bluuebunny/crossref_metadata_2025 huggingface dataset:
Energy Dependence of Amorphization of Ge by Kr Ions
Authors: Birtcher R. C.
Published: March 2011

Thin Ge specimens have been irradiated with Kr ions of different energies, and the dose required for complete amorphization determined by in situ transmission electron microscopy. Because Ge is directly amorphized by a single energetic Kr ion, onset of amorphization was detected after the lowesi ion doses. The Kr dose required for complete amorphization was found to increase linearly with ion energy over the range 0.5 MeV to 3.5 MeV. With the assumption that the defect density required for amorphization is independent of ion energy, the number of defects produced in a thin specimen by each ion decreases with increasing energy as the reciprocal of the incident ion energy. TRIM calculations indicate that there is a slight decrease in the amount of damage required with increasingion energy.
Mechanism of Dose-Rate Dependence of Electrical Activation in Ion-Implanted GaAs
Authors: Kanayama Toshihiko , Tanoue Hisao
Published: March 2011

To elucidate the mechanism of dose rate (DR) dependence of electrical activation, following two questions are investigated; why the amount of damage remaining after ion bombardment depends on DR and why it affects the electrical activation after high temperature annealing. From the observation that the DR dependence scales with temperature, the activation energy of recovery during ion irradiation has been estimated to be 0.75 and 1.0 eV. A higher DR suppresses the recovery and results in more damage, which in turn delays the electrical activation of implanted impurities.
Ion Species Dependence of Electrical Characteristics in Ion Implanted GaAs
Authors: He L. , Anderson W. A.
Published: March 2011

Fluorine, boron and oxygen implantation in GaAs has been investigated by electrical characterization using current-voltage (I-V), capacitance-voltage (C-V) and deep level transient spectroscopy (DLTS) techniques. Ion implantation at lOOkeV energy was conducted with doses of 1011 and 1012/cm2. Carrier compensation was observed in each implanted sample. The compensation effect strongly depended on ion implantation conditions and ion species. Severe surface damage was also induced which degrades electrical performance. Rapid thermal annealing (RTA) treatment showed the heavier ion implanted samples to be more thermally stable. Defect levels for each implanted species were compared and identified.
Residual Damage in Heavily Germanium-Doped Silicon
Authors: Demirlioğlu Esin , Aronowitz Sheldon , Su David
Published: March 2011

Cross-sectional transmission electron microscopy (XTEM) studies have shown that two distinct damage regions are created when germanium is implanted into single-crystal silicon in high doses and subsequently annealed at high temperatures. The first layer extends approximately 90–95 nm into silicon for an implant energy of 120 keV. The second region is an end-of-range damage region located 200 nm from the silicon surface for the same implantation energy. Neither low-dose, low-energy boron implantation nor the type of cap layers used during annealing alter the damage pattern. Although the dose of the Ge implants is the major factor in the formation of the continuous damage layer, high oxygen concentration at the surface may also contribute to this effect.
The Enhanced Outdiffusion and Its Influence on the Impurity Behavior in the Implanted Si at Rapid Electron Beam Annealing
Authors: Kagadey V. A. , Lebedeva N. I. , Proskurovsky D. I. , Yakovleva L. V.
Published: March 2011

The paper presents the results of a comprehensive study of the outdif-fusion of volatile impurities (P, As, Sb) from originally amorphous ion-implanted layers (IILs) of Si at rapid electron-beam heating in vacuum. The phenomenon of enhanced outdiffusion has been discovered and the activation energy of this process has been measured. It has been established that there exists an interconnection between the process of activation, deactivation, diffusion and segregation of the impurity in IIL and its outdiffusion. A qualitative model of the process determining this interconnection has been proposed. The reasons for the lowering of the potential barrier at the IIL-vacuum interface determining the abnormally high rates of vaporization of the impurity have been supposed.
Defect Elimination by MeV Ion Implantation
Authors: Saito S. , Kumagai M. , Kondolt T.
Published: March 2011

In the p-type shallow junction formation using B+ implantation, preamorphaization is an essential technique to suppress B+ channeling. The crucial problem in this process is defect formation at an amorphous-crystal(a-c) interface. We have demonstrated that MeV ion implantation is effective to reduce defects for shallow junction formation. F+ preimplantation at 40 KeV with 1×l015 cm−2 was effective to form p-type shallow junctions by B+ implantation at 10 KeV with 5×1015cm−2. However, defect formation induced boron diffusion and also leakage current increase. These problems were overcome by MeV ion implantation at 1 MeV F+ or Si+ with 5x×1015 cm−2, followed by rapid thermal annealing at 1000–1100°C for 10 seconds. In the P preimplanted samples, followed by MeV ion implantation, defects at the a-c interface can be reduced and an about 50 % shallower junction depth was obtained, compared with just B+ implanted samples. The results indicate that MeV ion implantation is effective to form a shallow junction with a low leakage current.
Computer Simulation of Channeling Effects in Ion Implantation
Authors: Posselt Matthias
Published: March 2011

Our binary collision code Crystal-TRIM is applied to simulate 1 MeV P+ implantation into single-crystalline silicon at ion incidence into the [100] axial channel direction and doses between 2 × 1013 cm−2 and 6.7 × 1014 cm−2. The maximum penetration depth of the ions is determined by the electronic stopping of the well-channeled particles. The shape of the range distributions depends on (i) the thin amorphous surface layer on silicon, (ii) the radiation-induced production of vacancies and interstitials, and (iii) the static atomic disorder due to electronic energy deposition. The comparison of experimental data with results of computer simulations shows that at low doses at least the influence of the first two factors has to be considered. At higher doses the radiation damage due to nuclear energy deposition dominates the other effects.
High-Effective Ion-Implanted 6H-SiC Light Emitting Diodes with λmax=535nm
Authors: Suvorov A. V. , Ivanov P. A. , Makarov V. N. , Plotkin D. A. , Ioffe A.
Published: March 2011

The p-n structures was formed by the implantation of Al ions into 6H-SiC n-type films and the thermal annealing. An energy of ions was in the range of 40–90 KeV, an annealing temperature -1700–2100K. We investigated the influence of implantation conditions over the defects electroluminescence of the obtained structures.

After fabricating contacts and mesa-structures with areas 500–500μm our devices showed under the current of 20 mW:

- integral light power 20μW,

- λmax=535 nm, δλmax=80nm.

For the first time was fabricated the green electroluminescence source on SiC with the value of efficiency approximated to one of the A3B5 structures, and after encapsulating it will be possible to obtain LEDs with an integral light power up to 80–100μW.
Ion Beam Synthesis of IrSi3 by Implantation of 2 MeV Ir Ions+
Authors: Sjoreen T. P. , Hinneberg H.-J. , Chisholm M. F.
Published: March 2011

The formation of a buried IrSi3 layer in (111) oriented Si by ion implantation and annealing has been studied at an implantation energy of 2 MeV for substrate temperatures of 450–550°C. Rutherford backscattering (RBS), ion channeling and cross-sectional transmission electron microscopy showed that a buried epitaxial IrSi3 layer is produced at 550°C by implanting ≥ 3.4 × 1017 Ir/cm2 and subsequently annealing for 1 h at 1000°C plus 5 h at 1100°C. At a dose of 3.4 × 1017 Ir/cm2, the thickness of the layer varied between 120 and 190 nm and many large IrSi3 precipitates were present above and below the film. Increasing the dose to 4.4 × 1017 Ir/cm2 improved the layer uniformity at the expense of increased lattice damage in the overlying Si. RBS analysis of layer formation as a function of substrate temperature revealed the competition between the mechanisms for optimizing surface crystallinity vs. IrSi3 layer formation. Little apparent substrate temperature dependence was evident in the as-implanted state but after annealing the crystallinity of the top Si layer was observed to deteriorate with increasing substrate temperature while the precipitate coarsening and coalescence improved.
Optical Bleaching of Bismuth Implanted Silica Glass: A Threshold Effect
Authors: Park S. Y. , Magruder R. H. , Weeks R. A. , Zuhr R. A.
Published: March 2011

The near surface regions of high purity silica glass discs, Spectrosil A, were modified by implantation with bismuth ions at 160 keV and room temperature. The glasses implanted with a nominal dose of 6×1016 Bi/cm2 at ∼5 μA/cm2 were subsequently bleached with a 5.0 eV KrF pulsed excimer laser. The laser had an average pulse duration of -20 ns and repetition rate of 10 Hz. It was found that the bleaching was dependent upon the power density of the laser for a constant total integrated energy. Ion backscattering and optical absorption measurements were made before and after laser irradiation. Large changes in optical density and depth distribution of the implanted ions were observed at power densities of ≥45 mJ/cm2-pulse. On the basis of our experimental results, the onset of the threshold for bleaching of silica glass implanted with 6×1016 Bi/cm2 at 160 keV and at room temperature is between 30 and 45 mJ/cm2-pulse.
Characterization of Thermal Annealed Bi Implanted Silica
Authors: Morgan S. H. , Henderson D. O. , Pan Z. , Magruder R. H. , Zuhr R. A.
Published: March 2011

Optical and infrared reflection spectra for Bi implanted silica are reported as a function of dose and thermal annealing. A series of high purity silica samples were implanted with Bi ions at an energy of 350 KeV. Doses were 1 × 1016 and 1.0 × 1017ions/cm2 at 5μamps/cm2. The samples were subsequently thermally annealed at 400, 600 and 800 C. The optical absorption from 6.2 to 1.8 eV and infrared reflectance from 5000 to 450 cm”−1 were measured before and after annealing. Effects of thermal annealing are strongly dependent on Bi content.
Characterization of Diamond Amorphized by Ion Implantation
Authors: Allen William R. , Lee Eal H.
Published: March 2011

Single crystal diamond has been implanted at 1 MeV with 2×1020 Ar/m2. Rutherford backscattering spectrometry in a channeled geometry revealed a broad amorphized region underlying a thin, partially crystalline layer. Raman spectroscopy disclosed modifications in the bonding characteristic of the appearance of non-diamond carbon. The complementary nature of the two analysis techniques is demonstrated. The Knoop hardness of the implanted diamond was reduced by implantation.
Design of a Large-Scale Plasma Source Ion Implantation Experiment
Authors: Wood B. P. , Scheuer J. T. , Nastasi M. A. , Olsher R. H. , Reass W. A. , Henins I. , Rej D. J.
Published: March 2011

In Plasma Source Ion Implantation (PSII), a target to be implanted is immersed in a weakly ionized plasma and pulsed to a high negative voltage. Ions in the plasma are accelerated toward the target and implanted in its surface, thereby modifying the properties of the surface. Experimental results reported in the literature have generally been for small targets. We present here the design of a large-scale PSII experiment being assembled Los Alamos National Laboratory, in which we plan to implant targets with surface areas exceeding 1 m2 to doses of up to 5 × 1017 cm−2. In presenting this design, we use Monte Carlo and particle-in-cell simulations to examine sheath expansion, implant current and dose, secondary electron emission, target sputtering, implant depth, and x-ray emission resulting from secondary electrons hitting the vacuum chamber wall.
Microstructure of Heat-Affected Zone in Carbon Steel Irradiated by a Low-Energy High-Current Electron Beam
Authors: Ivanov Yu. F. , Itin V. I. , Lykov S. V. , Markov A. B. , Rotshtein V. P.
Published: March 2011

Using X-ray structural analysis and transmission electron microscopy of thin layers we have studied the mechanism of heat-affected zone formation in as-hardened steel irradiated by a low-energy microsecond high-current electron beam. It has been found that the above zone consists of three characteristic layers. We have analysed the conditions of formation of this layers using thermal calculations.
Lattice Site of Helium Implanted in Si and Diamond
Authors: Allen William R.
Published: March 2011

Single crystals of silicon and diamond were implanted at 300K with 70 keV 3He. Ion channeling analyses were executed by application of Rutherford backscattering spectrometry and nuclear reaction analysis. Helium exhibits a non-random lattice site in the channeling angular distributions for silicon and diamond. A major fraction of the implanted 3He was qualitatively identified to be near to the tetrahedral interstice in both materials.
Defect Creation and Electron Trapping in Single Crystal and Sintered Alumina by Electron Beam Irradiation
Authors: Carroll D. L. , Doering D. L. , Xiong-Skiba P.
Published: March 2011

Electron beam irradiation of oxides produces electron trapping states which store excess charge. Thermionic emission of this charge occurs during heating with emission peak temperatures related to binding mechanisms and energies. We present thermionic emission results which show both intrinsic and beam induced trapping states in OC-Al2O3 (sapphire) and sintered alumina. Five states have been identified with thermionic emission peaks at temperatures between -50°C and 500°C. Two states are electron beam induced and occur only for electron beam energies above fixed thresholds. These thresholds appear to correlate to with the Is core electron binding energies for oxygen and aluminum. The emission peaks from the sintered material are about 10 fold greater in intensity and slightly broadened in comparison to the single crystal. This suggests that structure plays an important role in charge trapping. Emission was also extremely sensitive to sample treatments such as annealing before electron irradiation.
Parameters for Nitrogen Diffusion in Ni, Ti, and Al Obtained from Implanted Bilayers
Authors: Bourdelle K. K. , Boerma D. O.
Published: March 2011

Ni foils and samples consisting of bilayers of Ni or Fe on Al, Ti or Si were implanted at room temperature with 15N+ ions to fluences of around 1×l017 N/cm2. The concentration depth profiles of 15N were determined with nuclear reaction analysis before and after vacuum annealing. It was found that the penetrability for N atoms of the surface and the solid/solid interface plays an important role in the N redistribution during implantation or annealing. The formation of a nitride layer or nitride clusters in Ni and Fe was deduced. Parameters for N migration determined for the metals under investigation are discussed in terms of models.
Epitaxial Phase Formation of FeSi2 in an Fe-Implanted Si by Ion Irradiation and Rapid Thermal Annealing
Authors: Lin X. W. , Behar M. , Desimoni J. , Bemas H. , Swider W. , Liliental-Weber Z. , Washburn J.
Published: March 2011

Si (001) wafers were implanted at room temperature with 50-keV Fe ions to different doses and subsequently crystallized either by rapid thermal annealing (RTA) (900°C, 120 s) or by Si+ irradiation (500 keV, 320 °C). Transmission electron microscopy, as well as Rutherford backscattering and channeling, were used to study the phase formation of FeSi2 in Si. Depending on the implantation dose and the crystallization process, three phases of FeSi2 were produced. While RTA results in the formation of β-FeSi2, ion irradiation promotes the growth of either cubic FeSi2 phase for low implantation doses (< = 4 at.% Fe) or a-FeSi2 for high implantation doses (≈18 at.% Fe). All these phases of FeSi2 were found to grow epitaxially in the Si matrix and their orientation relationships relative to Si have been determined. The interfacial energy between FeSi2 and Si appears to be an important factor in determining the final structure of FeSi2.
Microstructure of Zr3Al After 2 MeV Proton Bombardment
Authors: Chen F. C. , Ardell A. J. , Pedraza D. F. , Buhl R. A.
Published: March 2011

The ordered intermetallic Ll2 alloy Zr3Al was irradiated with 2 MeV protons at -124 °C to fluences up to 2 × 1015 H+/mm2 and at 250 °C to fluences up to 1 × 1015 H+/mm2. Defects with spherically symmetric strain fields were produced at both irradiation temperatures. They are of interstitial character at -124 °C and vacancy character at 250 °C. Disordering is induced at -124 °C, whereas irradiating at 250 °C initially lowers, then slightly raises, the degree of long-range order above its unirradiated value. Additional defects that appear as black spots were imaged using superlattice reflections in dark field. For the low-temperature irradiations they were seen at all doses, but were present at only the lowest close for the high-temperature irradiations. They are probably disordered zones, although some of the zones may be amorphous at the higher doses in the low-temperature irradiations.
Resolution Limits of Focused-Ion-Beam Resist Patterning
Authors: Kubena R. L.
Published: March 2011

We have recently demonstrated the ability to focus a 50-keV Ga+ beam to an 8-nm-diameter spot diameter. This ultra-high resolution probe has been used to study the resolution limits of conventional resists for focused-ion-beam lithography. Lines and dots in poly (methylmethacrylate) resist as small as 7–8 nm have been formed with high throughput. In addition, no proximity effects have been observed for 25 to 30-nm size features on high-z substrates. However, for the smallest geometries obtainable, the pattern fidelity and resolution are most likely limited by ion scattering effects and statistical dose fluctuations. The use of lighter ions (such as He, Li, or Be) with lower sensitivity resists should, in principle, allow focused-ion-beam lithography to be extended to the sub-5 nm regime.
Creation of 3D Patterns in Si by Focused Ga-Ion Beam and Anisotropic Wet Chemical Etching
Authors: Chen Wei , Chen P. , Madhukar A. , Viswanathan R. , So J.
Published: March 2011

We report the realization of free standing 3D structures as tall as ∼ 7μm with nano-scale thickness in Si using the technique of Ga focused ion beam implantation and sputtering followed by wet chemical etching. Some of the previously investigated subjects such as anisotropie etching behavior of crystalline Si and etch stop effect of Ga+implanted Si etched in certain anisotropie chemical etchants have been further explored with the emphasis on exploiting them in realizing free standing structures. The design and fabrication considerations in achieving such free standing structures are discussed and some typical structures fabricated by this technique are shown.
Novel Materials Synthesis Using an Intense Pulsed Ion Beam
Authors: Gautier D. C. , Muenchausen R. E. , Rej D. J. , Roberts B. F. , Johnston G. , Waganarr W. J.
Published: March 2011

Initial experiments on the evaporation from metallic and ceramic targets using a pulsed light ion beam source is reported. The source is an intense ion beam produced by a 1.2 MV, 300 kJ Anaconda generator which has been fitted with an extraction diode.

Beam fluences of 10–20 J/cm2 give a deposition rate of about 30–50 nm per shot, for both brass and YBa2Cu3O7-x (1–2–3) targets. This is about 1000 times greater than comparable rates from pulsed laser deposition (PLD). Single-shot ablated 1–2–3 films, deposited on Si, were analyzed using RBS; the measured stoichiometry was close to 1–2–3 in favorable cases, but shot-to-shot reproducibili ty was poor.

Approximately 1% of the available ion beam energy was utilized for these initial experiments. The potential for producing large area coatings from multi-cation targets and nanophase powders using pulsed ion beam deposition will be discussed.
Laser Solid-Phase-Epitaxy of Amorphous Si1−xGex layer on Si
Authors: Sogoh Yasunori , Murakami Kouicbi , Nasuda Kohzoh
Published: March 2011

Laser Solid-phase-epitaxy (SPE) of amorphous Si1−xGex layer on Si formed by the molecular beam deposition (MBD) method was successfully performed by cw-Kr laser irradiation. Laser SPE of small areas was achieved by Laser irradiations of short time durations and high power densities The strain in the Laser-SPE layers was evaluated by micro-Raman scattering. It is demonstrated that strained SiGe layers on Si can be grown in the central area of 10μm size within the area crystallized by Laser- SPE at a substrate temperature of 400°C after preannealing at 350°C for 15 to 30 minutes.
Ion Beam Sputtering of Erbium Doped Fluoroaluminate Glass Films
Authors: Moore M. W. , Davey S. T. , Rothwell W. J. M. , Cannard P. J.
Published: March 2011

Ar ion beam sputtering has been used to deposit fluoride glasses films up to a micron in thickness on silica and silicon substrates, Fluorozirconate films were found to be dark in colour, attributed to the presence of reduced chemical species. Fluoroaluminate films composed of fluorides less susceptible to reduction were clear and fluorescence from a layer doped with 2 wt% Er3+ is presented.
Angular Distribution of Electrons Elastically Scattered from Copper Surfaces, Polished and Textured by Argon Flux
Authors: Krainsky Isay L.
Published: March 2011

Angular distributions of the elastically scattered secondary electrons from two kinds of Cu surfaces, polished and textured by 2 keV Ar+ have been studied in the energy range from 50 eV to 2 keV. The results show that for the polished Cu surface the elastic scattering process is dominated by atomic scattering from single atoms (although, contributions from othei processes are also important). However when the textured surface was studied, new multiple peaks appeared on the angular distributions. Positions of these peaks for the various angles of incidence and primary energies indicate that their origin lies in the diffraction of the primary electrons on some kind of a polycrystalline structure. This structure is probably created by the process of recrystallization induced by ion sputtering similar to the sputtering induced crystallization process already known for some oxides and nonmetallic compounds.
Deep-Penetration Mechanism of Ion-Irradiation Defects in Al0.3Ga0.7As/GaAs Heterostructure Investigated by In Situ Hall Measurement
Authors: Kanayama Toshihiko , Takeuchi Yukihiro , Sugiyama Yoshinobu
Published: March 2011

Two-dimensional electron gas 60–120-nm deep from the surface was irradiated with 10-keV Ar ions (projected range = 8.8 nm) and resulting change in the mobility was analyzed. Defect distribution thus obtained is exponential in depth with the larger penetration length for the lower irradiation temperature. In-situ Hall measurements revealed that the mobility decreases simultaneously with the irradiation at 90 K. Consequently, the deep penetration of defects is concluded to be mainly due to the ion channeling. Results of iso-chronal annealing indicate that thermal diffusion of the defect that affects the mobility takes place at around 340–400 K, whereas the mobility starts to recover at ∼120 K.
Shock Consolidation of Powders - Theory and Experiment
Authors: Vreeland T. , Kasiraj P. , Ahrens Thomas J. , Schwarz R. B.
Published: March 2011

A recently proposed model of shock consolidation of powders quantitatively predicts regimes of input energy and shock duration required to produce well-bonded compacts. A growing data base from shock experiments in which the shock wave and powder parameters of importance are controlled allows evaluation of the model.

Rapidly solidified crystalline AISI 9310, and microcrystalline Markomet 3.11, as well as amorphous Markomet 1064 and crystalline Mo powders, have been consolidated by shocks up to 2 μsec duration. The formation of amorphous layers on Marko 3.11 particle surfaces indicates that surface melting and rapid solidification occurred. Decreasing amounts of amorphous structure are retained in Marko 3.11 and 1064 powder compacts with increasing shock energies. Significant improvement in Mo particle bonding is achieved by reducing surface oxides prior to shock consolidation.
Kinetics of Solidification at Rapid Rates
Authors: Peteves S.D. , Alvarez J. , Abbaschian G.J.
Published: March 2011

A novel technique was used to measure directly the interface temperature and growth rate during solidification of pure gallium. The technique utilizes the Seebeck emf generated across two solid-liquid interfaces to determine the interface supercooling and an optical microscope to measure the solidification rates. The growth rate measurements were made in the range of about 0.08 to 1400 μm/s for 1.59 to 3.6°C interface supercoolings (ΔT) on the (111) interface of high purity gallium in glass capillaries. A plot of logv vs. 1/T for dislocation-free interfaces followed two straight lines, one for higher than about 1 μm/s growth rates and the other for the lower rates. The data at the lower rates correspond to the lateral growth mechanism for which a single nucleus forms and spreads across the interface before formation of the next nucleus, while those at the higher solidification rates correspond to the lateral growth by the multi-nucleation and spreading mechanism.
Alloying Effects on the Hardness and Ductility of Metallic Glasses
Authors: Mordike B. L. , Hunger G.
Published: March 2011

Hardness and ductility in Fe-M-B alloys were found to be directly dependent on the strength of the metal-metalloid bonding. This behaviour, as well as the annealing embrittlement, can be explained by the localized viscous flow model of heterogeneous deformation.
Some Fundamental Considerations During Rapid Solidification Processing
Authors: Laxmanan V.
Published: March 2011

Three estimates of the solidification rates required to obtain a fully homogeneous structure during rapid solidification processing (RSP) have been made. One is given by the “absolute stability” criterion and another obtained from a new analysis for dendritic solidification. The third estimate, also derived from the above analysis, requires that “hypercooled” conditions be maintained after nucleation. A mechanism for the formation of “featureless” segregation-free zones during melt spinning and atomization processes is suggested and expressions for the critical cooling rate and thermal gradient required to produce such structures have been obtained.
Corrosion Behavior of Rapidly Solidified Fe-Ti-P Alloys With Cu, Cr, and B Additions
Authors: Shastry C. R. , Latanision R. M. , Townsend H. E.
Published: March 2011

Rapidly solidified ribbons of Fe67Ti13P(20-x)Bx (x= 0, 7, 20 a/o) and Fe(85-y)Ti l5Py (y=5, 10 a/o) alloys were produced by melt spinning, and their structure and anodic polarization behavior were examined by x-ray diffraction and potentio-dynamic polarization measurements in deaerated 1 N H2SO4, respectively. The only alloy that developed an amorphous structure on rapid solidification, Fe67Ti13B20, exhibited poor corrosion resistance, whereas crystalline alloys with 10 a/o or more P exhibited a tendency to passivate during anodic polarization. Substituting Cr for Ti led to significant improvement in corrosion resistance and promoted development of glassy structures in Fe67(TiCr)13P13B7 compositions. No such improvements were observed when Cu was substituted for Ti. It is concluded that alloy composition is more important than degree of crystallinity in determining corrosion resistance.
Studies of Relaxation of Metallic Glasses by Dilatometry and Density Measurements
Authors: Cahn R.W. , Pratten N.A. , Scott M.G. , Sinning H.R. , Leonardsson L.
Published: March 2011

High-precision density measurements on coldrolled Pd77.5Cu6Si16.5 glass rods before and after relaxation anneals showed that 30 – 40% rolling leads to a density reduction of ∼0.14%, recoverable on subsequent annealing below Tg. This change is about half of the density increase attainable by recovery-annealing the as-quenched glass.

Density changes in Fe40Ni40B20 glass ribbon, resulting from recovery-annealing, were studied indirectly by measuring isothermal length changes through dilatometry of foil sandwiches. The experimental conditions for reliable isothermal dilatometry, using a commercial instrument, are outlined. It was found that the kinetics of length change in the longitudinal and transverse directions were quite different, being faster in the former. Prolonged recovery-annealing prior to dilatometry removed this difference. The intermediate stage of each isotherm followed loqt kinetics.

Experiments were performed with Fe40Ni40B20, Ni64Zr36 and Cu66Ti34 to search for a reversible component of length change during cyclic isothermal holds at two temperatures. Such a component probably exists but is extremely small, less than 1% of the limiting irreversible length change.

The implications of the various findings are discussed in the light of recent literature.
Glassy Pd-Y-Si Alloys and Their Relaxation and Crystallization Kinetics
Authors: Gao Y.Q. , Giessen B.C.
Published: March 2011

Pd-Y-Si glasses with a Si content as low as 9 at.% were produced by hammer and anvil quenching, the reduction of the Si concentration from a minimum value of 14 at.% in binary Pd-Si alloys was due to the synergistic effect of the addition of Y. The glass forming composition region is reported.

The alloy Pd2Y,Si, was studied in detail. The change of the microhardness upon isothermal annealing was investigated. Isothermal and non-isothermal heating experiments yielded activation energies of 52 and 53 kcal/mol (218 and 222 kJ/mol) in good agreement with each other and an Avrami exponent n = 3.7 was found.
Measurement Of Precipitate Nucleation Times In Molten Metals By Pulsed Surface Melting
Authors: Follstaedt D.M. , Picraux S.T. , Peercy P.S. , Knapp J.A. , Wampler W.R.
Published: March 2011

The short melt duration resulting from pulsed laser and electron beam surface melting of ion-implanted metals has been used to measure precipitate nucleation times of compounds within the melt. We have examined the phases present in several alloy systems with TEM and used calculated thermal histories to place limits on the time required for nucleation of the following compounds: AlSb (5–25 ns), Al3Ni (≳ 750 ns)Al3Ni2 (≳ 950 ns) and AlNi (< 1000 ns), all in molten Al, and TiC (≲ 100 ns) in molten Fe. The compounds observed after our rapid solidification have relatively simple, cubic structures and melt congruently, while those predicted but not observed have more complex structures and decompose peritectically.
Phase Decomposition in Cu-Ti Metallic Glass
Authors: Shull R. D. , Singhal S. P. , Mozer B. , Maeland A.
Published: March 2011

A metallic glass ribbon of Cu55Ti45 prepared by melt spinning was examined by x-ray, neutron, and electron diffraction, by small angle neutron diffraction (SANS), transmission electron microscopy (TEM), and by differential thermal analysis (DTA). In the liquid quenched condition large angle diffraction data (both x-ray and neutron) show the broad banded structure typical of the amorphous state. The SANS data, however, exhibit highly anisotropic patterns arising from the phase decomposition during solidification. Ribbons annealed below the glass transition temperature (Tg ) produced neutron diffraction patterns of materials with the same amorphous structure combined with a new short range order; and the SANS patterns retained the asymmetry of the as-quenched material. Ribbons annealed above the crystallization temperature (Tc) show both isotropic and anisotropic contributions to the SANS patterns. Formation of the equilibrium TiCu phase occurs directly from the metallic glass at Tc. The equilibrium Ti3Cu4 phase, however, forms from the TiCu phase at slightly higher temperatures.
Some Aspects Of The Rapid Solidification Of Light Alloys
Authors: Jones H.
Published: March 2011

The engineering light metals, especially aluminium and magnesium, exhibit limitations in alloying behaviour and performance that identify them as particular targets for development via rapid solidification. The present contribution reviews recent work in the author's group aimed at advancing understanding of both alloying and processing, including:

(1) parametric mapping as a guide to extension of phase fields

(2) prediction and application of observed characterisation of binary and ternary extended solid solutions

(3) optimisation and control of conditions during rapid solidification and consolidation,
Cooling Rate Effects on Ti-6A1-4V and Beta III Titanium Alloys
Authors: Broderick T. F. , Froes F. H. , Jackson A. G.
Published: March 2011

The titanium alloys Ti-6A1-4V and Ti-11.5Mo-6.0Zr-4.5Sn (Beta III) were produced at cooling rates of 103°C/sec and 105°C/sec using the Rotating Electrode Process (REP), and the Electron Beam Splat Quenching (EBSQ) process, respectively. Material from both alloys examined in the as-produced, heat treated, and vacuum hot pressed (VHP) conditions exhibited an order of magnitude decrease in beta grain size with increasing cooling rate (~135 μm and 7 μm in the Ti-6A1-4V alloy; ~40 μm and 2–4 μm in the Beta III alloy), and a difference in aging response between REP powder and EBSQ flakes. After heat treatment the Ti-6A1-4V developed an alpha morphology which was lenticular in REP powder and equiaxed in EBSQ flakes. Three possible mechanisms are proposed to explain this change involving an increased dislocation density and a tendency for grain boundary allotriomorphic alpha in the EBSQ case. Heat treatment of the Ti-11.5Mo-6.0Zr-4.5Sn materials showed a change in the location of alpha precipitation from interdendritic to grain boundary in going from REP to EBSQ. It is suggested that this change may relate to the decreased solute redistribution which occurs in the more rapidly cooled material.
Rapidly Solidified Ti Alloys Containing Metalloids and Rare Earth Metals— Their Microstructure and Mechanical Properties
Authors: Chi C.S. , Whang S.H.
Published: March 2011

Rapidly solidified (RS) Ti alloys containing novel additives were prepared by splat quenching and melt spinning techniques. Microstructures of the as-quenched and heat-treated alloys were studied by electron microscopies. The results show that microstructural refinement and precipitation reaction are universal phenomena in all RS Ti alloys. A significant difference in second phase coarsening was observed between metalloid-origin precipitates and those of rare earth-origin. The precipitates in a Ti-Al-La(Ce) were identified predominantly as rare earth-Al compounds. Exce llent stability for rare earth-origin precipitates was found.

Except for a carbon-containing alloy (700 ° C), age hardening behavior is a universal phenomenon in all RS Ti alloys with additives. A significant strength increase (hardness) in the RS alloy was noted at both room and elevated temperatures.
Thermal Stability of Precipitates in a Rapidly Quenched Ti-Al-Si Alloy
Authors: Wrang S.H. , Lu Y.Z. , Giessen B.C.
Published: March 2011

Ostwald ripening of precipitates in rapidly solidified Ti- 5A1-2Si (wt.%) has been studied by TEM. Results show that particle coarsening at 700 and 800°C is controlled by volume diffusion. Diffusion coefficients of Si in a-Ti were found to be ˜7.5 × 10−13 cm2/sec at 700°C and ˜1.2 × 10−11 cm2 /sec at 800°C.At these temperatures, microstructural refinement due to rapid quenching had no noticeable effect on the coarsening mechanism for the RS Ti-5A1-2Si alloy.
Rapidly Solidified Microstructures in a Ti-22 Wt% Fe Alloy
Authors: Baeslack III W. A. , Weeter L. , Krishnamurthy S. , Smith P. , Froes F. H.
Published: March 2011

Rapidly-solidified microstructures were produced in aTi-22 wt% Fe alloy by laser surface melting, melt extraction, melt spinning and splat cooling. Increased cooling rates during solidification promoted increasingly finer beta grain sizes ranging from approximately 75 microns in a laser melt to 0.5 to 2.0 microns for splats. Beta grain morphologiesw ere generally equiaxed, although epitaxially-nucleated columnar grains were observed at the pool-substrate interface for laser melts. Fitting of the equiaxed beta grain size data to a λ0 = Boε−n0 power relationship for homogenous nucleation and isotropic growth resulted in Bo = 3 × 104 and no = 0.62. The refinement of dendrite structure with increasing cooling rate was also documented for laser melts. Dendrite spacing versus cooling rate data were fitted to a similar general power relationship and resulted in B1 = 45 and n1 = 0.34.
Mechanical Properties of Nickel Base Metastable Solid Solutions with Large Size Mismatch
Authors: Tsai C.L. , Giessen B.C.
Published: March 2011

Ni-based stable and metastable solid solutions with T3 and T4 transition metals have been prepared by rapid liquid quenching. The microhardnesses of these alloys show a substantial increase (by a factor of 4 to 5) that scales with their size mismatch as well as the solute concentration. It was found that the microhardness increase, ΔH, can be fitted well to the theoretical equation: ΔHv = K μ (cη)4/v3 where μ is the solvent shear modulus, c is the solute concentration and η is the size mismatch. The constant K for Ni base solid solutions is ~85.
Glass Forming Ability in Transition Metal Films at 1010 K/s
Authors: Von Allmen M. , Affolter K.
Published: March 2011

Glass formation by ns and ps laser quenching is investigated for the systems Au-Ti, Co-Ti, Cr-Ti and Zr-Ti. Glassy phases are found in all but the last system. These results (as well as earlier ones) show little correlation with published rules to predict glass forming ability, but are consistent with the kinetic analysis presented. Simple Physical parameters related to glass forming ability are discussed. Comparison with results for Cr-Ti allows a determination of the nucleation time-lag.
Microroughness at the Si/SiO2 Interface from Pre-Oxidation Annealing, Measured Using Quantum Oscillations in Fowler-Nordheim Tunneling Currents
Authors: Poler J. C. , McKay K. K. , Irene E. A.
Published: March 2011

As design rules shrink to conform with ULSI device dimensions, gate dielectrics for MOSFET structures are required to be scaled to even thinner proportions. Upon scaling the gate oxides below ∼60Å some properties of the device, such as interface roughness, that are negligible for thicker films become critical and must be evaluated. Microroughness at the interface of ultrathin MOS capacitors has been shown to degrade these devices.

We are studying the interfacial region of ∼50Å SiO2 on Si using the quantum oscillations in Fowler-Nordheim tunneling currents. The oscillations are sensitive to the electron potential and abruptness of the film and its interfaces. In particular, inelastic scattering and/or thickness inhomogeneities in the film will reduce the amplitude of the oscillations. We are using the amplitude of the oscillations to examine the degree of microroughness at the interface that results from a pre-oxidation high temperature anneal in an inert ambient containing various amounts of H2O. Preliminary AFM imaging has shown correlations supporting our microroughness interpretation of the quantum oscillation amplitudes.
Afm Studies of Surface Roughness of Borophosphosilicate Glass (BPSG) Films and Their Impact on Defect Detection Capability for Sub Micron Vlsi Technology
Authors: Rojhantalab H. , Moinpour M. , Peter N. , Dass M.L.A. , Hough W. , Natter R. , Moghadam F.
Published: March 2011

Chemically vapor deposited borophosphosilicate glass (BPSG) has been widely used in microelectronic device fabrication as interlayer dielectric film due to its excellent planarization, gettering and flow properties. With device geometry reducing to sub micron levels, there is an increasingly greater emphasis on detection and elimination of sub micron defects particularly on deposited film. In this paper, we report on the evaluation and characterization of the surface roughness of BPSG films of various thicknesses and film compositions deposited on Si substrates using the Atomic Force Microscopy (AFM). The effects of high temperature densification process on the surface roughness are presented. The defect detection capabilities of conventional laser-based particle counters with respect to the surface roughness of BPSG films are investigated.
A Tem Study of Step Morphology on the Non-Uhv Heat-Treated MgO (100) Surface
Authors: King Simon , Barry Carter C.
Published: March 2011

Preliminary results from a study of the morphology of the MgO (100) surface after chemical etching followed by heat-treatment in air are presented. Contrast arising from the surface-steps so formed is found to be strongly dependent on the deviation parameter, suggesting that many of the step-faces are not perpendicular to the (100) foil plane but are, instead, often rather shallowly inclined.
A Theoretical Study of Amorphous-Crystalline Transition in Si [111] MBE Growth
Authors: Venkatasubramanian R. , Dorsey Donald L. , Das S. G.
Published: March 2011

The amorphous crystalline transition temperature for Si MBE growth is higher for [111] growth than for [100] growth. The mechanism for the growth of amorphous Si in [111] growth is thought to be due to the possibility of of direct formation of stacking faults on the [111] surface. To investigate this mechanism, a kinetic model describing the amorphous-crystalline transition in low temperature Si [111] MBE growth is proposed. The model allows Si atoms to incorporate at three types of sites: A, B and C where A is the triply covalent bonded correct diamond site, B is the triply covalent bonded wrong hep site and C is the singly covalent bonded wrong site. The model allows for the migration of atoms from a wrong site to a nearest neighbor correct site through Arrhenius type rate equations. The migration from B → A is assumed 1000 times weaker than the reverse migration process. Similarly migrations from C → A are assumed 106 time stronger than the reverse migration. All possible migrations are considered with different rates. At the high temperature, the model will allow the growth of a perfect diamond cubic structure with correct ordering of layers AaBbCc etc. A stochastic model describing the above kinetic model is developed based on the master equation approach and random distribution approximation. The low temperature MBE growth of Si [111] is investigated using this model. The results of the model are compared with existing experimental work [1]. The results are in good agreement. The study shows that the kinetics of the site correcting migration process well describes the observed amorphous-crystalline transition in [111] Si MBE growth.
Interface Formation and Thin Film Properties of an Incompatible Polymer System
Authors: Guckenbiehl B. , Stamm M. , Springer T.
Published: March 2011

The polymer blend system of deuterated polystyrene (PSd) and the statistical copolymer poly(styrene-co-para-bromo-styrene) (PBrxS) is partially compatible or incompatible depending on the degree of bromination x. The width of the interface in a bilayer system can thus be controlled in a wide range by an adjustment of x. This is demonstrated in neutron reflectivity experiments where the interfacial width is measured with an accuracy better than lnm. The interface width depends strongly on compatibility as expressed by the Flory-Huggins interaction parameter x- Results are compared with current theories.
Ge Segregation and Surface Roughening During Si Growth on Ge(001)2×l by Gas-Source Molecular Beam Epitaxy from Si2H6
Authors: Tsu R. , Lin D.-S. , Greene J. E. , Chiang T.-C.
Published: March 2011

Surface morphological and compositional evolution during the initial stages of Si growth on Ge(001)2×1 by cyclic gas-source molecular-beam epitaxy (GSMBE) from Si2H6 has been investigated using in-situ reflection high-energy electron diffraction (RHEED), Auger electron spectroscopy (AES), electron energy-loss spectroscopy (EELS), and scanning tunneling microscopy (STM). At 550 °C, single-step-height island growth was observed for nominal Si deposition thicknesses tsi up to ≃ 1.5 ML. The islands were essentially pure Ge which segregated to the surface as H was desorbed. At higher tsi, the Ge coverage decreased, the surface roughened, and two-dimensional multi-layer island growth was observed for tSi up to ≃8 ML above which three-dimensional island growth was obtained. For thick layers (t S: 75 ML), no Ge was detected at the surface.
Orientational and Microstructural Evolution During Epitaxial Growth of Cu on Si(001) by Sputter Deposition
Authors: Hashim I. , Park B. , Atwater H. A.
Published: March 2011

Epitaxial Cu thin films have been grown on H-terminated Si(OOl) substrates at room temperature by D.C. ion-beam sputter deposition in ultrahigh vacuum. The development of orientation and microstructure during epitaxial growth from the initial stages of Cu growth up to Cu thicknesses of few hundred nm has been investigated. Analysis by in-situ reflection high energy electron diffraction, thin film x-ray diffraction, and plan-view and cross-sectional transmission electron microscopy indicates that the films are well textured with Cu(001)∥ Si(001) and Cu[100]∥ Si[110]. Interestingly, it is found that a distribution of orientations occurs at the early stages of Cu epitaxy on Si(001) surface, and that a (001) texture emerges gradually with increasing Cu thickness. The effect of silicide formation and deposition conditions on the crystalline quality of Cu epitaxy is also discussed.
Epitaxial Influence of Textured Conducting Metal Oxide Templates on Electrodeposited Ag(Ag3O4)2N03
Authors: Breyfogle Bryan E. , Phillips Richard J.
Published: March 2011

The conducting oxysalt Ag(Ag3O4)2NO3 has been electrodeposited onto highly oriented conducting oxides of Tl2 03 and Pb0.8Tl0.2O1.9. T12O3 was grown in a [100] texture while the Pb0.8Tl0.2O1.9 was grown with two different thickness-dependent textures of [110] and [210]. The orientation of the Ag(Ag3O4)2NO3 crystals with respect to the substrate surface was determined by x-ray diffraction. The face-centered-cubic Ag(Ag3O4)2N03 crystals deposited on body-centered-cubic T12 03 and face-centered-cubic Pb0.8Tl0.2O1.9 followed the orientation of these prelayers. However, Ag(Ag3O4)2N03 which was electrodeposited onto polycrystalline 430 stainless steel had a nearly random orientation. The lattice mismatch is 6.6% between T12 03 and Ag(Ag3O4)2N03, and it is 7.8% between Ag(Ag3O4)2N03 and the doubled unit cell of Pb0.8Tl0.2Ol.9.
Defect Anisotropy in Movpe CdTe/GaAs
Authors: Cheng T. T. , Aindow M. , Jones I. P. , Hails J. E. , Williams D. J. , Astles M. G.
Published: March 2011

A cross-sectional TEM study of the defect structure in CdTe buffer layers grown on 2°-off (001) GaAs substrates by MOVPE is presented. The nature and distribution of defects in the buffer layers are shown to be highly anisotropic. Images obtained with the beam direction parallel to [110] show that high densities of stacking faults are present on one of the two equivalent (111} planes, whereas those obtained with the beam direction parallel to [110] show subgrain boundaries perpendicular to the interface. HREM images of the interfacial region along these two directions show a pronounced difference in the character of the misfit dislocations with b = a/2 <110>. Those with line directions parallel to [110] are all edge (90°) dislocations whilst the orthogonal set are an intimate mixture of edge and mixed character (60°) dislocations. This anisotropy is attributed to the combined effects of substrate off-cut and the formation of high aspect ratio island nuclei, giving differences in misfit accommodation.