bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pd2Si on Si(111) Growth Kinetics Studied by X-Ray Diffraction
Authors: Coulman Betty , Chen Haydn 
Published: March 2011

AbstractResults are presented for the kinetics of growth of Pd2Si interfacial layers obtained by an X-ray diffraction technique. Epitaxial Pd2Si films were grown on Si(111) substrates over a temperature range of 160–222°C. The parabolic rate law observed is in qualitative agreement with those reported by investigators using other techniques (RBS, AES, Electron Microprobe). There appear to be two kinetics regimes distinquished by diffusion paths with different activation energies (1.35±0.10 eV vs. 1.05± 0.10 eV). The presence of impurities and the detailed Pd 2Si microstructure will influence how the reacting species are transported through the lattice.
Surface Characterization of Arsenic Implanted Silicon (100): A New Insight into the Inhibition of Aluminum/Silicon Interdiffusion
Authors: Herbots Nicole , Gloesener D. , Van Loenen E. J. , Fischer A. E. M. J. 
Published: March 2011

AbstractArsenic segregation at Si(lO0) surfaces during annealing (890–970°C) has been studied by medium energy ion scattering (MEIS), Rutherford backscattering spectrometry (RBS), ion scattering spectrometry (ISS), and Auger electron spectroscopy (AES). The unique depth resolution of MEIS revealed that arsenic segregated in a two-dimensional layer at the clean Si surface during annealing. For a surface with a native oxide the arsenic piled up at the Si/oxide interface. This segregation peak was no longer present on the Si surface after conventional contact opening. By metallizing arsenic junctions with Al:Si, 1% it was found that a segregation annealing step inhibited Al/Si interdiffusion. Diodes as shallow as 180 nm could be metallized without spiking.
The Disordering Process in an Ll2 Ordered Alloy
Authors: Horton J. A. , Dasgupta A. , Liu C. T. 
Published: March 2011

ABSTRACTThe antiphase boundary (APB) structure and the disordering process have been studied by transmission electron microscopy (TEM) in a long-rangeordered alloy with Ll2 structure and composition (Ni70Fe30)3(V58Al40Ti2). With an increase in temperature from a single-phase field into a two-phase field, disordering occurs both homogeneously within ordered domains and heterogeneously along APBs. Disordering continues by a ripening process with the disordered islands shrinking while the disordered bands on the prior APBs grow. The APBs are partially aligned on {100} while the material is single phase. As disordering proceeds, the degree of alignment of the disordered bands on {100} increases until complete alignment results. A correlation of the APB structure with room temperature mechanical properties indicates no dramatic change at the transition to the two-phase structure.
The Disordering Phase Transformation in (Ni70Fe30)3(V98-xAlxTi2) Alloys with 0 < × < 80
Authors: Dasgupta A. , Horton J. A. 
Published: March 2011

ABSTRACTThe sequence of disordering transformation processes in the A3B type alloy series (Ni70Fe30)3(V98-xAlxTi2), currently under development for high-temperature structural applications, was studied by differential scanning calorimetry (DSC), x-ray diffraction, optical microscopy, and transmission electron microscopy (TEM). Results of DSC show that in all alloys there are two endothermic stages of phase transformation from the ordered to the disordered state. With increasing x, the disordering transition temperature, Tc, reaches a maximum ∼1000°C at x ≈ 50, and then decreases. Interrupted heating, followed by water quenching, was used to characterize the crystal structure and the microstructure of the intermediate phases. For the x + 20 alloy, TEM observations showed ordered regions of DO22 phase in a matrix of disordered fcc (Al) phase at intermediate temperatures. The ordered domains transformed morphologically into cuboid like regions at higher temperatures. From a combined study by all the techniques, we conclude that in alloys with x between 0 and 20, the sequence of phase transformations upon heating is: DO22 → DO22 + Al → Al, whereas in alloys with x > 40, the major sequence is Ll2 + B2 → Ll2 + Al → Al.
DO3-domain Structures in Fe3Al-X Alloys
Authors: Mendiratta Madan G. , Lipsitt Harry A. 
Published: March 2011

ABSTRACTThe influence of a number ternary additions in Fe3Al upon the DO3 domain structures and DO3 → B2 transformation temperature, Tc, has been investigated. It was found that additions in (atomic percent) of 5 Ti, 5 Cr, 6 Mn, 12 Mn, 10 Ni, 3 Mo, 6 Mo, 3 Si, and 5 Si raise Tc. In the Fe-20 Al-5 Ti alloy not only is Tc raised significantly (≧ 750°C), but the DO3 antiphase domain boundaries with fault vector become highly crystallographic and are parallel to {100} planes.
Plastic Flow of L12Ordered Alloys
Authors: Pope D. P. , Vitek V. 
Published: March 2011

ABSTRACTThe flow stress of many L12ordered alloys has a very unusual temperature dependence: the flow stress increases with increasing temperature. This unusual behavior is related to the nature of dislocation dissociation and core structure. The flow stress increase is the result of thermally activated cross slip of [101] screw dislocations to the (010) plane which is accompanied by a transformation of the dislocation core from a glissile to a sessile form. Thus dislocations which are mobile on (111) planes become immobile after cross-slip into (010) planes. The dependence of the flow stress on temperature, orientation and sense of the applied uniaxial stress will be discussed in the light of this cross slip model for Ni3Al, Ni3Ga and for γ/γ′ nickel base superalloys.The response of Ni3Al to cyclic plastic strains (plastic strain controlled fatigue) will also be shown to be in accord with the cross slip model. The mean stress in such a test becomes compressive or tensile, depending on the orientation of the sample, even though the net plastic strain is zero after each cycle.The strengthening of Ni3Al by ternary additions will also be discussed. It will be shown that ordinary solid solution strengthening models are not applicable but that the cross slip model can also be applied.Finally, it will be shown that dislocation core simulation studies predict that there should also be a class of L12ordered alloys that show a “normal” flow stress-temperature behavior, i.e., the flow stress increases at low temperatures. The results of our studies on Pt3Al will be used to illustrate this behavior.
Wear Induced Deformation of Ni3Al, (Fe, Co)3V, and (Fe, Ni)3V
Authors: Marquardt B. J. , Werta J. J. 
Published: March 2011

ABSTRACTSeveral experimental techniques have been implemented in order to compare the tribological response of Ni3Al, (Fe, Co)3V, and (Fe, Ni)3V to commercial engineering alloys. Abrasive and adhesive macrowear behavior during sliding contact has been determined. Microstructural data obtained from transmission electron microscopy (TEM) and scanning electron microscopy (SEM) have been correlated with macrowear results. In this correlation, consideration was given to the effects of wear on long-range-order and the presence (or absence) of dislocation subcell structures. The formation of dislocation subcell structures is partially related to the material's stacking fault energy (SFE) which has been the basis of recent wear theory. An experimentally verified wear mechanism based on inhomogeneous slip is defined.
Characteristic Mechanical Properties and Phase Stability of L12Intermetallic Compounds
Authors: Mishima Yoshinao , Oya Yoshihiro , Suzuki Tomoo 
Published: March 2011

ABSTRACTThe present paper deals with the occurence and magnitude of characteristic mechanical anomalies observed in many L12intermetallic compounds and their relation to the phase stability of the crystal structure against other geometrically closed packed(GCP) phases. The dislocation configurations in the crystal structure and resultant plastic behavior are in close relation with anti-phase boundary(APB) and stacking fault(SF) energies in the compounds, while the relative magnitude of these energies on various crystallographic planes actually determines the phase stability of the L12crystal structure. It is shown here, based on our series of investigations carried out over the past decade, that the general tendencies for particular deformation modes to occur can be systematically interpreted in terms of alloy chemistry of the compounds, including variables such as combination of component species, nonstoichiometry and ternary additions in the compounds, all of which affect the stability of the phase.
Damping and Modulus Measurements in B2 Transition Metal Aluminides
Authors: Harmouche M. R. , Wolfenden A. 
Published: March 2011

ABSTRACTThe polycrystalline intermetallic alloys FeAl (50.9 to 58.2% Fe), NiAl (49.2 to 55.9% Ni) and CoAl (48.5 to 52.3% Co) have the B2 structure and are of interest for high temperature applications. We have used the PUCOT (piezoelectric ultrasonic composite oscillator technique) to measure mechanical damping or internal friction (Q−) and Young's modulus (E) as a function of temperature and composition for these materials. The modulus data for six CoAl alloys at temperatures up to 1300 K are presented. Examples are given of the strain amplitude dependence of Q−1 for four CoAl alloys. The curves showed the break away phenomenon and are interpreted in terms of a theory dealing with the pinning of dislocation lines and their eventual break away at large strain amplitudes. The dislocation density was calculated to be about 108 m−2. For all the compositions (Xl) of CoAl studied a single equation could be fitted to the data:E (X1, T) = 210.8 + 2.2 (XI) -0.08T (1)where T is in K and E in GPa.
Alloys based on NiAl for High Temperature Applications
Authors: Vedula K. , Pathare V. , Aslanidis I. , Titran R. H. 
Published: March 2011

ABSTRACTThis paper presents some of the results obtained in an on-going study of NiAl alloys for potential high temperature applications. Alloys were prepared by powder metallurgy techniques. Flow stress values at slow strain rates and high temperatures were measured. Some promising ternary alloying additions (Hf, Ta and Nb) have been identified. The mechanism of strengthening in alloys containing these additions appears to be a form of particle dislocation interaction. Interesting effects of grain size and stoichiometry in binary alloys are also presented.
On the Feasibility of AB Initio Calculations of Ordering Alloy Phase Diagrams
Authors: Fontaine D. de 
Published: March 2011

ABSTRACTMany stable or metastable intermetallic phases useful to the alloy designer have crystal structures which are ordered superstructures of a parent disordered phase. A highly reliable statistical mechanical method (CVM) has now been developed for calculating such superstructure phase equilibria derived from say, the fcc parent lattice. To obtain phase diagrams, one needs certain physical parameters, such as effective pair interaction ratios. It is possible, in principle, to extract these parameters from band structure calculations in the coherent potential approximation (CPA), particularly from recently developed cluster-CPA techniques. If sufficient accuracy can be achieved, truly first-principles phase diagram calculations may soon become feasible.
Weldability of Ni3Al-Type Aluminide Alloys
Authors: Santella M. L. , David S. A. , White C. L. 
Published: March 2011

ABSTRACTIf the ductile Ni3Al-based aluminides are to achieve their full potential as engineering materials, they must demonstrate a capability for being joined by conventional welding processes. The goal of this study was to identify some of the factors controllinq weldability of the ductile aluminides. The alloys selected for this initial study were boron-doped Ni3 Al and Ni3 Al containing 10 at. % Fe. Sheet stock was used to make full penetration autoqenous welds by the electron beam and gas tungsten arc processes. The main process variables were travel speed and preheat. The aswelded coupons were examined visually and by normal metalloqraphic methods. Although sound welds were made, initial results indicated weldments of these alloys are susceptible to cracking. Weldability of the ductile Ni3Al-based aluminides was found to be affected by alloy composition and welding speed.
Synchrotron X-Ray Study of the Structure of Silicon During Pulsed Laser Processing
Authors: Larson B. C. , White C. W. , Noggle T. S. , Barhorst J. F. , Mills D. 
Published: March 2011

ABSTRACTSynchrotron x-ray pulses have been used to make nanosecond resolution time-resolved x-ray diffraction measurements on silicon during pulsed laser annealing. Thermal expansion analysis of near-surface strains during annealing has provided depth dependent temperature profiles indicating >1100°C temperatures and diffraction from boron implanted silicon has shown evidence for near-surface melting. These results are in qualitative agreement with the thermal melting model of laser annealing.
Competition Between Solid Phase Epitaxy and Random Crystallization During cw Laser Annealing of Amorphous Si Films
Authors: Roth J.A. , Kokorowski S.A. , Olson G.L. , Hess L.D. 
Published: March 2011

ABSTRACTThe kinetics of amorphous-to-polycrystalline conversion and solid phase epitaxy (SPE) in UHV-deposited Si films have been determined over a wide temperature range by the use of optical reflectivity measurements made during rapid heating by a cw Ar laser. Crystallization rates measured in UHV following film deposition are reported and compared to rates measured in air in order to elucidate the effects of contaminants on the processes. The effects of boron doping on nucleation and growth kinetics are also reported. The crystallization rates determined in these studies can be used to predict the volume fraction of polycrystalline material formed during laserinduced SPE growth of thick epitaxial layers.
Structural Modifications of Amorphized Silicon Surfaces Following Picosecond Laser Irradiation
Authors: ROZGONYI G.A. , Baumgart H. , Phillipp F. , Uebbing R. , Oppolzer H. 
Published: March 2011

ABSTRACTWe have used cross-section TEM and Nomarski optical microscopy to examine the origin of halo patterns previously observed following picosecond irradiation of ion implantation amorphized Si. The importance of melt depth, quench rate and the incomplete nature of the initial amorphization step are emphasized. A search for a post annealing morphological or microstructural signature related to a plasma activated process proved negative.
Transient Conductance Measurements During Pulsed Laser Annealing
Authors: Thompson M. O. , Galvin G. J. , Mayer J. W. , Hammond R. B. , Paulter N. , Peercy P. S. 
Published: March 2011

ABSTRACTMeasurements were made of the conductance of single crystal Au-doped Si and silicon-on-sapphire (SOS) during irradiation with 30 nsec ruby laser pulses. After the decay of the photoconductive response, the sample conductance is determined primarily by the thickness and conductivity of the molten layer. For the single crystal Au-doped Si, the solid-liquid interface velocity during recrystallization was determined from the current transient to be 2.5 m/sec for energy densities between 1.9 and 2.6 J/cm2, in close agreement with numerical simulations based on a thermal model of heat flow. SOS samples showed a strongly reduced photoconductive response, allowing the melt front to be observed also. For complete melting of a 0.4 μm Si layer, the regrowth velocity was 2.4 m/sec.
Pulsed X-Ray Annealing of Arsenic-Implanted Silicon
Authors: Sigmon T. W. , Osias D. E. , Schneider R. L. , Gilman C. , Dahlbacka G. 
Published: March 2011

ABSTRACTIn this paper we report experiments on annealing of arsenic-implanted silicon using a pulsed imploding-plasma X-ray source. Silicon wafers of <100> orientation were implanted with arsenic ions at 50 keV to a dose of 3.5 ∼ 1015 cm−2 and exposed to a single 50 ns pulse of X-rays in the energy density range of 0.15 to 0.55 J/cm2 The characteristic X-ray absorptiog coeificient in silicon for these experiments was 1.6 ∼ 10 cm−1, resulting in most of the energy being absorbed in the first 100 nm of the wafer surface.For wafers annealed in the energy density range of 0.3 to 0.4 J/cm2 backscattering and channeling measurements show recovery of the crystallinity of the damaged layer with incorporation of about 86% of the implanted arsenic onto substitutional lattice positions. Evidence of redistribution and flattening of the arsenic profile in the annealed wafer was observed in the backscattering data and confirmed by SIMS profiling. Detailed results on the electrical and structural properties of these annealed layers will be presented. High energy pulsed X-ray sources offer the unique capability of simultaneously exposing large numbers of wafers to an extremely uniform energy flux at much higher efficiencies than conventional lasers.
On the Influence of Laser Beam Homogenity on the Regrowth of Ion Implanted Si
Authors: Wielunski M. , Auleytner J. , Tjros A. , Wielunska D. 
Published: March 2011

ABSTRACTA simple method of improving laser beam homogenity has been developed. A cylindrical quartz pipe, acting as a lightguide, has been applied for dispersion of the components of the laser beam (microbeams), thus providing more uniform illumination of the sample's surface. The effects of such a homogenizer have been studied by means of X-ray transmission topography [4–5] and 2-MeV 4 He-ion channeling. The samples were ≤111≥ Si wafers implanted with 100 keV As and Bi ions to a dose of 1016 /cm2 . It has been observed that the shallow residual damage layer which exists in the directly irradiated samples is not present in the samples irradiatedthrough the homogenizer.
Divacancy Annealing in Crystalline Silicon Using E-Beam and Pulsed Ruby Laser Excitation
Authors: Stein H. J. , Knapp J. A. , Peercy P. S. 
Published: March 2011

ABSTRACTAnnealing of divacancies which were produced by 11B ion implantation was investigated under furnace, pulsed e-beam and pulsed ruby laser exposures. Despite orders of magnitude shorter exposure times for annealing and the concomitant expected high levels of electronic excitation and layer stress, we find that the thermal annealing mechanism observed for furnace annealing is an adequate description for divacancy annealing under e-beam exposure. The observed need for melting to remove divacancies by Q-switched laser annealing is also consistent with predictions based upon extrapolations from furnace annealing.
Electronic Defects in Beam - Crystallized Silicon
Authors: Johnson N. M. 
Published: March 2011

ABSTRACTDirected energy sources have been used to recrystallize implanted amorphous layers in bulk single - crystal silicon and to crystallize silicon thin films on insulating amorphous substrates. All investigated forms of beam annealing leave residual electronic defects in and near the recrystallized layer on bulk silicon, with densities in excess of those obtained by conventional furnace annealing. This paper summarizes the general observations that may be drawn from numerous experimental investigations of electronic defects in CW beam - recrystallized bulk silicon and affirms the timeliness of similar comprehensive studies of residual defects in crystallized - silicon thin films.
Superconducting Effects in Rapidly Quenched Materials Formed by Ion and Laser Bombardment
Authors: Stritzker Bernd 
Published: March 2011

ABSTRACTThe application of low temperature ion bombardment and pulsed laser or electron beam irradiation for the production of rapidly quenched superconducting alloys is described and compared with other more conventionally used non-equilibrium techniques. The comparison is based on the identification of the metastable phases produced by their specific electrical and superconducting properties. It is concluded that low temperature heavy ion bombardment is comparable with vapor quenching whereas laser quenching yields results similar to liquid quenching. Finally, the interesting superconducting properties of these rapidly quenched metastable alloys are discussed.
Space-Time Resolved Reflectivity Measurements of Picosecond Laser Induced Phase Transitions in <111> Silicon
Authors: Yen R. , Liu J. M. , Kurz H. , Bloembergen N. 
Published: March 2011

ABSTRACTThe changes in reflectivity of a silicon surface, irradiated by a green picosecond pulse, are probed during and following that pulse with a spatial resolution of 10μm. The data indicate the development of a liquid phase, and a resolidification either into a single crystal or an amorphous phase. The latter has a characteristic ring-type pattern, and occurs only at locations where the incident picosecond laser fluence lies between 0.2 and 0.26 J/cm2. The reflectivity data appear to be in good quantitative agreement with a “simple heating” model, in which the electrons and phonons maintain a local thermodynamic equilibrium on a picosecond time scale.
Laser-Induced Liquid Zone Migration of Metal-Silicon Alloys in Si
Authors: Kluge-Weiss P. , Roggwiller P. 
Published: March 2011

ABSTRACTPatterns of sharp narrow vertical p-n junctions were produced by scanning a laser beam over the surface of a silicon wafer coated on the backsurface by either Au-Sb, Al or Ga. Formation of the junctions occurs by liquid zone migration along the thermal gradient induced by the laser beam. Nd-YAG as well as CO2 laser light was employed and the dependance of migration zone width, velocity, front stability and structure on the different laser wave lengths was studied. Structural investigations of the regrown layers included optical microscopy, SEM and TEM studies as well as spreading resistance measurements to ascertain the behaviour of the various p-n junctions produced. Annealing treatments of the migrated zones were performed to alleviate the stresses produced during the migration experiments.
CO2 Laser Crystallization of Silicon on Bulk Fused Silica
Authors: Hawkins William G. , Black Jerry G. , Griffiths Clifford H. 
Published: March 2011

ABSTRACTA CO2 laser beam was used to heat bulk fused silica which had previously defined Si3N4 and Si02 encapsulated LPCVD polysilicon islands (25,μm × 100μm) on its surface. The recrystallization process produces single crystal islands under a wide variety of laser treatment parameters. Under certain conditions, the recrystallized islands exhibit a (100) plane parallel to the substrate. These results are the first demonstration of oriented single crystal thin film growth using island predefinition, which eliminates thermal stress induced microcracking resulting from the mismatch in expansion between silicon and bulk fused silica.
Fast Scanned Energy Beam Induced Explosive Crystallization of Ion Implantation Amorphized Poly and Single Crystal Silicon Substrates
Authors: Lerme M. , Ternisien D'ouville T. , Vu Duy-Phach , Perio A. , Rozgonyi G.A. , Nguyen V. T. 
Published: March 2011

ABSTRACTExplosive crystallisation induced by an electron beam and by a CW Ar+ laser operating in fast scanning mode is observed for the first time on amorphized silicon layers created by implantation on either polycrystalline films deposited on Si02 or single crystal silicon substrates. The grain structure in the explosive crescents is studied by preferential chemical etching in conjunction with Nomarski optical microscopy, SEM and TEM. The results are similar to the so-called solid-phase explosive crystallization previously observed in a-Si films deposited on glass substrates.