bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microstructure and Modelling of RPV Embrittlement
Authors: English C. A. , Phythian W. J. , McElroy R-J. 
Published: April 2011

AbstractIn this paper we review the advances in understanding ofmicrostructural evolution during irradiation in pressure vessel steels. A particular focus is the benefits that arise from combining microstructural techniques on characterising the microstructure, especially the copper clusters. In addition to experimental techniques the importance of developing microstructurally based models linking the microstructural features to mechanical properties behaviour will be demonstrated. This paper will consider the recent advances in understanding in this area, and highlight the potential benefits that can be gained from a thorough understanding of the materials response to irradiation.
Clustering of Point Defects Under Electron Irradiation in Dilute Iron Alloys and an Iron Manganese Nickel Alloy
Authors: Hardouin-Duparc A. , Barbu A. 
Published: April 2011

AbstractIn low copper steels for nuclear reactor pressure vessel, point defect clustering seems to play an important role in hardening. In order to study the hardening component which results from the clustering of freely migrating point defects, we irradiated, in a high voltage electron microscope, Fe, the alloys Fe0.13%Cu and Fe0.014%P, alloys and the alloy Fel.5%Mn0.8%Ni0.1%Cu0.01%P, the composition of which is close to the matrix of pressure vessel steels. We studied the nucleation of dislocation loops and their growth velocity. We find out that copper and phosphorus have no effect on the vacancy migration energy but that this parameter decreased significantly in the complex alloy. The main point is certainly that loops are nucleated in the complex model alloy up to 500°C while no loop appears above 300°C in Fe and in FeCu. FeP shows an intermediate behavior.
Influence of the Irradiation Temperature on the Formation of Defects in Reactor Pressure Vessel Steels
Authors: Große M. , Hempel A. , Böhmert J. , Brauer G. , Haggag F. M. 
Published: April 2011

AbstractTwo heats of reactor pressure vessel steel type A533-B-1 differing in their Cu content (0.07 and 0.14 wt.-%) were irradiated to a fluence of 1* 1018 neutrons/cm2 at temperatures of 60, 121, and 288 °C, respectively. Their microstructure has been studied by SANS, SAXS, and PAS in the asirradiated and post-irradiation annealed stages and compared to the behaviour of unirradiated material and the results are discussed.
Dose Dependence of Radiation Induced Segregation in Proton Irradiated Austen1tic Alloys
Authors: Busby J. T. , Allen T. R. , Carter R. D. , Kenik E. A. , Was G. S. 
Published: April 2011

AbstractThe dose dependence of radiation-induced segregation (RIS) is investigated for proton irradiated ultra high-purity (UHP) 304L stainless steel and Fe-20Cr-24Ni. Grain boundary compositions were measured in samples irradiated with 3.2 MeV protons at 400°C to doses ranging from 0.1 to 3.0 dpa. RIS measurements were made using scanning transmission electron microscopy with energy dispersive x-ray spectroscopy (STEM/EDS) and compared to results from Auger electron spectroscopy (AES). Comparison of the dose dependence for HP-304L and Fe- 20Cr-24Ni shows that RIS is alloy specific. The approach to steady-state Cr depletion was observed to be more rapid in the alloy with higher Ni content. Fe-2OCr-24Ni reaches a steady-state Cr depletion level by 0.5 dpa, and the amount of Cr depletion in HP-304L SS is still increasing between 1.0 and 3.0 dpa. RIS in the stainless steel alloys irradiated with 3.2 MeV protons is comparable to that in neutron irradiated steels of similar composition.
Amorphization of Ceramic Materials by Ion-Beam-Irradiation: Parallels to Glass Formation
Authors: Wang L. M. , Wang S. X. , Gong W. L. , Ewing R. C. 
Published: April 2011

AbstractIon-beam-induced amorphization of a wide variety of ceramic materials has been investigated using in situ TEM at the HVEM-Tandem Facility at Argonne National Laboratory with 1.5 MeV Kr+ or Xe+ ions at temperatures between 20 to 1000 K. The critical amorphization temperatures and the activation energies associated with the expitaxial recovery of displacement cascades during irradiation have been determined from the temperature dependence of the critical amorphization dose. The results for phases in the A12 O3-MgO-SiO2 system suggested a parallel in the kinetics between ion-beam-induced amorphization and glass formation. Based on a cascade quenching model, a semiempirical parameter, S, which can easily be calculated from both structural and chemical parameters of a material, has been developed to predict the susceptibility of ceramics to amorphization. The critical amorphization temperature, above which irradiationinduced amorphization cannot be completed, is closely related to the glass transition temperature. The ratio between glass transition and melting temperatures can also be used to predict the susceptibility of a ceramic material to amorphization, equivalent to the Debye temperature criterion.
Nondestructive Optical Characterization of Radiationhardened Polyimide Films
Authors: Logan Randy , Maznev A. A. , Nelson Keith A. , Megusar J. 
Published: April 2011

AbstractA noncontact, nondestructive method is used to determine viscoelastic and thermal transport properties of a DuPont Kapton film before and after neutron irradiation to determine the changes that would be expected to occur in a nuclear reactor environment. The results demonstrate general capabilities for non-destructive evaluation (NDE) of radiation-induced material degradation. The specific application demonstrated is evaluation of insulation materials to be used in a superconducting magnet design in the International Thermonuclear Experimental Reactor (ITER).
Defects and Phase Change Induced by Giant Electronic Excitations With GeV Ions And 30MeV Cluster Beam
Authors: Thevenard P. , Beranger M. , Canut B. , Ramos S. M. M. , Bonardi N. , Fuchs G. 
Published: April 2011

AbstractMgO and LiNbO 3 single crystals were bombarded with GeV swift heavy ions (Pb, Gd) and 30MeV C60 clusters to study the damage production induced by giant electronic processes at stopping power up to 100keV/nm. The defect creation was characterized by optical absorption, transmission electron microscopy (TEM) and Rutherford backscattering spectrometry in channeling geometry (RBS-C). In MgO point defects (F type centers) and extended defects (dislocation loops) were created by ionization processes in addition to those associated with nuclear collisions. The F-center concentration induced by electronic energy excitations was studied at different temperatures and as a function of the particle electronic energy losses. TEM revealed that dislocation loops were produced close to the particle trajectories and amorphization was never observed. On the opposite, in LiNbO3 continuous amorphous tracks were evidenced above a threshold near 5keV/nm. The dependance of this effects with various solid state parameters will be discussed.
Effects of Vacancy-Type Defects on Electrical-Activation of P+ Implanted into Silicon
Authors: Watanabe M. , Kitano T. , Asada S. , Uedono A. , Moriya T. , Kawano T. , Tanigawa S. , Suzuki R. , Ohdaira T. , Mikado T. 
Published: April 2011

AbstractThe effects of vacancy-type defects induced by ion implantation on the electricalactivation of implanted phosphorus by rapid thermal annealing (RTA) are investigated using the positron annihilation technique, secondary ion mass spectroscopy (SIMS) and the spreading resistance (SR) method. P÷ ions are implanted into bare Si wafers and into Si through Si02 films at 700 keV with doses of the order of l×1013 cm−2. After implantation, rapid thermal annealing (RTA) is performed at temperatures between 600 and 1100 °C for 20 sec. The result shows that vacancy-type defects compensate the electrical-activation of P implanted into Si and also recoiled- oxygen is affected on the electrical-activation of P. The species of main defects for compensating the electrical-activation is identified as a divacancy (V2) from the lifetime of positrons. Effects of recoiled oxygen on the electricalactivation are attributed to the formation of vacancy-oxygen complexes just below the SiO2/Si interface and a resultant decrease in the diffusion length of vacancy-type defects.
Surface and Interface Stress in Epitaxial Growth
Authors: Ibach H. , Grossmann. A. 
Published: April 2011

AbstractRecent experimental measurements on the interface stresses in two heteroepitaxial systems have shown that the interface stresses were unexpectedly large. For thin deposited layers, the interface stress can exceed the stress caused by the lattice mismatch by far. Arguments are presented which indicate that the surface stress may be caused by the charge transfer between the deposit and the substrate. The consequences for the critical thickness of pseudomorphic films are discussed and it is shown that depending on the sign of the interface stress and the mismatch the critical thickness can be either reduced or enhanced by a large factor.
Growth of Niobium Films at High Temperatures on Sapphire
Authors: Wagner T. 
Published: April 2011

AbstractThe growth and microstructural evolution of Nb thin films on the basal plane of α-Al2O3were studied at different growth temperatures. The influence of island orientation, density, and misfit strain energy on the growth behavior of Nb films on (0001)α-Al2O3at high temperatures has been investigated. The films were grown by MBE at 900°C and 1100°C. At these temperatures the Nb grows in the Volmer-Weber growth mode on the basal plane.In-situreflection high energy electron diffraction (RHEED), Auger electron spectroscopy (AES) and transmission electron microscopy (TEM) investigations revealed that in the initial growth stage, Nb nuclei with different epitaxial orientations were formed. This leads to different orientations of thicker Nb films at different growth temperatures. At a growth temperature of 900°C the Nb{111} planes are parallel to the sapphire basal plane whereas at 1100°C Nb grows with the {110) planes parallel to the basal plane of sapphire. The formation of two different epitaxial orientations of thick Nb films can only be explained by considering both the change in the total density of Nb islands with temperature and the influence of island size on their total energy.
Evolution of Surface Roughness During CVD Growth
Authors: Chason E. , Mayer T.M. , Adams D.P. , Huang H. , Diaz De La Rubia T. , Gilmer G. , Kellerman B. K. 
Published: April 2011

AbstractMonte Carlo simulations of physical and chemical vapor deposition are used to study roughening kinetics of films that grow by nucleation and coalescence of clusters. The effects of interlayer transport, preferential dissociation of molecular precursors and energetic differences between the clusters and the substrate are examined.
The Effect of Stress on the Nanomechanical Properties of Au Surfaces
Authors: Houston J. E. 
Published: April 2011

AbstractStress in thin films plays a critical role in many technologically important areas. The role is a beneficial one in strained layer superlattices where semiconductor electrical and optical properties can be tailored with film stress. On the negative side, residual stress in thin-film interconnects in microelectronics can lead to cracking and delamination. In spite of their importance, however, surface and thin-film stresses are difficult to measure and control, especially on a local level. In recent studies, we used the Interfacial Force Microscope (IFM) in a nanoindenter mode to survey the nanomechanical properties of Au films grown on various substrates. Quantitative tabulations of the indentation modulus and the maximum shear stress at the plastic threshold showed consistent values over individual samples but a wide variation from substrate to substrate. These values were compared with film properties such as surface roughness, average grain size and interfacial adhesion and no correlation was found. However, in a subsequent analysis of the results, we found consistencies which support the integrity of the data and point to the fact that the results are sensitive to some property of the various film/substrate combinations. In recent measurements on two of the original substrate materials we found a direct correlation between the nanomechanical values and the residual stress in the films, as measured globally by a wafer warping technique. In the present paper, we review these earlier results and show recent measurements dealing with stresses externally applied to the films which supports our earlier conclusion concerning the role of stress on our measurements. In addition, we present very recent results concerning morphological effects on nanomechanical properties which add additional support to the suggestion that near-threshold indentation holds promise of being able to measure stress on a very local level
Low Temperature Annealing of Rh (111) Surfaces
Authors: Tsui Frank , Wellman Joanne , Xu Junhao , Uher Ctirad , Clarke Roy 
Published: April 2011

AbstractWe have studied smoothing kinetics of Rh (111) surfaces during low temperature annealing using in-situ real-time reflection high energy electron diffraction and scanning tunneling microscopy. The initial surface features were produced by low temperature homoepitaxial growth of Rh (111). Two types of surfaces were studied, surfaces with two-dimensional (2D) islands at submonolayer coverages, and those with 3D multilayered features. 2D islands coarsen rapidly at the onset of the anneal. 3D features are more stable initially. Their annealing process exhibits a distinct transition from an initial slow coarsening, characterized by a nearly linear growth of lateral size, to a rapid flattening. The activation energy for the transition is ˜ 0.6 eV. The observed behavior indicates that the smoothing kinetics in the low temperature regime is limited by adatom detachment from the step-edges, and that the fast process for the 3D features is made possible by the formation of a network of “chain-like” structures which provide new pathways for diffusion thus overcoming the slow detachment kinetics. These effects determine the low temperature stability of the non-equilibrium epitaxial morphologies.
Studies of Morphological Instability and Dislocation Formation in Heteroepitaxial Si1−xGex Thin Films Via Controlled Annealing Experiments
Authors: Ozkan Cengiz S. , Nix William D. , Gao Huajian 
Published: April 2011

AbstractHeteroepitaxial Si1−x Gex thin films deposited on silicon substrates exhibit surface roughening via surface diffusion under the effect of a compressive stress which is caused by a lattice mismatch. In these films, surface roughening takes place in the form of ridges aligned along either <100> or <110> directions depending on the film thickness and composition. In this paper, we compare the relaxation behaviour of capped and uncapped heteroepitaxial Si1−xGex thin films containing 22% Ge, with surface roughening being inhibited in films with a capping layer. Films with 50 nm thickness were deposited on bare silicon substrates in a LPCVD reactor. Annealing experiments were conducted in a Hydrogen atmosphere in the reactor chamber. Transmission electron microscopy and atomic force microscopy have been used to study the surface morphology and microstructure of these films. XRD measurements were conducted to determine the amount of relaxation in these films. In-situ transmission electron microscopy/annealing experiments have been performed on uncapped Si1−x Gex/Si structures to study the dynamics of surface roughening and defect formation in a vacuum ambient. Finally, we compare surface morphologies and defects in samples subjected to annealing in vacuum and H2 ambients.
Influence of Chemical Composition on the Epitaxy and Interfacial Quality of Fe/Au and Fe/Ag Multilayers
Authors: Paniago R. , Chow P. C. , Forrest R. , Moss S. C. , Parkin S. S. P. , Cookson D. 
Published: April 2011

AbstractFe/Au and Fe/Ag films grown on MgO(001) oriented substrates exhibit the same in-plane epitaxy since Au and Ag have the same fcc bulk structure and nearly equivalent lattice parameters. Using synchrotron X-ray reflectivity and high-angle Bragg scattering we show that Fe(15Å)/Au(21Å) multilayers grown by sputtering exhibit different profiles for Fe/Au and Au/Fe interfaces. We analyze this in view of the action of Au as a surfactant during the growth of Fe. Similar Fe/Ag multilayers have considerably worse interfacial quality since Fe and Ag do not interdiffuse, and this leads to the result that the interfaces cannot be described by error function profiles. Using non-specular x-ray reflectivity we show that whereas Fe/Au interfaces are self-affine, Fe/Ag interfaces exhibit two regimes of scaling behavior as a function of spatial wavelength. This suggests that two different mechanisms are important in describing the growth of Fe/Ag films.
Nucleation and Pattern Formation of Coherent Islands During Epitaxial Growth of Ge on Si(110) Surfaces
Authors: Weil J. D. , Yang Bi-Ke , Slough C. G. , Krishnamurthy M. 
Published: April 2011

AbstractMolecular beam epitaxial growth of Ge on Si(110) surfaces reveals interesting aspects of the heterogeneous nucleation of coherent Ge islands. Cleaning of the Si substrate by desorption of a passivating oxide layer at high temperature creates surface pits. Two sets of experiments, including deposition of Ge on as-cleaned substrates, and surfaces with a thin Si buffer layer are compared to illustrate the nucleation behavior of Ge. Typical Ge deposition temperatures range from 600°C to 725°C.For Ge deposition on as-cleaned surfaces, the faceted edges of pits serve as preferential sites for the heterogeneous nucleation of coherent Ge islands. Experiments were also performed on surfaces with thin (˜20nm) Si buffer layers grown on the as-cleaned surface. Though the faceted pits have not been completely covered by the Si buffer layer, they have decreased in lateral size. In addition, the Si(110) surface shows ledges that are formed along specific crystallographic directions. Ge deposited on the Si buffer nucleates first at the corners of the pits, in an interesting dipole orientation, as well as along the ledges on the surface.
Growth and Epitaxy of Au on TiO2 (110)
Authors: Cosandey F. , Persaud R. , Zhang L. , Madey T. E. 
Published: April 2011

AbstractThe growth of Au on TiO2 (110) has been examined by high resolution fielc emission scanning electron microscopy (HRSEM) in combination with electror backscattered diffraction (EBSD). The Au was evaporated under UHV conditions onto stoichiometric TiO2 (110) surfaces in the temperature range from 300 to 475 K. At 300 K and for low coverages (<1.5 nm), Au grows as discrete particles. For thicker coverages (>1.5 nm), the particles coalesce to form a network, but percolation is absent even aftel deposition of 5 nm Au. Upon annealing or deposition (≥ 5 nm) at 475 K, the particles, appear clearly faceted and are oriented along specific crystallographic directions. EBSE patterns taken from individual particles reveal two equivalent domain orientations rotated by 180° with epitaxial orientation relationships corresponding to (111)Au//(110)TiO and [110] // [001]TiO2 (Orientation I) and [110] // [001]TiO2.(Orientation II)
Surface Roughening During Titanium Silicide Formation: a Comparison Between Si(100) and Poly-Si Substrates
Authors: Lavoie C. , Martel R. , Cabral C. , Clevenger L. A. , Harper J. M. E. 
Published: April 2011

AbstractWe demonstrate that the formation of TiSi2 for Ti films deposited on undoped Si(100) substrates leads to rougher surfaces than for Ti films deposited on undoped poly-Si substrates. The successive formations of TiSi2, C49 (high resistivity) and C54 (low resistivity) phases from titanium films deposited on either Si(100) or poly-Si substrates were monitored in situ during rapid thermal annealing using elastic light scattering, x-ray diffraction and resistance measurements. For both types of substrates, the roughening occurs only during the formation of the first TiSi2, phase (C49) by light scattered from lateral length scales of ˜0.5 μm. Atomic force microscopy (AFM) images. quantified using Fourier filtering, are consistent with the light scattering results.
Atomistic Structure of High Index Surfaces
Authors: Mutasa Batsirai , Farkas Diana 
Published: April 2011

AbstractInteratomic potentials of the embedded atom (EAM) type were used to study the atomistic structure of high index surfaces in metals and ordered alloys. The results show that a structural unit model can be developed to model the structure of the high index surfaces on the basis of the structure of a few low energy surfaces. The model can predict the structural features and give an estimate of the energies of the higher index surfaces. We present examples of Fe, B2 FeAl and NiAl.
Depth Profile Of Point Defects In Ion Implanted n+p and p+n Junctions Formed By 450°C Post-Implantation Annealing And Impact Of Defects On Junction Characteristics
Authors: Oka Mauricio Massazumi , Nakada Akira , Tamai Yukio , Kanemoto Kei , Shibata Tadashi , Ohmi Tadahiro 
Published: April 2011

AbstractIt is shown that defects generated by ion implantation, remaining after annealing at low temperature, are deep-distributed in the bulk silicon and their amount is demonstrated to be function of the substrate type and the implanted ion species. The confirmation that defects penetrate deeply into the silicon is made by a new method that consists in damaging by ion implantation a previously formed pn junction that shows very low leakage current and has a deep junction. It is proposed that the dopants in the substrate act as nucleation centers for the formation of point defect clusters and that these clusters actually degrade the junction. It was found that point defects penetrate much more deeply in p+n junctions than in n+p junctions. It was also found that BF2+ introduces much more defects into the silicon than As+, owing to the presence of fluorine. The leakage currents at 5 V of n+p and p+n diodes made by implantation of P+ and B+, respectively, could be lowered by one to two orders of magnitude with respect to values obtained by implantation of As+ and BF2+ because the former ones produce less defects than the latter.
Effects Of Gettering On Device Characteristics
Authors: Horikawa Mitsuhiro , Yaoita Akihiko , Nagata Tsuyoshi , Kitano Tomohisa 
Published: April 2011

AbstractEffective methods of gettering metallic impurities were proposed. To achieve effective gettering, an annealing process to induce gettering was modified taking fundamental gettering steps and the difference in the gettering mechanism into account. As the concentration of heavy metal is below solubility in a state-of-the-art clean room, a combination of segregation type gettering and slow cooling heat treatment is an effective technique to remove metal impurities from the device active region. Using this technique, DRAM device characteristics such as leakage current and data retention time can be improved.
Investigation On Subsurface Damage In Silicon Wafers
Authors: Zhang Xin , Zhang Tong-Yi , Zohar Yitshak , Lee Sanboh 
Published: April 2011

AbstractMicro-Raman spectroscopy and chemical etching were applied to determine the depth of subsurface damage in silicon wafers undergoing different machining processes: cutting, grinding, polishing and lapping. In comparison with the Raman spectrum of perfect single crystal silicon, both the shape and intensity at the shoulder (500 cm−1) and the subpeak (300 cm−1) spectral regions were changed in all the machined wafers. The intensities at shoulder and subpeak gradually decreased and finally resumed to normal, as the depth of the investigated layer increased. According to the chemical etch rate, the depth of the subsurface damage was thus evaluated for the different wafers. TEM observations further confirmed the obtained results.