emission through its influence on the phonon coupling as well as on the initial and final-state screening.
The Changing Environments of Dopants in Amorphous Silicon at Various Stages of Annealing
Authors: Dent Andrew J. , Dobson B. R. , Greaves G. N. , Kalbitzer S. , Derst G. , Müller G. 
Published: March 2011

ABSTRACTX-ray Absorption Fine Structure (XAFS) spectroscopy measured at glancing angles of incidence has been used to record the varying environments of Ga and As ion-implanted in amorphous silicon at dose levels of 4 1014 atoms cm-2. Both glow discharge deposited films and silicon wafers previously amorphised by ion beam damage were used and apart from small differences relating to the presence of hydrogen in the former the environments of the same impurity in the two forms of amorphous Si were almost indistinguishable for the same beat treatment. The fact that only glow discharge deposited material is electronically active points to differences in the intrinsic defects in these two forms of a-Si. The local atomic structure of impurities in as-implanted specimens, however, was found to alter significantly with annealing. By 400°C, for instance the coordination numbers of both Ga and As approach 3 Si's indicating very few tetrahedral sites are present in the amorphous state. By 700°C, however, the coordination numbers of either impurity Ga and As have increased and the crystallisation local to the impurities can be detected in the XAFS by the appearance of outer shells of atoms. The fraction of crystalline substitutional sites, however, is only around 33% even though the thermal epitaxial regrowth of the remaining Si matrix is practically complete. Recrystallisation of Si is clearly inhibited in the vicinity of dopants by the persistence of 3-fold sites.
Synchrotron White Radiation X-Ray Topographic Investigation of Dislocation Configurations Developed in Indium Antimonide Single Crystals by Plastic Bending
Authors: Wu Jun , Dudley M. 
Published: March 2011

ABSTRACTSynchrotron white beam x-ray topography has been used to study dislocation configurations induced in InSb single crystals by three point bending at temperatures above the brittle to ductile transition point. Semi-hexagonal dislocation loops with one long screw segment and two outcropping 60° segments, single 60° B(g) dislocation kinks on screw dislocations, and screw dislocation dipoles were observed. The relationship between these observed defect structures and the mobilities of A(g), B(g), and screw dislocations in InSb, which appear to control the plastic behavior of crystals with the sphalerite structure, is discussed. Dislocation interactions and their role in the plastic deformation process are also addressed.
Synchrotron X-Ray Topographic Study of Defects in High Quality, Flux Grown Ktiopo4 Single Crystals
Authors: Wang S. , Dudley M. , Cheng L. K. , Bierlein J. D. 
Published: March 2011

ABSTRACTDefect structures in large, high quality flux-grown KTP single crystals have been studied by using synchrotron white beam X-ray topography. Growth dislocations, inclusions, growth sector boundaries, growth bands and surface micro-scratches were imaged. A number of planar defects in the dislocation-free region are imaged and determined to be inversion twin lamellae (lamellar ferroelectric domains) which have never been previously reported in KTP crystals. These inversion twin lamellae were also studied by section topography. Detailed analysis of observed contrast revealed that the domain walls bounding the lamellae are faulted with a fault vector of ½[0±1±1]. This fault vector seems to be consistent with the atomic structure of KTP. A detailed analysis is presented and discussed.
Diffraction and Holography of Photoelectrons and Fluorescent X-Rays
Authors: Fadley Charles S. 
Published: March 2011

ABSTRACTPhotoelectron diffraction is by now a powerful technique for studying surface structures, with special capabilities for resolving chemical and magnetic states of atoms and deriving direct structural information from both forward scattering and backscattering. Fitting experiment to theory can lead to structural accuracies in the 0.03 Å range. Holographic inversions of such diffraction data also show considerable promise for deriving local three-dimensional structures around a given emitter with accuracies of 0.2-0.3 Å. Resolving the photoelectron spin in some way and using circularly polarized radiation for excitation provide added dimensions for the study of magnetic systems and chiral experimental geometries. Synchrotron radiation with the highest brightness and energy resolution, as well as variable polarization, is crucial to the full exploitation of these techniques. X-ray fluorescence holography also has promise for structural studies, but will require intense excitation sources and multichannel detection to be feasible.
Reconstruction of the 3-D Atomic Structure of CoSi2 (111) by Photoelectron Holography
Authors: Zhoul Y. , Chen X. , Campuzano J. C. , Jennings G. , Gofron K. , Ding H. , Saldin D. K. 
Published: March 2011

ABSTRACTWe report the use of photoelectron holography for the study of the atomic geometry of the (111) surface of single crystal CoSi2. We employ as a reference wave the Co 3p core electron emitted with a kinetic energy of 695 eV by absorption of synchrotron radiation. Remarkably sharp images of the nearest Si neighbors of the Co emitter were found using a computer reconstruction algorithm which compensates for the anisotropies of both reference and object waves. Comparison with other reconstruction schemes such as the Helmholtz-Kirchoff (HK) algorithm and the scattered-wave included Fourier transform (SWIFT), demonstrates the necessity of compensating for the reference-wave anisotropy.
Pre-Transitional Behavior in Cubic Potassium Niobate
Authors: Holma M. , Hong H. , Nelson M. , Chen Haydn 
Published: March 2011

ABSTRACTPre-transitional behavior prior to the onset of the cubic-to-tetragonal phase transformation in KnbO3 has been studied with synchrotron x-ray scattering at NSLS, Brookhaven National Lab. Measurements of the Thermal Diffuse Scattering (TDS), Grazing Incidence X-ray Scattering (GIXS), and precursor Bragg scattering have been performed at a series of temperatures on a single crystal sample in the cubic phase (Tc = 405 °C). The TDS was measured in the (001), (011) and (111) cubic planes. The GIXS was measured above, at and below the critical scattering angle of the sample. Based on localized soft mode theory, dynamic tetragonal fluctuations may be expected prior to the onset of the phase transition initiated by defects or surfaces. The GIXS data indicate that the tetragonal phase is apparent prior to the phase transition of the bulk - - consistent with the notion that nucleation originates from potent defect sites during a martensitic-like displacive transformation. The TDS intensity distribution is disk-shaped; arising from a localized, low energy transverse optic mode in the [100] directions extending out to the Brillouin zone boundary (reduced wave vector, q =0.5). Scans made in the (011) planes show TDS intensity extending out to a reduced wave vector of q ˜ 0.2. Preliminary analysis indicates that a low energy transverse optic mode extends in the [011] direction as well. The TDS intensity decreases as the transition temperature is approached from above. Comparison of the TDS results with inelastic neutron scattering data will be made.
Ab Initio XAFS and XANES Standards
Authors: Rehr J. J. , Zabinsky S. I. , Albers R. C. 
Published: March 2011

ABSTRACTAb initio x-ray-absorption fine structure (XAFS) and x-ray-absorption near edge structure (XANES) standards are developed for molecules and solids. These standard XAFS spectra are obtained from ab initio XAFS calculations, using an automated code, FEFF, which we have extended to include multiple-scattering (MS) and XANES calculations. Our treatment is based on state-of-the-art curved-wave MS theory. Sample results are presented and compared with experiment. We find that these theoretical standards are comparable with experimental measurements, yielding distance determinations better than 0.02 Å and coordination numbers better than 20%. Our approach also gives a new MS interpretation of the σ* shape-resonances in XANES.
New Techniques for Synchrotron Powder Diffraction Studies
Authors: Knapp G. S. , Beno M. A. , Jennings G. , Ramanathan M. 
Published: March 2011

ABSTRACTThis manuscript discusses two different powder diffraction methods which possess high resolution, low background and very high counting rates. Both methods utilize analyzer crystals in combination with position sensitive detectors. The first method uses a curved perfect crystal analyzer diffracting in the scattering plane to diffract a range of angles into the position sensitive detector. The second method is somewhat simpler, it uses a graphite analyzer crystal diffracting out of the scattering plane. Applications of these methods to anomalous scattering from both powder and amorphous materials are also discussed. One of the techniques should also be very useful for small angle scattering.
The Local Atomic Structure in Hg0.80Cd0. 20Te
Authors: Quintana J. P. 
Published: March 2011

ABSTRACTLocal atomic arrangements in Hg0.80Cd0. 20Te were investigated by measuring the diffuse x-ray scattering at two different energies near the HgLIII absorption edge to yield intensity due only to Hg-Hg, Hg-Te, and Hg-Cd pair interactions. The data were separated into short range order and displacement intensities. Simulation revealed ordered regions with 3:1 Hg-Cd near neighbor configurations. The Hg-Te length is contracted.
Anticlastic Curvature of Elastically Bent Crystals for Sagittal Focusing
Authors: Quintana J. P. , Kushnir V. I. , Georgopoulos P. 
Published: March 2011

ABSTRACTFinite element results are presented for the case of an elastically bent isotropic rectangular crystal with clamped boundary conditions. Results show that the anticlastic curvature can be eliminated in the center of the crystal provided the crystal length to width ratio fits a “golden aspect ratio” which is dependent on the Poisson coefficient ν. For ν=0.262 (appropriate for Si(111)), this ratio is approximately equal to 1.42.
EXAFS Studies on the Structure of Photoexcited Cyclopentadienylnickelnitrosyl(C5H5NiNO)
Authors: Chen Lin X. , Bowman Michael K. , Montano Pedro A. , Norris James R. 
Published: March 2011

ABSTRACTThe structures of C5H5NiNO in a reversible photochemical reaction were studied via EXAFS, FTIR, and optical absorption spectroscopies. A photoexcited intermediate with distinctively different EXAFS, IR, and optical absorption spectra from those of the ground state molecules was generated upon irradiation using 365 nm light at 20K in a 3-methylpentane solution. The reverse reaction was induced by irradiation with 310 nm light. The EXAFS data analysis has shown a 0. 12 Å elongation of the Ni-N bond and the bending of Ni-N-O in the photoexcited intermediate. Several ZINDO calculations were conducted based on the structures obtained from the EXAFS spectroscopy. These calculations reproduced the changes in the optical spectra and the intramolecular electron transfer in C5H5NiNO.
X-Ray Absorption Analysis of Ge and Ga Environments in Ba-Gallogermante Glasses
Authors: Merzbacher Celia I. , McKeown David A. 
Published: March 2011

ABSTRACTX-ray absorption spectroscopy has been used to characterize the local structure surrounding Ga and Ge in BaO-Ga2O3-GeO2 glasses. Based on comparisons with results for crystalline standards of known structure, Ge and Ga in all of the glasses are primarily in tetrahedral coordination; no evidence for octahedral coordination is observed. Bond length and coordination values derived from fitting calculations are fairly uniform for all glasses, however disorder increases with increase in BaO and decrease in GeO2 content, especially in the second shell surrounding Ge and Ga. Ge absorption edges for all glasses resemble smoothed BGG-An or GeO2 [quartz] edges. Ga absorption edges of the glasses also resemble the BGG-An edge which has two edge maxima, but in the glasses the relative intensities of the two maxima vary with composition.
X-Ray Absorption Spectroscopy of the Rare Earth Orthophosphates
Authors: Shuh D. K. , Terminello L. J. , Boatner L. A. , Abraham M. M. 
Published: March 2011

ABSTRACTX-ray Absorption Spectroscopy (XAS) of the Rare Earth (RE) 3d levels yields sharp peaks near the edges as a result of strong, quasi-atomic 3d104fn→3d94fn+1 transitions and these transitions exhibit a wealth of spectroscopic features. The XAS measurements of single crystal REPO4 (RE = La, Ce, Pr, Nd, Sm, Eu, Gd, Th, Dy, Er) at the 3d edge were performed in the total yield mode at beam line 8–2 at the Stanford Synchrotron Radiation Laboratory (SSRL). The XAS spectra of the RE ions in the orthophosphate matrix generally resemble the XAS of the corresponding RE metal. This is not unexpected and emphasizes the major contribution of the trivalent state to the electronic transitions at the RE 3d edges. These spectra unequivocally identify the transitions originating from well-characterized RE cores and correlate well with previous theoretical investigations.