bluuebunny/crossref_metadata_2025_split huggingface dataset:
High-Tc Superconducting Films Irradiated with Low-Energy Oxygen Ion Beam
Authors: Phedotova V. V. , Zoubetz A. V. , Ges A. P. , Stognij A. I. 
Published: March 2011

ABSTRACTLPE-grown YBCO single crystal films were irradiated with oxygen ion beam up to a fluence level of 8 × 1019 cm−2 Irradiation parameters were as follows: , beam energy 0.8 keV, current density 0.4 mA/cm2. Ultimate vacuum was not less than 5 × 10−6 Torr, operating vacuum was 2 × 10−4 Torr. Tc = 53K and transition width ΔT> 10 K characterized the starting state of the films. After irradiation Tc was found to increase up to 94 K and Δ to decrease down to 0.5 K. Proceeding from transition character one can conclude that the irradiated film composition was changing into a single phase one. Half widths of the characteristic peaks of x-ray spectra were decreasing with the increase in fluence. The best results were obtained upon the irradiation of cooled samples. Upon heating the samples up to 600° C it was impossible to obtain Tc = 86 k and ΔT = 2 K.
RBS/Channeling Characterization of Ba Implanted Mg
Authors: Da Silva R. C. , Hauser Th. , Melo A. A. , Soares J. C. , Da Silva M. F. , Meyer O. 
Published: March 2011

ABSTRACTThe behaviour of 300 keV Ba ions implanted at room temperature with doses between 1015 and 1017 cm−2 in Mg single crystal and foils was investigated. The results show that the Ba ions do not occupy substitutions sites in Mg, either after the implantation or the annealing treatments. However, pronounced migration of Ba to the surface is observed above 380 °C. The remaining fraction overlaps with the aa-implanted distribution and forms small precipitates. This behaviour is not correlated with the recovery of the Mg lattice which is already complete at about 250 °C. The surface segregation of Ba delays the evaporation of Mg to temperatures near the melting point.
The Effect of Digm and Irradiation-Induced Grain Growth on Interdiffusion in Bilayer Ion-Beam Mixing Experiments
Authors: Alexander Dale E. , Rehn L. E. , Baldo Peter M. , Gao Y. 
Published: March 2011

ABSTRACTExperiments were performed demonstrating that ion irradiation enhances diffusion-induced grain boundary migration (DIGM) in polycrystalline Au/Cu bilayers. Here, a model is presented relating film-averaged Cu composition in Au with treatment time, grain size and film thickness. Application of this model to the experimental results indicates that irradiation enhances DIGM by increasing the grain boundary velocity. The effects of DIGM and irradiation-induced grain growth on the temperature dependence of ion mixing in bilayers are discussed.
A Universal Criterion for Amortization in Metallic Systems
Authors: Kulp D. T. , Egami T. , Luzzi D. E. , Vitek V. 
Published: March 2011

ABSTRACTRecent computer simulation studies of electron-bombarded metallic alloys have concentrated on finding a criterion for amorphization. It has been suggested that the thermodynamic properties of volume and total energy can be used as a gauge for defect induced amorphization. Our simulation results indicate that these properties can not be used due to their dependence on processing history. We propose that the distribution of the atomic level shear stresses can be used as this amorphization criterion. Using Finnis-Sinclair type many-body potentials and Lennard-Jones pair potentials, molecular dynamics (MD) simulations on several model systems have been performed. By quantifying the analysis using the average shear stress normalized, by the average shear modulus of the glass, we will present evidence that the crystal becomes amorphous at the defect concentration where the normalized average shear stress reaches a critical value, which is equivalent to the state obtained through quenching from the liquid.
Surface Chemical Routes to Low Contamination Beam Assisted GaAs Etching
Authors: Marshall Duncan , Jackman Richard B. 
Published: March 2011

ABSTRACTIn-situ processing requires totally dry approaches to pattern generation to be developed. Of particular interest are beam driven reactions that can be localised without prior masking. This paper considers the adsorption - desorption characteristics of chlorine, dichloroethane and sulphuryl chloride on GaAs(lOO). The surface reactivity in these systems is seen to vary considerably. The implications of this are considered with regard to their use as chemically assisted ion beam and laser photochemical etching gases.
Dopant and Strain Dependence of Extended Defect Generation in Silicon by 1-MeV Electron Irradiation
Authors: Vanhellemont Jan , Romano-Rodriguez Albert 
Published: March 2011

ABSTRACTResults are presented of an in-situ study of 1-MeV electron irradiation induced {113}-defect generation in silicon with boron, phosphorus or arsenic doped surface layers. By 1-MeV electron irradiation in a high voltage transmission electron microscope, {113}-defects are dorni-nandy formed in areas with a well defined dopant concentration range which depends on the tjpe of dopant atom, the irradiation temperature and fluence and the sample thickness. The observations for samples with boron and phosphorus concentration profiles are compared with published data on electron irradiation induced ( 113}-defect formation in uniformly doped silicon. In the present paper first results on heavily arsenic doped silicon are presented. It is shown that ihe observed dopant dependence of the {113}-defect generation can be understood on the basis of known point defect reactions. A few irradiation experiments are also performed on a local isolation structure illustrating for the first time the influence of localised tensile and compressive strain fields on {113} -defect nucleation.
Detailed Model for Ion-Beam Induced Adatom Generation
Authors: Breeman M. , Boerma D. O. 
Published: March 2011

ABSTRACTIn earlier low-energy ion scattering experiments of 6 keV Ne ions on Cu(100), Cu adatoms were observed to appear on the surface. The number of produced adatoms per incoming ion was found to decrease to 50% of its initial value of 3.5 after prolonged irradiation. In this paper we present calculations of the adatom production as a function of irradiation dose. From a comparison with the experimental data, the trapping radius of a vacancy was determined to be 5.4 ± 0.9 Å, in agreement with values reported in the literature.
XPS-Analysis of Ion-Beam-Induced Oxidation (IBO) of AlxGa1−xAs Substrates
Authors: Alay Josep-Lluis , Vandervorst Wilfried 
Published: March 2011

ABSTRACTXPS analysis was used to characterise GaAs, Al0.4Ga0.6As and Al0.8Ga0.2As targets bombarded with an O2+ beam ranging from 1 keV to 5 keV. The bombardments were carried out at different angles of incidence from 0° to 60°. In all cases a strong preferential sputtering of arsenic gives rise to an As-depleted altered layer, formed by a mixture of gallium, arsenic and aluminium oxides with metallic gallium and arsenic. Aluminium and gallium are preferentially oxidized, a fact that correlates with the corresponding heat of formation of the oxides, whereas the arsenic oxidation requires a minimum incorporation of oxygen into the matrix. For all experimental conditions a considerably lower oxidation level has been observed in every case as compared to the IBO of silicon.
The Effect of Structural Relaxation on the Diffusion of Au in Amorphous Pd80Si20
Authors: Wagner A. V. , Spaepen F. 
Published: March 2011

ABSTRACTThe diffusivity of Au in sputter-deposited amorphous Pd80Si20 has been measured by Rutherford backscattering spectrometry (RBS) between 275°C and 380°C. A new method based on scaling of the evolution of the variance of the concentration profile was used to analyze the data. The diffusivity was found to be independent of the Au concentration below 3 at.%. Structural relaxation causes a time dependence that is evident at short times. The kinetics of this relaxation can be described by the bimolecular relaxation model used in the analysis of viscous flow.
Excimer Laser Surface Modification: Process and Properties
Authors: Jervis T. R. , Nastasi M. , Hirvonen J.-P. 
Published: March 2011

ABSTRACTSurface modification can improve materials for structural, tribological, and corrosion applications. Excimer laser light has been shown to provide a rapid means of modifying surfaces through heat treating, surface zone refining, and mixing. Laser pulses at modest power levels can easily melt the surfaces of many materials. Mixing within the molten layer or with the gas ambient may occur, if thermodynamically allowed, followed by rapid solidification. The high temperatures allow the system to overcome kinetic barriers found in some ion mixing experiments. Alternatively, surface zone refinement may result from repeated melting-solidification cycles.Ultraviolet laser light couples energy efficiently to the surface of metallic and ceramic materials. The nature of the modification that follows depends on the properties of the surface and substrate materials. Alloying from both gas and pre-deposited layer sources has been observed in metals, semiconductors, and ceramics. Surface enrichment of Cr by zone refinement of stainless steel has also been seen. Rapid solidification after melting often results in the formation of non-equilibrium phases, including amorphous materials. Improved surface properties, including tribology and corrosion resistance, are observed in these materials.
Congruent Melting Temperatures of Si-As Alloys Measured During Pulsed-Laser Melting and Rapid Solidification
Authors: Kittl J. A. , Reitano R. , Aziz M. J. , Brunco D. P. , Thompson M. O. 
Published: March 2011

ABSTRACTThe solidification of Si-As alloys induced by pulsed laser melting was studied at regrowth velocities where the partition coefficient is close to unity. The congruent melting temperatures, TO, of Si-As alloys were determined using a temperature measurement technique developed for this work, and were confirmed with TOmeasurements using three other methods. The time-resolved temperature measurement uses a thin-film platinum thermistor, below and electrically isolated from the Si-As alloy layer, to directly measure the temperature during solidification. This, combined with measurements of transient conductance of the Si-As alloy, time-resolved reflectivity and Rutherford Backscattering Spectrometry, permitted the determination of the solid-liquid interface temperature, velocity and partition coefficient, the latent heat of fusion and TO for Si - 4.5 at. % As and Si - 9 at. % As alloys.
CW Laser-Induced Removal of Interconnections in Submicron Devices
Authors: Auvert Geoffroy 
Published: March 2011

ABSTRACTThe interaction of a cw argon-ion laser with the materials used in the microelectronics technology is described as a pyrolytic effect. A chemical reaction is induced between the oxide layer and the hot irradiated silicon or aluminum line. By making a cross section of the irradiated area using a focused ion beam, the formation of an unstable insulating material covering the conducting material is observed.
Modification of Fused Silica Materials for Excimer Laser Optics—measurement of laser induced defects and its reformation—
Authors: Matsumoto Yasutaka , Yoshikado Yoshihiro , Murahara Masataka 
Published: March 2011

ABSTRACTFused silica is widely used material in window and lens applications for excimer laser processing. The transmittance of the laser beam in fused silica is attenuated approximately 40% by high fluence ArF excimer laser irradiation. The attenuation of the transmittance corresponds to the growth of an absorption band at 215nm. This phenomenon is troublesome for laser lithography. To investigate this effect, we examined the laser induced luminescence and absorption under various conditions. The 215nm absorption band was diminished by annealing at 900 °C for 2 hours in He ambient. Ke could successfully obtain good optical material, whose transmittance remains constant with increasing ArF laser(193nm) shot exposure.
Point Defects in GaAs and Other Semiconductors
Authors: Ehrhart P. , Karsten K. , Pillukat A. 
Published: March 2011

ABSTRACTIn order to understand the properties of intrinsic point defects and their interactions at high defect concentrations GaAs wafers were irradiated at 4.5 K with 3 MeV electrons up to a dose of 4.1019 e-/cm2. The irradiated samples were investigated by X-ray Diffraction and optical absorption spectrocopy. The defect production increases linearly with irradiation dose and characteristic differences are observed for the two sublattices. The Ga-Frenkel pairs are strongly correlated and are characterized by much larger lattice relaxations (Vrel=2–3 atomic volumes) as compared to the As-Frenkel pairs (Vrel ≈ 1 at.voL). The dominating annealing stage around 300 K is attributed to the mobility of the Ga interstitial atoms whereas the As-interstitial atoms can recombine with their vacancies only around 500 K. These results are compared to those for InP, ZnSe and Ge. Implications for the understanding of the damage after ion irradiation and implantation are discussed.
Limitations to the Bandgap-Selective Photoelectrochemical Etching of GaAs/AlxGa1−x as Heterostructures
Authors: Khare Reena , Young D. Bruce , Hu Evelyn L. 
Published: March 2011

ABSTRACTWe have used the wet photoelectrochemical (PEC) etch process to demonstrate the selective removal of low aluminum (Al) mole-fraction AlxGa1−xAs layers from those with higher Al mole-fraction. High etch selectivity was found for δx as low as 0.05, but was found to decrease as the incident photon energy approached the energy bandgap of the desired stop-layer. The ultimate selectivity of one layer from an underlying layer was affected not only by differences in material composition, but also by the sequencing of the layers within the structure.
In Situ Studies of Electron Cyclotron Resonance Plasma Etching of Semiconductors by Spectroscopic Ellipsometry
Authors: Nafis S. , Ianno N. J. , Snyder Paul G. , Woollam John A. , Johs Blame 
Published: March 2011

ABSTRACTIn situ ellipsometry at selected wavelengths in the spectral range 280 nm to 1000 nnn was performed during the rf bias assisted electron cyclotron resonance (ECR) etching of bulk silicon, GaAs, InP, and GaAs/AlGaAs/GaAs, and InGaAs/InP layered strcutures by a CCl2F2 based etch gas.While real time thickness changes for bulk materials cannot be determined ellipsometrically, some insight into the etch mechanism may be gained by observing the effect of the process on the surface dynamically, and after the etch process has been completed. Monitoring of the layered structures during etching can provide a real time measure of the amount of material remaining in the layer being etched, and provide tight process control.
Remote Plasma Cleaning and Ion-Induced Hydrogen Desorption from the Silicon (100) Surface and Its Applications to Si Epitaxy
Authors: Kinosky David S. , Qian R. , Mahajan A. , Thomas S. , Fretwell J. , Munguia P. , Banerjee S. , Tasch A. 
Published: March 2011

ABSTRACTWe have studied the conditions for effective removal of H from the silicon (100) surface by Ar and He plasma bombardment as a function of pressure, plasma power and time. At a given pressure, a range of rf plasma powers exists for effective H-desorption. For example, at 250°C and for 100 mTorr of He, H is desorbed only between 12 and 50W of plasma power. The range of effective powers was found to become narrower with increasing pressure. We have also found the efficacy of the H-plasma clean to be reduced by addition of He and Ar. Substrate damage results from Ar addition and from increased plasma power for pure H. The results are discussed along with Langmuir probe analysis of the various plasma conditions.
Excimer Laser Induced Cryoetching of GaAs and Related Materials
Authors: Freiler Michael B. , Shih Ming Chang , Scarmozzino R. , Osgood R. M. , Tao Ie Wei , Wang Wen I. 
Published: March 2011

ABSTRACTWe report highly resolved, damage-free etching of GaAs and related materials. The etching is activated by excimer laser irradiation at 193 nm of samples maintained at low temperatures (∼140 K) in a chlorine atmosphere (∼5 mTorr). Since the etching is chemical in nature, structural damage to the substrate should not be present. Submicrometer resolution has been achieved by the use of electron beam lithography to pattern a Si3N4 contact mask. We have also successfully used our etching in the fabrication of a single-quantum-well, ridge-waveguide semiconductor laser.
Characterization of Films Made from Silicon Oil Saturated Methane Vapor by Ion Beam
Authors: Lin Sin-Shong , Sloan Janes M. 
Published: March 2011

ABSTRACTAmorphous carbon films were prepared by the ion beam deposition of methane saturated with silicon pump oil 704. The concentration of Si in the ion deposited coatings could be varied by the temperature of silicon oil bath where saturated vapor was produced. In the process, the vapor ionized at 800 V was accelerated and impinged on glass or stainless steel substrates at ion densities between 0.3–1.5 mA/cm2 for a period of less than 60 minutes. The resulting films were characterized by x-ray photoelectron and Raman spectroscopies. The elemental components of these films include carbon, oxygen and silicon with varying amounts of nitrogen, iron and tungsten contaminations. The microstructure mainly consists of tiny graphitic carbon with sp2 ordered and disordered configurations, numerous carbon-oxygen and carbon-silicon linkages. This simple unique process yields a homogeneous thin coating suitable for many tribological applications.
Stabilization of Metastable Zinc-Blende Phase MnTe by Ionized Cluster Beam Deposition
Authors: Ando K. , Takahashi K. , Takeuchi Y. 
Published: March 2011

ABSTRACTThe ionized cluster beam (ICB) deposition was use to stabilize the metastable zinc-blende (ZB) MnTe films directly on GaAs (100) substrates at 300 °C with MnTe cluster ion beam. Influences of the ionization and the acceleration voltage on film properties were investigated by the reflection high-energy electron diffraction (RHEED), optical reflection, Raman scattering, and photoluminescence. The ZB-MnTe was stabilized by 3kV acceleration of the MnTe cluster beam. These results showed that the ICB deposition is useful to get compounds having crystalline phase different from the structures observed io equilibrium-grown bulk crystals.
An Assessment of ECR Argon Plasma Etching Damage on Si and SiO2 Interfaces
Authors: Nam C. W. , Ashok S. , Tsai W. , Day M. E. 
Published: March 2011

ABSTRACTElectron cyclotron resonance (ECR) argon plasma has been used (to etch the native oxide on Si and thermal SiO2. The Schottky barrier height modification on both n- and p-Si has been studied as a function of substrate bias and etch time. Deep Level Transient Spectroscopy (DLTS) measurements show clear peaks on both p- and n-Si, but wish low levels of trap concentrations (1012-1013cm−3), and decreasing with depth from the surface. The effects of thermal oxide etching on the Si/SiO2 interface have been estimated with MOS capacitors. Negative flat-voltage shift is observed after argon plasma exposure, which removes the thermal oxide at a rate of over 100 Å/min at 50 V bias. C-V measurements show an order of magnitude increase in interface trap density.
Fabrication and Evaluation of Ternary Co-Fe-Si Structures Produced by Ion Beam Synthesis
Authors: Hunt Tim D. , Sealy Brian J. , Hanebeck Jochen , Reeson Karen J. , Homewood Kevin P. , Gwilliam Russell M. , Meekison C. Douglas , Roger Booker G. 
Published: March 2011

ABSTRACTDual implantation of cobalt and iron into silicon (100) wafers and subsequent annealing has been used to form layers containing mixtures of CoSi2 and FeSi2. The structure and properties of the layers were followed by Secondary Ion Mass Spectrometry (SIMS), cross-sectional transmission electron microscopy (XTEM), Transmission Electron Diffraction (TED), Rutherford Backscattering Spectroscopy (RBS), and photoluminescence (PL). When a high dose of both species was implanted, segregation of the cobalt and iron occurred which for 1000°C anneals, resulted in an epitaxial layer of αFeSi2 upon a CoSi2 layer. The epitaxial quality of both of these layers was superior to those previously fabricated by single species implants. For a low dose cobalt implant followed by a high dose iron implant, a single phase solid solution was formed and segregation did not occur. Photoluminescence at 1.54 urn was observed from this layer, but with a much lower intensity and a broader line width than that from a pure βFeSi2 layer.
The Dynamic Compaction of Metallic Powders
Authors: Morris David G. 
Published: March 2011

ABSTRACTThe Dynamic Compaction of powdered materials becomes a particularly attractive technique for consolidating hard materials, because of the ease with which high pressures are achieved, and for metastable materials, because of the possibility of avoiding large-scale, high temperature excursions. The shock-wave conditions necessary for achieving high densities and interparticle bonding are evaluated experimentally. The bonding and melting taking place can be identified by post-consolidation studies, and the inter-relation between compact integrity and melting is shown. An attempt is made to develop a “process window” analogous to that of explosive bonding, to describe the conditions necessary for consolidation. Finally, in view of the necessity for localisation of plastic flow during consolidation, an indication of the influence of material deformation parameters is given.
Influence of Short Range Order, Electron Concentration and Size Misfit on the Structure and Thermal Stability of Metallic Glasses
Authors: Bergmann H. W. , Luft U. , Fritsch H. U. 
Published: March 2011

ABSTRACTThe influence of short range order, electron concentration and size misfit on the thermal stability of (Fe100-xMx)83B17 metallic glasses has been investigated (M = Cr, Mn, Co, Ni, Mo, W). The results are discussed together with Curie-temperature measurements and Mößbauer spectroscopy data. The concentration range in which the various stable and metastable phases form is given.
Rapid Solidification Of Composite Materials
Authors: Zielinski Piotr G. , Ast Dieter G. 
Published: March 2011

ABSTRACTThe melt spinning technique was used to prepare composite materials consisting of a metallic glass matrix and a second phase in the form of particles and/or C or SiC fibers. The spatial distribution of the second phase varied with the method used to incorporate the particles into the melt. The observed distributions can be explained by assuming that rotational stirring takes part in the melt puddle. The influence of second phase on the effective quenching rate is discussed and the mechanical properties of Ni75Si8B17 glass containing a variety of second phase particles are reported.
Effect of R-Curve and Inhomogeneities on the Toughness Measurement of Metallic Glasses
Authors: Henning W. , Calvo M. , Osterstock F. 
Published: March 2011

ABSTRACTSub-critical crack growth is a function of the degree of relaxation of the amorphous structure and has implications regarding the measurement of annealing embrittlement and the dependence of embrittlement on temperature. The variation of Kc with annealing time is strongly dependent on the size of the initial crack length. Quenched-in inhomogeneities seem to be always present. Their effect depends on the specific testing conditions, especially the testing temperature because the ductile-brittle transition is a function of the degree of relaxation of the amorphous structure. Some doubt is also cast on the accepted assumption that a chevron pattern is representative of plane strain crack propagation conditions.