bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aerosol Deposition Method (Adm) For Nano-Crystal Ceramics Coating Without Firing
Authors: Akedo Jun , Lebedev Maxim , Iwata Atsushi , Ogiso Hisato , Nakano Shizuka 
Published: June 2019

AbstractAerosol deposition method (ADM) for shock-consolidation of fine ceramics powder to form dense and hard layers is reported. Submicron ceramic particles were accelerated by gas flow in the nozzle up to velocity of several hundred m/s. During interaction with substrate, these particles formed thick (10 ∼ 100 μm), dense, uniform and hard ceramics layers. Experiments were fulfilled at room temperature. The results of fabrications, microstructure and mechanical properties of oxides (Al2O3; (Ni,Zn)Fe2O3; Pb(Zr0.52,Ti0.48)O3 and non-oxide (AlN; MgB2) materials are presented. Every layer has polycrystalline structure with nano-meter order scale.
Using Fluctuations To Locate The Surface Roughening Transition
Authors: Bentz Daniel N. , Jackson Kenneth A. 
Published: June 2019

AbstractAn analysis of the fluctuations of a {100} FCC interface has been used to locate the surface roughening transition in kinetic Monte Carlo simulations. These simulations were conducted using a spin 1/2 Ising model treatment of the solid-liquid interface. A temperature gradient was imposed on the simulation cell providing a restoring force to the interface. Fluctuations in the number of solid atoms in the system were measured using time correlations. The fluctuation dissipation theorem was employed to relate the characteristic times retrieved from the time correlation to the kinetic coeffcients of the system. A dramatic change was found in these characteristic times, which locates the surface roughening transition.
Structural Evolution and Acoustic Phonon Behavior in Crystalline PTFE Latex Films
Authors: Pierno M. , Casari C.S. , Bassi A. Li , Beghi M.G. , Piazza R. , Bottani C.E. 
Published: June 2019

AbstractThe structural evolution of polytetrafluoroethylene (PTFE) crystalline polymer latex films is studied at hundreds nanometer length scale by atomic force microscopy and Brillouin light scattering. In a controlled sintering process the transition is observed from the original particle distribution towards a ‘fibrillar’ structure of crystalline regions embedded in a disordered matrix. This transition is accompanied by a cross-over from localized acoustic excitations to propagating acoustic phonons, related to mesoscopic elastic properties. After sintering, a ‘mark’ of the original particulate structure persists, suggesting that filming of crystalline polymers may be analogous to sintering of ceramic powders. Films of crystalline polymers can thus be exploited as model systems to study the elasto-optical properties of granular and disordered media.
Geometrical Contribution to Yield Strength in Small Volumes
Authors: Dunstan D.J. , Bushby A.J. 
Published: June 2019

AbstractCritical thickness theory was developed to account for the ability of thin epitaxial metal and semiconductor layers to support high misfit or coherency strain. The thermodynamic equilibrium theory is correct, and is well approximated by a theory based on geometrical arguments. The latter theory is readily extended to arbitrary misfit strain profiles including linearly graded layers, for which a surface layer free of misfit dislocations. This result applies as well to linear strain gradients introduced by deformation, in which case the misfit dislocations are known as geometrically necessary dislocations. We show that a consequence of this surface layer is that the apparent yield strength of the material increases in small structures such as thin wires in torsion. Under large plastic deformation, even if the material is perfectly plastic, critical thickness theory also predicts an apparent work-hardening. The predictions of critical thickness theory are in excellent agreement with experimental data in the literature.
Multiscale Modeling of Mechanical Response of Quantum Nanostructures
Authors: Tewary Vinod K. , Yang Bo 
Published: June 2019

AbstractA multiscale Green's function method is described for modeling the mechanical response of quantum nanostructures in semiconductors. The method accounts for the discreteness of the lattice in and around the nanostructure, and uses the continuum Green's function to model extended defects such as free surfaces in the host solid. The method is applied to calculate the displacement field due to a Ge quantum dot in a semi-infinite Si lattice. Corresponding continuum values of the displacement field are also reported.
Dislocation Behavior During Deformation- Combining Experiments, Simulation and Modeling.
Authors: Robertson I.M. , Robach J. , Wirth B. , Arsenlis A. , Livermore Lawrence 
Published: June 2019

AbstractIn situ straining in the transmission electron microscope has been combined with molecular dynamics computer simulations to investigate the nature of the interaction of glissile dislocations with radiation-produced defects (loops, stacking-fault tetrahedra, and He bubbles), and to determine the mechanisms by which the dislocation loops and stacking-fault tetrahedra are annihilated and defect-free channels are created. The defect pinning strength depends on the defect and on the interaction geometry. The experiments and simulations show that a single interaction is not always sufficient to annihilate a dislocation loop or a stacking-fault tetrahedra and that the nature of the defect may be changed because of the interaction. The edge/screw character of the dislocation is also important as they have different efficiencies for annihilating a defect. The dislocations responsible for creating the defect-free channels are not the preexisting dislocations but originate from grain boundaries and other stress concentrators. Cross-slip of dislocations within the channels is important for clearing and widening the channel and can create new channels. Based on these observations a dispersed-barrier hardening model in which the influence of the radiation defects and dislocation density are combined. The resulting model predicts the observed behavior, including the apparent yield drop at high defect densities.
Inhomogeneous Distribution of Dislocation Density as Manifestation of Multiscale Structure in Tubes from Zr - Based Alloys
Authors: Perlovich Yuriy , Isaenkova Margarita 
Published: June 2019

AbstractAn X-ray method was developed to determine the dislocation density in metal materials as a distribution depending on the orientation of Burgers vector. The method includes registration of X-ray line profiles by each successive position of the sample in the course of diffractometric texture measurement using reflections of two orders, the following determination of coherent domain size and lattice distortion by means of the Warren-Averbach method for each orientation of reflecting planes, separate calculation of the density of c- and a-dislocations with all possible orientations of Burgers vector and presentation of results in the generalized pole figures. The method was used to determine the dislocation density in tubes of Zr-based alloys for nuclear industry. Obtained data show, that the dislocation density varies within very wide interval of several orders of magnitude depending on the grain orientation both in as-rolled and annealed tubes. Features of the dislocation distribution in tubes are closely related to their crystallographic texture.
Some Theoretical Aspects of the Grüneisen Coefficient for the Equation of State of Solids
Authors: Chaissé Francis , Heuzé Olivier 
Published: June 2019

AbstractThe aim of this study is to specify the Güneisen coefficient variation versus volume γ(V). First for isotropic solid, and in the anharmonic approximation we recall the various classical laws on γ(V). On the other hand, the shock wave physics have shown the experimental evidence of the linear relationship between shock velocity (U) versus jump of particle velocity (u) with some further consequences on γ(V) [cf. MRS Symp. Proc. vol 731 paper W-8.1 (Spring 2002)]. In this paper, we point out the failure of the γ(V) representation in the anharmonic approximation to reproduce the shock wave data U(u). Taking now into account the anharmonic effects in solids, we propound a new analysis of the γ(V) law which is well suited for the shock wave physics of solids.
Microdiffraction Experiments and Modeling for Analyzing Multiscale Dislocation Ensembles in Materials
Authors: Ice G.E. , Barabash R.I. , Pang J. 
Published: June 2019

AbstractThe intensity distribution of Laue diffraction is analyzed as a function of local misorientation. We show how unpaired dislocations alter the white beam Laue patterns for isolated dislocations, for dislocation walls, and for a combination of both. We consider the effect of different statistically and geometrically necessary dislocation densities on the intensity distribution along and perpendicular to the Laue streak. A 3D x-ray crystal microscope is used to analyze the complicated plastic-elastic field in a grain of a Ni polycrystalline sample during in-situ uniaxial pulling. A change of dislocation activity with depth is demonstrated. The dislocation slip systems and their densities are determined at various depths. The model parameters are used to simulate the whole Laue pattern including details about the contours for specific Laue spots; good agreement is found between simulated and experimental contours.
Electrochemistry of Tin in Borate Buffer Solutions: An in-situ Raman study.
Authors: Díaz Raül , Díez-Pérez Ismael , Grostiza Pau , Sanz Fausto , Joiret Susanne , Allongue Philippe 
Published: June 2019

AbstractThe electrochemical behavior of chemically polished polycrystalline tin is investigated in borate buffer solutions at pH=7.5 using in-situ Raman measurements. Experiments reveal the appearance of “luminescence” under continuum red laser light only for a narrow range of sample potentials within the anodic plateau. The phenomenon is discussed in view of the tin oxides formed on the surface, and correlated with the assignation of the oxido-reduction processes observed in the voltammograms.
Effect of Low Temperature Annealing on High Field Magnetoresistance and Hall effect in (Ga, Mn)As Dilute Magnetic Semiconductors
Authors: Ghosh K. , Arif Mohammad , Kehl T. , Patel R. J. , Mishra S. R. , Broerman J. G. 
Published: June 2019

ABSTRACTIn this paper we report the effect of low temperature annealing on the high field magnetotransport properties of epitaxial thin films of (Ga, Mn)As Dilute Magnetic Semiconductor (DMS) with low concentration (1.5 %) of Mn doping, which results in a ferromagnetic insulator. Annealing at an optimal temperature enhances the conductivity, carrier concentration, and ferromagnetic transition temperature. The field dependence of magnetoresistance is different below and above the ferromagnetic transition temperature. An attempt is made to analyze the data using a theoretical model proposed by Kaminski and Das Sarma [1].
UV Raman Scattering Analysis of Indented and Machined 6H-SiC and β-Si3N4 Surfaces
Authors: Walter Jennifer J.H. , Liang Mengning , Chen Xiang-Bai , Jang Jae-il , Bergman Leah , Patten John A. , Pharr George M. , Nemanich Robert J. 
Published: June 2019

ABSTRACTUV Raman scattering is employed as a nondestructive structure sensitive probe to investigate the vibrational properties of the wide bandgap, machined and indented surfaces of 6H-SiC and β-Si3N4. In these materials, the short absorption depth of UV light allows for accurate probing of the surface, and the transparency to visible light allows for analysis of the bulk material. The study on 6H-SiC (0001) included measurements of indentations, and of machined circular (0001) wafer edges. The indentation analysis indicates the response of the material to localized pressures. Machined 6H-SiC wafer edges and machined β-Si3N4 surfaces indicate a ductile response and ductile material removal for machining at cutting depths on a nm and μm scale. Raman scattering measurements of the ductile surfaces and ductile material removed indicate residual structure changes. The residual surface structures could indicate that a high-pressure phase transformation is the origin of a ductile response on machined brittle materials.
Highly and Rapidly Stabilized Protocrystalline Silicon Multilayer Solar Cells
Authors: Lim Koeng Su , Kwak Joong Hwan , Kwon Seong Won , Myong Seung Yeop 
Published: June 2019

AbstractWe have developed highly stabilized (p-i-n)-type protocrystalline silicon (pc-Si:H) multilayer solar cells. However, the source of the superior light-induced stability of the pc-Si:H multilayer absorbers compared to conventional amorphous silicon (a-Si:H) absorbers remains unclear. Photoluminescence (PL) and Fourier transform infrared (FTIR) spectroscopy measured at room temperature produce strong evidence that nano-sized silicon grains embedded in regularly arranged highly H2-diluted sublayers suppress the photocreation of dangling bonds. To achieve a high conversion efficiency, we applied a double-layer p-type amorphous siliconcarbon alloy (p-a-Si1-xCx:H) structure to the pc-Si:H multilayer solar cells. The less pronounced initial short wavelength quantum efficiency variation as a function of bias voltage, and the wide overlap of dark current - voltage (JD-V) and short-circuit current - open-circuit voltage (Jsc-Voc) characteristics prove that the double p-a-Si1-xCx:H layer structure successfully reduces recombination at the p/i interface. Thus, we achieved a highly stabilized efficiency of 9.0 % without any back reflector.
Multiple-Trapping Model with Meyer-Neldel Effect and Field-Dependent Effects: Time-Of-Flight Simulations for a-Si:H
Authors: Maassen Jesse , Yelon Arthur , Hamel Louis-André , Chen Wen Chao 
Published: June 2019

AbstractWe have included both the Meyer-Neldel rule and field assisted detrapping in the multiple-trapping model, assuming exponential band tails of localized states. Monte Carlo simulations with fixed parameters provide transient currents and comparison of calculated and measured mobility, μ(T,F), and pre-transit dispersion parameter, α1(T,F), which are presented for temperatures ranging from 25 K to 333 K and fields from 20 kV/cm to 400 kV/cm. We observe that the values of μ1(T,F) and α(T,F) are improved with this combined model. Although this model provides satisfactory results for carrier transport for all temperature and field, differences in experimental data causes deviation of simulated results from experiment.
AFM Morphology Study of Si1-Y GeY:H Films Deposited by LF PE CVD from Silane-Germane with Different Dilution
Authors: Sanchez L. , Kosarev A. , Torres A. , Felter T. , Ilinskij A. 
Published: June 2019

AbstractThe morphology of Si1-Y GeY:H films in the range of Y=0.23 to 0.9 has been studied by AFM. The films were deposited by Low Frequency (LF) PE CVD at substrate temperature Ts=300 C and discharge frequency f=110 kHz from silane+germane mixture with and without, Ar and H2 dilution. The films were deposited on silicon and glass substrates. AFM images were taken and analyzed for 2x2 μm2 area. All the images demonstrated “grain” like structure, which was characterized by the height distribution function F(H) average roughness <H>, standard height deviation Rq, lateral correlation length Lc, area distribution function F(s), mean grain area 
, diameter distribution function F(d), and mean grain diameter <d>. The roughness <H> of the films monotonically increases with Y for all dilutions, but more significantly in the films deposited without dilution. Lc continuously grows with Y in the films deposited without dilution, while more complex behavior of Lc(Y) is observed in the films deposited with H- or Ar dilution. The sharpness of F(H) characterized by curtosis γ depends on dilution, and the sharpest F(H) are for the films deposited with Ar ( γ=5.30,Y=0.23) and without dilution (γ=4.3, Y=0.45). Isothermal annealing caused an increase of <H>, Lc in the films deposited with H- and Ar dilutions, while in the films prepared without dilution the behavior was more complex, depending on the substrates. After the annealing a significant sharpening of the height distributions, F(H), was observed in the films deposited with H dilution or without dilution.
Optical Properties of Amorphous Silicon-Yttrium Films
Authors: N. Shmyryeva Alexandra , V. Semikina Tetyana 
Published: June 2019

AbstractThis paper presents and discusses the results of measuring IR reflection and ellipsometric parameters, optical microscopy and AFM the mixed phase of amorphous Si:Y films with microcrystalline inclusions. These films were obtained by electron-beam evaporation of siliconyttrium alloys with different Y concentration (5-30 %) at two substrate temperatures (370 and 620 °C).
Fabrication of Nano-Crystalline Porous Silicon on Si Substrates by a Plasma Enhanced Hydrogenation Technique
Authors: Abdi Y. , Hashemi P. , Karbassian F. , Nayeri F.D. , Behnam A. , Mohajerzadeh S. , Koohsorhki J. , Robertson M.D. , Arzi E. 
Published: June 2019

AbstractA novel plasma hydrogenation method for the fabrication of nano-crystalline structures of silicon as well as the photoluminescence and structural properties of these porous structures is presented. We have observed that the hydrogenation process followed by an annealing treatment results in the formation of nano-crystalline silicon structures where increased temperatures during hydrogenation reduces the grain size. Furthermore, by increasing the time of the hydrogenation process, the density of the silicon grains is increased.Photoluminescence (PL) spectroscopy demonstrated the presence of a direct gap in the visible light range where materials with a smaller grain size emitted light at lower wavelengths, and a higher density of grains resulted in higher amplitudes in the PL spectrum. TEM and SEM characterization of these samples and the structure-emission relationship are also presented.
Nanocrystalline Si Films and Devices Produced Using Chemical Annealing with Helium
Authors: Wang Nanlin , Dalal Vikram L. 
Published: June 2019

AbstractWe report on growth of nanocrystalline Si:H films and devices using a layer-by-layer growth technique, where the growth of a thin amorphous layer by PECVD is followed by chemical annealing in a Helium plasma. The films and devices were grown using a remote, low pressure ECR plasma process. It was found that the structure of the films grown using the layerby-layer technique depended critically upon whether the annealing was done with hydrogen or helium, and the time taken to do the annealing. When the annealing was done in a hydrogen plasma, the films remained amorphous; in contrast, when the annealing was done in helium, and the annealing time was increased to 20 seconds from 10 seconds, the films became crystalline. The crystallinity of the films was confirmed using Raman spectroscopy and x-ray diffraction. The result obtained here shows that it is not necessary to have a high hydrogen dilution to obtain nanocrystalline films. Rather, the amount of hydrogen already present in an amorphous film is enough to cause crystallization, provided that enough ion flux and perhaps energy are available for converting the amorphous structure to a crystalline structure. Proof - of - concept p+nn+ junction devices were fabricated in these chemically annealed materials, and they showed classical nanocrystalline Si solar cell type behavior.
Ultra-Shallow Junction Formation by a Non-Melting Process; Double-Pulsed Green Laser Annealing
Authors: Kudo Toshio , Sakuragi Susumu , Yamazaki Kazunori 
Published: June 2019

AbstractIn order to investigate the possibility of nanosecond activation in the non-melting state, we adopted the method of double-pulsed green laser annealing (DPSS), controlling effectively the combined pulse width with two pulsed lasers (pulse duration: ˜100ns, frequency: 1kHz). We investigated the formation of ultra-shallow junctions (USJ) less than 10nm in spite of the deep penetration depth of the green wavelength in crystalline Si (˜1000nm). In order to limit the depth of B implant, a Ge pre-amorphization implant was performed at an energy of 3keV to a dose of 3E+14/cm2. After the pre-amorphization implant, a B implant was performed at 0.2kev and doses of 5E+14/cm2 and 1E+15/cm2. The implanted B dopants remain within the pre-amorphized Si layer. The double-pulsed laser irradiation was performed with a homogenized line beam of 0.1mm x 17mm, scanning a sample stage at a constant velocity of 10mm/s, that is, at an overlap ratio of 90%. The non-melting state was found to be in the pulse energy density range of E ≤ 780mJ/cm2 at a delay time of 300ns. Overcoming the issues of the short annealing time (˜<1μs) and the deep penetration depth (˜1000nm), we succeeded in the ultra-shallow junction formation beyond the 45nm CMOS node: maximum junction depth of 6nm, minimum sheet resistance of 0.65kohm/sq at a B dose of 1E+15/cm2, an abruptness of 1.4nm/dec.
Low Temperature Metal-Free Fabrication of polycrystalline Si and Ge TFTs by PECVD Hydrogenation
Authors: Hashemi Pouya , Derakhshandeh Jaber , Hekmatshoar Bahman , Mohajerzadeh Shamsoddin , Abdi Yaser , Robertson Michael D. 
Published: June 2019

AbstractPoly-crystalline Si and Ge layers were grown at low temperatures on glass substrates by successive hydrogenation and annealing steps, with no need to any metal incorporation. Hydrogenation is performed in an RF-PECVD apparatus with different powers of hydrogen plasma and the annealing step is carried out in the same system in N2 ambient. This leads to formation of granular Si and Ge structures with average grain size of less than 100nm at temperatures as low as 250°C and 150°C, respectively. The effect of hydrogen plasma power at various temperatures on the crystallinity of the layers has been studied by SEM and TEM analyzes. Successive hydrogenation and annealing at respective temperatures of 150°C and 200°C for Ge layer and 300°C for Si layer would result in a device-quality polycrystalline Ge and Si layers which have been employed for fabrication of thin-film transistors. These TFTs show the mobility of 80cm2/Vs and 4cm2/Vs and ON/OFF ratio of more than 103 and 5×104 for Ge and Si, indicating the feasibility of this technique for applications in large-area electronics.
Active Pixel TFT Arrays for Digital Fluoroscopy in a-Si:H Technology
Authors: Lai Jackson , Safavian Nader , Nathan Arokia , Rowlands John A. 
Published: June 2019

AbstractMajor development challenges in application of hydrogenated amorphous silicon (a-Si:H) technology to large area digital X-ray imaging and technological attributes such as low temperature deposition and high uniformity over large area evolve around dynamic imaging modalities such as fluoroscopy, which demands both high speed readout and signal amplification capabilities in addition to long term device stability. This work reports on initial results of a variety of TFT active pixel sensor (APS) structures in a-Si:H technology, each demonstrating unique capabilities such as enhancements in signal gain, TFT threshold voltage immunity, and real-time high speed readout.