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We present a theoretical study of bichromatic weakly non-collinear Airy-type waves propagating with various amplitudes in water of infinite depth. The coupled nonlinear Schrödinger equations are invoked to study the behavior of self- and cross-interacting Airy wave packets. We demonstrate that bichromatic pulses possess the main properties of single Airy wave packets—shape invariance and self-acceleration or self-deceleration—when propagating in a dispersive medium. Accounting for nonlinearity leads to a strong dependence of the structure, stability, and propagation velocity of wave pulses on their amplitude. We show that interacting pulses of Airy-type waves can form giant accelerating and decelerating waves. [ABSTRACT FROM AUTHOR]

In this article, we investigate extensively the bipolar-switching properties of Al2O3- and HfO2- based resistive-switching memory cells operated at low current down to <1 μA. We show that the switching characteristics differ considerably from those typically reported for larger current range (>15 μA), which we relate as intrinsic to soft-breakdown (SBD) regime. We evidence a larger impact of the used switching-oxide in this current range, due to lower density of oxygen-vacancy (Vo) defects in the SBD regime. In this respect, deep resetting and large memory window may be achieved using the stoichiometric Al2O3 material due to efficient Vo annihilation, although no complete erasure of the conductive-filament (CF) is obtained. We finally emphasize that the conduction may be described by a quantum point-contact (QPC) model down to very low current level where only a few Vo defects compose the QPC constriction. The large switching variability inherent to this latter aspect is mitigated by CF shape tuning through adequate engineering of an Al2O3\HfO2 bilayer. [ABSTRACT FROM AUTHOR]

Applying a cost-effective process with a simple one-side-heating furnace, two layers of YBa2Cu3Ox (YBCO) bulks were successfully grown in one batch by using NdBa2Cu3Ox (NdBCO) thin-film-seeds deposited on MgO substrates. Due to the large temperature difference between the two layers, the seed-induced growth began at the bottom layer much later than that at the top layer. Remarkably, NdBCO films on the bottom layer samples survived a long time (over 15 h) above the growth temperature and effectively induced the YBCO growth. The significant thermal stability of the films, i.e., the tolerance for a long holding time on the surface of the molten pellet, is supposed to relate to a competition between the dissolution/diffusion of film materials into the liquid and NdBCO grain coarsening/Nd-YBCO crystallization. [ABSTRACT FROM AUTHOR]

The effect of oxygen partial pressure on the thermal stability of Nd-123 superconductor thin films was investigated by means of high temperature in situ microscopy. It was found that the thermal stability of Nd-123 films decreases as the oxygen partial pressure increases. We attribute the thermal stability suppression to the increased growth rate of Nd-422 and a high concentration difference ratio. Under the assumption of quasi-equilibrium, a simplified model for peritectic melting of RE-123 was suggested. [ABSTRACT FROM AUTHOR]

From the low-temperature (down to 10 K) dc-magnetization data of the La0.7Sr0.3MnO3 (LSM), La0.7Ca0.3MnO3 (LCM), and Pr0.7Ca0.3MnO3 (PCM) systems, we estimated the critical exponents β, γ, and hence δ from the analysis of the modified Arrot plots. The exponent β estimated for the LCM system is less than that predicted by Heisenberg model and resides within the zone predicted by Ising model while for the LSM sample, β is higher than that predicted from the Heisenberg model which is considered to be due to the presence of dipole-dipole interaction arising from the large spin moment in the LSM system. The magnetization data of the PCM system cannot be fitted to the modified Arrot plots, which suggest highly inhomogeneous ground state even under 5 T magnetic field. Both LSM and LCM have almost equal values of γ. Seebeck coefficient data indicate a crossover from higher-temperature n-type to lower-temperature p-type conductivity behavior in both LSM and LCM systems, while the semiconducting PCM system shows p-type conductivity throughout the temperature range (300–80 K). It is noticed that for LSM system TC (Curie temperature) and TMI (metal-insulator transition temperature) are almost equal (∼360 K), whereas for the LCM system there exist a large difference between TC and TMI (TC∼245 K and TMI∼265 K), which may give some idea regarding the critical behavior of the respective samples. [ABSTRACT FROM AUTHOR]

Transport properties (resistivity and thermoelectric power) of Pb doped LaNiO3 viz. La1-xPbxNiO3-δ (0.0<=x<=0.1) show metallic behavior over a wide range of temperature (10–550 K). Pb doping (up to 10%) at the La site does not destroy the metallic behavior of LaNiO3. The paramagnetic susceptibility χ decreases with Pb doping. Above 50 K, χ is almost temperature independent and exhibits Pauli like features with a small additional Curie law contribution. The resistivity ρ increases with Pb doping though the thermoelectric power does not change proportionately, indicating that Pb doping does not introduce much disorder in the system. A linear T dependence of ρ observed above 150 K suggests the importance of electron–phonon (el–ph) interactions but at temperature below 150 K, ρ follows a T1.5 dependence. The estimated el–ph interaction constant λ increases (0.80–2.53) with Pb doping (x=0.0–0.1). No saturation of resistivity has been observed even up to 550 K with x<=0.1. The phonon frequency νph∼3444 cm-1 of the undoped sample calculated from the absorption peak of the Fourier transform infrared spectra agrees well with that at ∼3025 cm-1 estimated from the reported heat capacity data. [ABSTRACT FROM AUTHOR]

Hydrostatic-pressure (up to 0.96 GPa) dependence of Tc in a newly discovered Fe-based superconductor (Tl0.59Cs0.26)Fe1.9Se2 (Tc = 28 K, at ambient pressure) is reported. Static magnetization measurements under pressure indicate that the linear increase in Tc is initially rapid (dTc/dP ∼ 9.9 K · GPa-1) but slows down to dTc/dP ∼ 2.5 K · GPa-1 for P ≧ 0.18 GPa. The Tc of the superconducting phase is 32 K at pressure P = 0.96 GPa. The simple rigid band model or the Bardeen, Cooper, Schrieffer theory may not be sufficient to account for our observations, if one assumes that the lattice parameters would be linearly decreased with pressure. [ABSTRACT FROM AUTHOR]

The magnetic-induced dielectric responses of BiFeO3 (BFO) thin films were measured at the X-band microwave frequency ranged from 7 to 12.5 GHz. The measurement was given initially by a high-precision cavity microwave resonator without magnetic field. Both the real and imaginary parts of the permittivity showed its dielectric property as a function of the measuring frequency. The X-band dielectric responses of the BFO thin film were then measured by a controlled magnetic field at room temperature. The data demonstrated up to 2.2% dielectric tunability by using only 3.46 kOe magnetic field at TE107 mode (9.97705 GHz). [ABSTRACT FROM AUTHOR]

Low temperature calorimetric measurements have been made on a series of binary aluminum alloys containing 1–10 at. % lithium. The heat capacity data are analyzed in terms of an electronic and a lattice contribution. Accordingly, the low level of lithium addition yields appreciable changes in the electronic density-of-states at Fermi level and the characteristic Debye temperature of lattice. These results reflect certain degrees of electron localization between aluminum and lithium atoms, providing a fundamental basis for solid solution strengthening in the lightweight materials with great potential in aerospace applications. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The dynamics of a toroidal bubble near a solid wall for a large part of stand-off parameters γ (γ = d/Rmax, d is the distance between the solid wall and the bubble centre at the moment of formation and Rmax is the maximum bubble radius) have been extensively studied, but some mechanics of a toroidal bubble are not completely clear, especially for the small stand-off parameters γ ≤ 0.8. In the present study, on the basis of the finite volume method, the Navier-Stokes equations with invis-cid and incompressible assumption are directly solved using a staggered grid on the fixed grid. The dynamics of the toroidal bubble near the solid for different stand-off parameters (γ = 0.4,0.6,0.8, and 0.97, respectively) are simulated by a front tracking method. Initial conditions of numerical simulation are estimated through the Rayleigh-Plesset equation, based on the maximum size and collapse time of a spark-generated bubble. One of the numerical results is compared with a spark-generated bubble experiment, showing that the results between them are favorable with regard to both the bubble shape history and translational motion of the bubble. The numerical results for the different stand-off parameters, including the change process of the water layer, the development process of the splash flow and radial flow, the splitting phenomenon of the toroidal bubble, and the trend of pressure on the center of the solid wall, are discussed, where some new phenomena are discovered. [ABSTRACT FROM AUTHOR]

Presents a study that investigated the variations of the electrical resistivity, the magnetization and the grain-boundary precipitates of a nickel-rich nickel-indium alloy system. Experimental procedure; Results and discussion.

Investigates the variations of the grain-boundary precipitates, the electrical resistivity and the magnetization of a Ni-8 at. tin alloy as functions of annealing temperature and annealing time. Preparation of the alloys; Microscope used to observe the grain-boundary precipitates; Information on the magnetization of the homogenized sample.

Presents a study on the influence of crystal structure on the magnetoresistance of cobalt (Co)/chromium (Cr) multilayers. Characteristics of epitaxial Co/Cr multilayers; Definition of the giant magnetoresistance in multilayers; Effects due to the spin dependent scattering at the interfacial regions of the superlattice.

Presents a study which examined the optical, electrical and magnetic properties of neodymium iron boron films. Experimental methods; Observations of the oscillatory behavior with thickness of the films; Anomalous behaviors near the Curie temperature.

Wave propagation can be manipulated at a deep subwavelength scale through the locally resonant metamaterial that possesses unusual effective material properties. Hyperlens due to metamaterial's anomalous anisotropy can lead to superior-resolution imaging. In this paper, a single-phase elastic metamaterial with strongly anisotropic effective mass density has been designed. The proposed metamaterial utilizes the independently adjustable locally resonant motions of the subwavelengthscale microstructures along the two principal directions. High anisotropy in the effective mass densities obtained by the numerical-based effective medium theory can be found and even have opposite signs. For practical applications, shunted piezoelectric elements are introduced into the microstructure to tailor the effective mass density in a broad frequency range. Finally, to validate the design, an elastic hyperlens made of the single-phase hyperbolic metamaterial is proposed with subwavelength longitudinal wave imaging illustrated numerically. The proposed single-phase hyperbolic metamaterial has many promising applications for high resolution damage imaging in nondestructive evaluation and structural health monitoring. [ABSTRACT FROM AUTHOR]

The ability to control elastic wave propagation at a deep subwavelength scale makes locally resonant elasticmetamaterials very relevant. A number of abilities have been demonstrated such as frequency filtering, wave guiding, and negative refraction. Unfortunately, few metamaterials develop into practical devices due to their lack of tunability for specific frequencies. With the help of multi-physics numerical modeling, experimental validation of an adaptive elasticmetamaterial integrated with shunted piezoelectric patches has been performed in a deep subwavelength scale. The tunable bandgap capacity, as high as 45%, is physically realized by using both hardening and softening shunted circuits. It is also demonstrated that the effective mass density of the metamaterial can be fully tailored by adjusting parameters of the shunted electric circuits. Finally, to illustrate a practical application, transient wave propagation tests of the adaptive metamaterial subjected to impact loads are conducted to validate their tunable wave mitigation abilities in real-time. [ABSTRACT FROM AUTHOR]

A wide variety of liquid and solid phase crystallized silicon films are investigated in order to determine the performance limiting defect types in crystalline silicon thin-film solar cells. Complementary characterization methods, such as electron spin resonance, photoluminescence, and electron microscopy, yield the densities of dangling bond defects and dislocations which are correlated with the electronic material quality in terms of solar cell open circuit voltage. The results indicate that the strongly differing performance of small-grained solid and large-grain liquid phase crystallized silicon can be explained by intra-grain defects like dislocations rather than grain boundary dangling bonds. A numerical model is developed containing both defect types, dislocations and dangling bonds, describing the experimental results. [ABSTRACT FROM AUTHOR]

Two high-k dielectric materials (Al2O3 and HfO2) were deposited on n-type (100) and (110) InAs surface orientations to investigate physical properties of the oxide/ semiconductor interfaces and the interface trap density (Dit). X-ray photoelectron spectroscopy analyses (XPS) for native oxides of (100) and (110) as-grown n-InAs epi wafers show an increase in As-oxide on the (100) surface and an increase in InOx on the (110) surface. In addition, XPS analyses of high-k (Al2O3 and HfO2) on n-InAs epi show that the intrinsic native oxide difference between (100) and (110) epi surfaces were eliminated by applying conventional in-situ pre-treatment (TriMethyAluminium (TMA)) before the high-k deposition. The capacitance-voltage (C-V) characterization of HfO2 and Al2O3 MOSCAPs on both types of n-InAs surfaces shows very similar C-V curves. The interface trap density (Dit) profiles show Dit minima of 6.1 × 1012/6.5 × 1012 and 6.6 × 1012/7.3 × 1012 cm-2 eV-1 for Al2O3 and HfO2, respectively for (100) and (110) InAs surfaces. The similar interface trap density (Dit) on (100) and (110) surface orientation were observed, which is beneficial to future InAs FinFET device with both (100) and (110) surface channel orientations present. [ABSTRACT FROM AUTHOR]

A length extensional mode lead zirconate titanate (PZT)-on-Si resonator is presented using 50 Ω termination with high-stopband rejection exploiting feed-through cancellation. A 250-nm-thick (100)-dominant oriented PZT thin-film deposited on top of 3 μm Si using pulsed laser deposition has been used. The resonator is presented with the length of 40 μm (half-wavelength), which corresponds to a resonance frequency of about 83 MHz. The effect of feed-through cancellation has been studied to obtain high-stopband rejection using bottom electrode patterning in the presence of a specific grounding resistance. Using this technique, the stopband rejection can be improved by more than 20 dB. [ABSTRACT FROM AUTHOR]

Transition metal oxide-based resistor random access memory (RRAM) takes advantage of oxygen-related defects in its principle of operation. Since the change in resistivity of the material is controlled by the oxygen deficiency level, it is of major importance to quantify the kinetics of the oxygen diffusion, key factor for oxide stoichiometry. Ab initio accelerated molecular dynamics techniques are employed to investigate the oxygen diffusivity in amorphous hafnia (HfOx, x = 1.97, 1.0, 0.5). The computed kinetics is in agreement with experimental measurements. [ABSTRACT FROM AUTHOR]

An interfacial monolayer of CuO in Cu-coated γ-Fe2O3 nanoparticles enables significantly decreased intrinsic surface spin disorder compared to bare γ-Fe2O3 nanoparticles. Element specific x-ray absorption spectroscopy at the L-edges for Cu and Fe indicates that the magnetic moment of the CuO in the shell interacts with the γ-Fe2O3 nanoparticle's surface magnetic moments. This exchange interaction cants the moments of the CuO resulting in a non-zero Cu moment, altering the γ-Fe2O3 nanomagnetism. [ABSTRACT FROM AUTHOR]

Impact of set/reset pulse duration and amplitude on the endurance failure modes of TiN\Ta2O5\Ta cells is investigated and is related to interaction between Oxygen and TiN bottom electrode during reset. Hourglass electrical switching simulation of conductive filament temperature during reset transient and ab-initio calculation of reaction energy further support this degradation mechanism. Based on this understanding, endurance improvement is achieved by using shorter reset pulse and/or using inert Ru bottom electrode. [ABSTRACT FROM AUTHOR]

It is shown by means of the Cronström gauge condition [Phys. Lett. B 90, 267 (1980)] and the constrained variational principle that there exist nonsymmetric solutions to the steady-state Ginzburg–Landau equations with arbitrary parameter λ>0 in bounded domain Ω contained in two-dimensional Euclidean space. [ABSTRACT FROM AUTHOR]

In this paper, the occurrence of a linearization phenomenon in the Abelian Higgs model for isotropic solutions will be proved. In this linearizing process, as the parameter λ→∞, the smooth solutions of the nonlinear differential equations will degenerate to the Green’s function of the related linearized equation, which is an inhomogeneous linear elliptic equation. [ABSTRACT FROM AUTHOR]

With Al2O3 passivation on the surface of Cu(In,Ga)Se2, the integrated photoluminescence intensity can achieve two orders of magnitude enhancement due to the reduction of surface recombination velocity. The photoluminescence intensity increases with increasing Al2O3 thickness from 5 nm to 50 nm. The capacitance-voltage measurement indicates negative fixed charges in the film. Based on the first principles calculations, the deposition of Al2O3 can only reduce about 35% of interface defect density as compared to the unpassivated Cu(In,Ga)Se2. Therefore, the passivation effect is mainly caused by field effect where the surface carrier concentration is reduced by Coulomb repulsion. [ABSTRACT FROM AUTHOR]

Electron barrier height measurements at TiNx/HfO2 interfaces in metal-insulator-metal structures using internal photoemission of electrons reveal a significant (≈1 eV, i.e., about 1/3 of the total barrier height) influence of the opposite electrode material, i.e., Hf versus TiNx. This effect is suggested to be caused by oxygen scavenging from HfO2 by the opposite Hf electrode resulting in generation of positive charges in the oxide above the metal electrode surfaces. Such a considerable interface dipole component demonstrates a principle that may be used to tune the barrier. [ABSTRACT FROM AUTHOR]

By high temperature microscopy, we conducted in-situ observation on the evolution of peritectic melting of YBa2Cu3O7-y thin films (denoted as the α phase). As the α phase was highly superheated above a critical temperature, we found that a non-equilibrium phase transition occurred. An unexpected metastable Y2O3 phase (denoted as the γ phase), resulted from the decomposition of the α film, nucleated preferentially to the stable phase of Y2BaCuO5 (denoted as the β phase). Both high superheating capability of the α film and low interface energy of the γ phase with substrates are responsible for the metastable phase transition in this work. [ABSTRACT FROM AUTHOR]

In this letter, we study the influence of the Pt top-electrode thickness and of the chamber atmosphere during cell operation on the resistive switching of TiN\HfO2\Pt cells. The oxygen permeability of the Pt electrode directly in contact with the atmosphere significantly affects the resistive switching and the resistance states of the cell. The results provide strong experimental indications that the electroforming operation leads to oxygen-vacancy formation and that the subsequent reset operation relies on the available oxygen species in the filament neighborhood. Significant implications with respect to endurance and retention assessment of resistive-switching memory devices are discussed. [ABSTRACT FROM AUTHOR]

A flexible Ge-on-polyimide photodetector is demonstrated. The single crystalline thin film of Ge was transferred on the polyimide by adhesive wafer bonding and smart-cut techniques. A simple tunneling metal-oxide-semiconductor structure is fabricated for the detector applications. Due to the transparency of the polyimide, the responsivity of the detector is sensitive to the environments. At -2 V, the photodetector on the stainless steel has responsivities of 220, 200, and 140 mA/W at wavelength of 850, 1310, and 1550 nm, respectively. [ABSTRACT FROM AUTHOR]

Si-based photodetectors for narrow-band ultraviolet light (319 nm) and green light (500 nm) detection are demonstrated using a metal-oxide-semiconductor tunneling structure. By using appropriate selection of gate metal, the metal-oxide-semiconductor tunneling diode can detect specific range of light. Due to the spectral dependence of absorption and reflection of the Ag and Au as gate electrodes, the narrow-band detection of ultraviolet and green light can be achieved, respectively. The photodetectors with 130 nm thick Ag gate and 70 nm thick Au gate exhibit peak responsivities of 5.1 and 0.3 mA/W at 319 and 500 nm, respectively. [ABSTRACT FROM AUTHOR]

The thermal conductivity and electrical resistivity of a suspended nickel nanowire have been measured for T=15–300 K. The temperature dependence of the thermal conductivity and the Lorenz number strongly differ from the bulk. The comparison of the transports in the Ni nanowire shows, that at temperatures 75

Iron disilicide in a bulk form is practically nonmagnetic. In contrast, nanoparticles of FeSi2 exhibit superparamagnetism with blocking temperatures ranging from 8 K (15 nm) to 34 K (55 nm). Their relatively low saturation magnetization suggests that the magnetic behavior is associated with only a small fraction of Fe ions, which have a sufficient number of other Fe as nearest neighbors. The chemical disorder is presumably induced in the formation of nanoparticles. A spin glass-type anomaly below 10 K observed in specific heat data gives a further evidence for the compositional heterogeneity. [ABSTRACT FROM AUTHOR]

Single crystals of Sr2HoRu1-xCuxO6 (with x=0–0.2), measuring 2–3 mm across have been grown from PbO–PbF2 based solutions in the temperature range of 1250–1150 °C. The crystals exhibit octahedral morphology and belong to the monoclinic space group P21/n. While Sr2HoRuO6 is found to be antiferromagnetic with weak ferromagnetism below 30 K, the solid solutions containing Cu exhibit a diamagnetic transition at 31 K which increases in magnitude and temperature with increasing Cu. Through a correlation of magnetic and calorimetric properties, these crystals are concluded to be spin-glass superconductors. [ABSTRACT FROM AUTHOR]

The tensile properties and fatigue lives of a bulk Cu0.5NiAlCoCrFeSi glassy alloy were measured in 288 °C water and compared with those obtained in air at ∼25 °C. The bulk glassy alloy retained good tensile properties in 288 °C water, i.e., tensile fracture strength and tensile fracture elongation were, respectively, 2660 MPa and 2.01% in air and a little lower, 2000 MPa and 1.49%, in 288 °C water. The results of fatigue tests confirmed the significant decrease in fatigue life in high-temperature water. A decrease in strain rate from 0.5 to 0.001% s-1 decreased fatigue life by a factor of ∼5. [ABSTRACT FROM AUTHOR]

Evidence of elemental copper magnetism in Cu-coated γ-Fe2O3 nanoparticles was revealed by element specific x-ray absorption spectroscopy and magnetic circular dichroism (XMCD). An interfacial layer of magnetic CuO was discovered that interacted with the Fe3+ surface magnetic moments. This unexpected exchange interaction canted the moments of the CuO, so that a non-zero net magnetic moment was measured. XMCD measurements as a function of field on the copper coated γ-Fe2O3 nanoparticles indicated that the CuO magnetic moment was aligned with the octahedral Fe3+ and its magnetization was modified by the changing applied field. With increasing copper thickness, a stronger field dependence of the Fe3+ and Cu2+ magnetization was observed. [ABSTRACT FROM AUTHOR]

Ab initio density functional calculations, transmission electron microscope, and x-ray diffraction (XRD) were used to study the dominant factor of increased coercivity for the doping effect in SmCo7-xZrx (x = 0 to 0.3). Simulated values of saturated magnetization are 940 emu/cm3 for SmCo7 and 799 emu/cm3 for SmCo6.7Zr0.3, which agree with experimental results within 6%. The calculated anisotropy constant (for 2e) increases from 1.151 × 107 erg/cm3 for SmCo7 to 1.934 × 107 erg/cm3 for SmCo6.7Zr0.3. The grain sizes remain almost the same by adding ∼4% (atomic percent) Zr through the analyses of XRD. The increased anisotropy is the dominated factor for enhancing the coercivity in SmCo6.7Zr0.3. In addition, both results of Rietveld refinements of XRD data and ab initio calculations show that Zr situating at 2e/3g positions are more stable than 2e/2e locations, which were suggested conventionally. [ABSTRACT FROM AUTHOR]

The microstructure, ordering parameter, and magnetic properties of multilayer [FePt(x)/Os]n films on glass substrate by dc-magnetron sputtering (with x being thickness in nm; Os with a fixed thickness 5 nm; n being the number of layers) have been studied as a function of the annealing temperatures between 300 and 900 °C. The grain size of multilayer films can be controlled by annealing temperature and thickness of the FePt layer with Os space layer. The coercivity as a function of the annealing temperature for samples with n = 1 and pure FePt behaves roughly saturated after annealing above 700 °C. However, for samples with n > 4 the value of Hc seems still increasing with increasing annealing temperature between 600 and 900 °C, and the ordering parameter decreases with increasing the number of Os layers. Our experimental results are reasonably well to describe the effect of strain-assisted transformation. [ABSTRACT FROM AUTHOR]

Angle-dependent x-ray absorption near edge structure (XANES) and scanning photoelectron microscopy (SPEM) measurements have been performed to differentiate local electronic structures of the tips and sidewalls of highly aligned carbon nanotubes. The intensities of both &pi*- and σ*-band C K-edge XANES features are found to be significantly enhanced at the tip. SPEM results also show that the tips have a larger density of states and a higher C 1s binding energy than those of sidewalls. The increase of the tip XANES and SPEM intensities are quite uniform over an energy range wider than 10 eV in contrast to earlier finding that the enhancement is only near the Fermi level. [ABSTRACT FROM AUTHOR]

As-grown and Zn-implanted wurtzite GaN samples have been studied by angle-dependent x-ray absorption near edge structure (XANES) measurements at the N and Ga K-edges and the Ga L[SUB3]-edge. The angle dependence of the XANES spectra shows that the Ga-N bonds lying in the bilayer have lower energies than bonds along the c-axis, which can be attributed to the polar nature of the GaN film. The comparison of the Ga L[SUB3]-edge XANES spectra of as-grown and Zn-doped GaN reveals significant dopant induced enhancement of near-edge Ga d-derived states. [ABSTRACT FROM AUTHOR]

X-ray-absorption near edge structure (XANES) measurements have been performed to investigate the local electronic structures of the Fe-catalyzed and stabilized carbon nanotubes (CNT) with various diameters. The intensities of the π[sup *]- and σ[sup *]-band and the interlayer-state features in the C K-edge XANES spectra of these CNTs vary with the diameter of the CNT. The white-line features at the C K- and Fe L[sub 3]-edges suggest a strong hybridization between the C 2p and Fe 3d orbitals, which lead to an enhancement of the C K- and reduction of the Fe L[sub 3]-edge features, respectively, indicative of a charge transfer from C 2p to Fe 3d orbitals. The Fe K-edge spectra reveal a p–d rehybridization effect that reduces p-orbital occupation at the Fe site. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

X-ray absorption near edge structure (XANES) spectra of hard amorphous a-Si–C–N thin films with various compositions were measured at the C and N K-edge using sample drain current and fluorescent modes. The C K-edge XANES spectra of a-Si–C–N contain a relatively large 1s→π[sup *] peak, indicating that a substantial percentage of carbon atoms in the a-Si–C–N films have sp[sup 2] or graphite-like bonding. Both the observed sp[sup 2] intensity and the Young’s modulus decrease with an increase in the carbon content. For N K-edge XANES spectra of the a-Si–C–N films we find the emergence of a sharp peak near the threshold when the carbon content is larger than between 9% and 36%, which indicates that carbon and nitrogen atoms tend to form local graphitic carbon nitride. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

X-ray absorption spectroscopy has been used to investigate the electronic structure of as-deposited and oxidized Ni/Au contacts on p-GaN. The Ni K-, L[sub 2,3]-, and O K-edges x-ray absorption spectra clearly show the formation of NiO in the annealed contacts. Annealing in air increases Ni-site hole concentration and slightly shortens the nearest-neighbor Ni-O bond length, which enhances p-d hybridization and charge transfer from Ni to O. The observed very low specific contact resistance in the oxidized contacts is found to be due to the enhanced hole concentration at the Ni site. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

X-ray absorption near-edge structure (XANES) measurements have been performed for nitrogen (N) containing diamond films with three different N concentrations at the C K-edge using the sample drain current mode. The C K-edge XANES spectra of these diamond films resemble that of the pure diamond regardless of the N concentration, which suggests that the overall bonding configuration of the C atom is unaltered. N impurities are found to reduce the intensities of both the sp[sup 2]- and sp[sup 3]-bond derived resonance features in the XANES spectra. The valence-band photoelectron spectra indicate that N atoms cause the broadening of the valence band σ- and π-bond features and the enhancement and reduction of the σ- and π-bond features, respectively. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]