bluuebunny/crossref_metadata_2025_split huggingface dataset:
Growth of BaTiO3 Thin Films by MOCVD
Authors: Kaiser Debra L. , Vaudin Mark D. , Gillen Greg , Hwang Cheol-Seong , Robins Lawrence H. , Roiter Lawrence D. 
Published: March 2011

AbstractPolycrystalline thin films of BaTiO3 were deposited on fused quartz substrates at 600°C by metalorganic chemical vapor deposition (MOCVD). The films were characterized by x-ray powder diffraction (XRD), transmission electron microscopy (TEM), secondary ion mass spectroscopy (SIMS) and Raman spectroscopy. Films prepared in the early stages of this study that had appeared to contain only crystalline BaTiO3 by XRD were found to have nonuniform composition and microstructure through the film thickness by SIMS and TEM. The MOCVD system was then modified by installing a process gas bypass apparatus and an elevated pressure bubbler for the titanium isopropoxide precursor. A 1.2 μm thick BaTiO3 film prepared in the modified system demonstrated much improved compositional and microstructural uniformity through the thickness of the film. This film had a columnar microstructure with grain widths of 0.1–0.2 μm and exhibited tetragonality as detected by Raman spectroscopy.
Deposition of Dielectric Thin Films by Irradiation of Condensed Reactant Mixtures
Authors: Moore J. F. , Strongin D. R. , Ruckman M. W. , Strongin M. 
Published: March 2011

AbstractResults of ongoing investigations of a new method for processing molecular solids to form refractory thin films are presented. We have extended past work on boron nitride and alumina growth from molecular solids induced by synchrotron radiation (SR), to silica growth from tetramethylsilane and water at 80 K. Also reported are experiments where alumina is formed using 4.64 eV laser irradiation. The majority of the results suggest that with SR, the film growth is induced by secondary electrons from the substrate, whereas laser light excites the film growth by direct photolysis. Implications of this will be discussed.
Influence of SiC Additions on the Microstructure of Gray Cast Iron
Authors: Schubert W. D. , Ta A. T. , Kahr G. , Benecke Th. , Lux B. 
Published: March 2011

ABSTRACTThe influence of additions of different SiC grades on the solidification of hypoeutectic and eutectic gray cast iron has been studied and compared with the additions of “FeSi 75” and pure silicon.It is shown that additions of SiC change undercooling, microstructure as well as graphite shape and distribution in cast iron melts in a different manner than either FeSi or pure Si do. The difference is explained by the special dissolution kinetics of SiC which leads to formation of graphite and a lonqer-lastirg influence of carbon agglomerates in the melt. It is shown that SiC grades which are partially protected by SiO2 films from rapid dissolution in the iron melt show the most pronounced effect.From the laboratory experiments it can be concluded that melt additions of special SiC grades can modify the microstructure of gray cast iron. A-graphite is more evenly distributed and formation of the Fe/Fe3C eutectic is more difficult. Similar influences are known from industrial production and can now be partially explained.
Structure and Formation of Vermicular Graphite
Authors: Xijun Den , Peiyue Zhu , Gifu Liu 
Published: March 2011

ABSTRACTUsing both liquid quenching and SEM technique is found that the vermicular graphite (CVG ) is formed Mainly in two ways. First, it grows out from flake graphite, and second, it degenerates, from spheroidal graphite (SC).According to this, two models of morphology and formation process.of CVS are sugguted. It. is discovered that the qrowth.direction of CVG of ten changes from a-to c-direction, or vice versa. Because of thu influence of modifying elements, the CVG is. twistad sq-verely, changing its growth direction continually and branching frequently. The growth of the branches may be in a-and/or c-direction; and their tips may be round and/or sharp. In all cases, there exists a large fraction of thick flake graphithe in the vermicular graphite. It is Suggested that the redistribution of modifying elements plays an importeant role in the formatinn of CVG.
Computer Simulation of Solidification of Nodular Cast Iron
Authors: Su Kou-Chang , Ohnaka Itsuo , Yamauchi Isamu , Fukusako Tatsuichi 
Published: March 2011

ABSTRACTSolidification of a nodular iron casting was simulated by an undercooling nucleation and diffusion controlled growth model. Simulated cooling curves were similar to measured ones but estimating nodular size distribution requires improving the model.
Further use of Secondary Ion Mass Spectrometry in the Study of Graphite Morphology Control TN Cast Irons
Authors: Franklin S. E. , Stark R. A. 
Published: March 2011

ABSTRACTIn a previous publication, preliminary results obtained using secondary ion mass spectrometry to determine selective elemental distributions in cast iron were reported. These results were used to tentatively assign possible roles to the important solutes in controlling the graphite morphology. The current paper is a continuation of this work and presents the most recent results of the SIMS analysis.
Transition from Grey to White and White to Grey in Fe-C-X Eutectic Alloys
Authors: Magnin P. , Kurz W. 
Published: March 2011

ABSTRACTThe effect of small additions of Si, P, Cr, Mn and Ti on transition velocities from grey to white and white to grey of pure Fe-C eutectics has been measured by varying growth rates in directional solidification experiments. Growth undercoolings were measured as a function of growth rate, while white and grey eutectic temperatures were obtained from DTA experiments. As a result of these experiments, alloying elements can be classified into three categories : graphitizing (Si, P), carburizing (Cr) and “opposite effect” (Mn, Ti). Each category is characterized by a given influence on eutectic temperature, growth undercooling, and nucleation of cementite. A qualitative model which permits determination of the influence of alloying elements on these latter three parameters is proposed.
Kinetics of Graphitization of White Cast Iron
Authors: Takahashi Ryoji 
Published: March 2011

ABSTRACTIt is well known that the gaseous elements have detrimental effects on the annealability of white cast iron for malleablizing. The present knowledge, however, is based on the white cast iron containing about 1.0 % Si. Therefore the author made a series of experiments by using the white east irons with silicon content ranging from 1.0 % to 1.8 %, and carr ied out multiple regression analyses of the measurements. The statistically meaningsful results can be summarized as follows:1) In the silicon range of 1. 01 ∼ 1. 60%, the first stage graphitization is retarded by the soluble nitrogen. However, when silicon exceeds 1. 6 %, the opposite is true.2) In the silicon range of 1. 01 ∼ 1. 40 %, the second stage graphitization is retarded by the soluble nitrogen. The degree of' the retardation increases as the specimens contain less silicon. When more than 1. 40 % Si is present, the second stage graphitization proceeds independently of soluble nitrogen content.3) Oxygen does not at. all influence the first stage graphitization, while the second stage graphitization is slightly retarded by oxygen. This is due to nodule count, which decreases as oxygen content increases.
Effect of Nickel and Aluminium on Solid State Transformations in SG Iron
Authors: Ganguli A. C. , Chakrabarti A. K. , Dasgupta S. C. 
Published: March 2011

ABSTRACTThe individual and combined addition of nickel and aluminium to S.g. iron influences several solid state transformations. Nickel depresses the temperature range for reversion of ferrite and pearlite to austenite on heating, while aluminium raises it. Combined addition of nickel and aluminium restores the temperature range closer to that for unalloyed iron. But nickel enhances the kinetics of ferritisation during tempering and weakly retards recrystallisation of ferrite grains. Aluminium strongly retards both the ferritisation and recrystallisation processes. Ferritisation kinetics is enhanced and recrystallisation of ferrite grains is also hastened in alloys containing nickel and aluminium. Alloys containing nickel and aluminium also respond to agehardening treatment in the temperature range 450–550°C after a solution treatment-cum-ferritising anneal at 700°C. On the basis of X-ray diffraction and electron microscopic studies, a probable mechanism of ageing has been proposed.
Influences of Silicon and Phosphorus Contents and Cooling Rate on JIC Fracture Toughness of Ferritic Spheroidal Graphite Cast Iron
Authors: Komatsu Shinichiro , Shiota Toshio 
Published: March 2011

ABSTRACTThe influences of silicon and phosphorus contents and cooling rate on JIC fracture toughness of ferritic spheroidal graphite cast iron were investigated by 15mm thick compact tension test-pieces. The JIC values were measured by means of the R-curve method for most cases at 20°C, and by means of the maximum J value method for the cases at -100° C. The results obtained are summarized as follows. At 20WC, the specimens with silicon contents less than 3.2% showed the ductile Load-COD relations, but a specimen with 3.5%Si showed a brittle Load-COD relation and the JIC decreased greatly. Increasing phosphorus content between 0.006% and 0.26% made the JIC value decrease gradually and made the slope of the R-curve decrease greatly. Difference in cooling rate produced differences in graphite nodule diameters and ferrite grain sizes. At 20°C, the larger the specimen's average graphite nodule diameter was, the larger the JIC value was. At -100° C, the Jic values of all the specimens tested decreased largely, and the influences of these factors became very different from those at 20° C.
Influence of Trace Elemients Oh Graphite Forms in Cast Iron
Authors: Bhavsar R. D. , Blake N. W. , Ghoreshy B. , Smith T. W. 
Published: March 2011

ABSTRACTSynthetic and commercial Fe-C-Si irons have been frozen under controlled conditions after vacuum purification in order to correlate graphite forms with freezing conditions and alloy composition. It was found that graphite morphology was influenced prirmarily by the sulphur and oxygen contents and the rate of cooling. The various modes of graphite growth are discussed, particularly the appearance of the coral and compacted graphite surfaces at high magnification after the addition of oxygen or nitrogen.
The Physical Chemistry of Inoculation of Cast Iron
Authors: Gadd M. A. , Bennett G. H. J. 
Published: March 2011

ABSTRACTA theoretical analysis of inoculation shows that homogeneous nucleation of CaO, CaS, Al2O3and ZrO2is possible arid subsequent heterogeneous nucleation of silicates yields substrates for graphite growth. Excessive silicate growth leading to separation of nuclei could result in fade.Results show that CaO/CaS embyros are most effective via silicate formation, Zr and Al control fade arido xidation enhances inoculation and fade. Added stable oxides give only limited inoculation.
Time-Resolved X-Ray Studies During Pulsed-Laser Irradiation of
Ge
Authors: Tischler J.Z. , Larson B.C. , Mills D.M. 
Published: March 2011

ABSTRACTSynchrotron x-ray pulses from the Cornell High Energy Synchrotron Source
(CHESS) have been used to carry out nanosecond resolution measurements of
the temperature distrubutions in Ge during UV pulsed-laser irradiation. KrF
(249 nm) laser pulses of 25 ns FWHM with an energy density of 0.6 J/cm2 were
used. The temperatures were determined from x-ray Bragg profile measurements
of thermal expansion induced strain on <111> oriented Ge. The data
indicate the presence of a liquid-solid interface near the melting point,
and large (1500-4500°C/pm) temperature gradients in the solid; these Ge
results are analagous to previous ones for Si. The measured temperature
distributions are compared with those obtained from heat flow calculations,
and the overheating and undercooling of the interface relative to the
equilibrium melting point are discussed.
Ultrafast Phase Transition of GaAs Surfaces Irradiated by
Picosecond Laser Pulses
Authors: Liu J.M. , Malvezzi A.M. , Bloembergen N. 
Published: March 2011

ABSTRACTDetailed analysis of the second harmonic signals in reflection from
crystalline GaAs surfaces reveals that the structural transition associated
with surface melting occurs in less than 2 ps. Preliminary results of
picosecond time-resolved reflectivity measurements are also presented.
Effects of Arsenic Doping on the Solidification Dynamics of
Pulsed-Laser-Melted Silicon
Authors: Thompson Michael O. , Peercy P. S. , Tsao J. Y. 
Published: March 2011

ABSTRACTThe effects of arsenic doping on the solidification dynamics during pulsed
melting of silicon have been studied using the transient conductance
technique. At As concentrations below 1 at.%, the incorporation of As into
the Si lattice results in negligible differences in the solidification
dynamics. Between 2 and 7 at.% As, however, the interface velocity is
dramatically modified as the liquid-solid interface crosses the As
containing region. These velocity changes are consistent with a reduced
melting temperature for Si-As alloys. For concentrations of 11 at.% As, the
depression in the melting temperature is sufficient to allow the surface to
solidify while considerable melt remains buried within the sample. At 16
at.%, the melting temperature is drastically reduced and internal nucleation
of melt occurs prior to normal surface melting.
Effects of Impurities on the Competition between Solid Phase
Epitaxy and Random Crystallization In Ion-Implanted Silicon
Authors: Olson G.L. , Roth J.A. , Rytz-Froidevaux Y. , Narayan J. 
Published: March 2011

ABSTRACTThe temperature dependent competition between solid phase epitaxy and random
crystallization in ion-implanted (As+, B+,
F+, and BF2+) silicon films is investigated. Measurements of time-resolved
reflectivity during cw laser heating show that in the As+,
F+, and BF2+-implanted layers (conc 4×1020cm-3)
epitaxial growth is disrupted at temperatures 1000°C. This effect is not
observed in intrinsic films or in the B+-implanted layers.
Correlation with results of microstructural analyses and computer simulation
of the reflectivity experiment indicates that disruption of epitaxy is
caused by enhancement of the random crystallization rate by arsenic and
fluorine. Kinetics parameters for the enhanced crystallization process are
determined; results are interpreted in terms of impurity-catalyzed
nucleation during the random crystallization process.
Raman Measurements on Graphite Modified by High Power Laser
Irradiation
Authors: Steinbeck J. , Braunstein G. , Dresselhaus M.S. , Elman B.S. , Venkatesan T. 
Published: March 2011

AbstractThe behavior of highly anisotropic materials under short pulses of high
power laser irradiation has been studied by irradiating highly oriented
pyrolytic graphite (HOPG) with 30 nsec Ruby-laser pulses with energy
densities between 0.1 and 5.0J/cm2. Raman spectroscopy has been
used to investigate the laser-induced modifications to the crystalline
structure as a function of laser energy density of the laser pulse. A Raman
microprobe was used to investigate the spatial variations of these
near-surface regions. The irradiation of HOPG with energy densities above ~
0.6J/cm2 leads to the appearance of the ~ 1360 cm-1
disorder-induced line in the first order Raman spectrum. The intensity of
the ~ 1360cm-1 line increases with increasing laser energy
density. As the energy density of the laser pulse reaches about
1.0J/cm2, the ~ 1360cm-1 line and the ~
1580cm-1 Raman-allowed mode broaden and coalesce into a broad
asymmetric band, indicating the formation of a highly disordered region,
consistent with RBS-channeling measurements. However, as the laser energy
density of the laser pulses is further increased above 3.0J/cm2,
the two Raman lines narrow and can again be resolved suggesting
laser-induced crystallization. The Raman results are consistent with high
resolution electron microscopy observations showing the formation of
randomly oriented crystallites. Raman Microprobe spectra revealed three
separate regions of behavior: (i) an outer unirradiated region where the
material appears HOPG-like with a thin layer of material coating the
surface, (ii) an inner irradiated region where the structure is uniform, but
disordered, and (iii) an intermediate region between the other regions where
the structure is highly disordered. The changes in structure of the inner
region are consistent with the behavior observed with RBS and conventional
Raman spectra. The identification of an amorphous carbon-like layer on the
outer region is consistent with a large thermomechanical stress at the
graphite surface, introduced by the high power laser pulse, and known to
occur in metals.
Calculations on Multi-Pulse, Laser-Induced Diffusion and
Evaporation Loss of Arsenic and Boron in Silicon
Authors: Tan H.S. , Ong C.K. 
Published: March 2011

ABSTRACTA dopant redistribution model that has the dopant diffusion equation
partially solved analytically before engaging numerical method in its final
solution was formulated. The model which included an evaporation loss
mechanism for the near-surface dopants was then employed in the theoretical
fitting of the measured As and ? redistributed profiles in Si due to single
and ten-pulse laser irradiations. All the dopant profiles computed were in
good agreement with the measured SIMS data. The values of dopant diffusion
coefficients Dℓ in liquid Si that were deduced presently from the
dopant profile fitting were (3.2 00B1 0.3) ×
10-4-cm2s-1 for As and (4.0 00B1 0.4) ×
10-4-cm2s-1 for ? respectively.
Comparison to the reported experimental values of Dℓ was also
made.
A Study of Electrically Active Defects Induced by Pulsed
Electron Beam Annealing In (100) N-Type Virgin Silicon
Authors: Doghmane M.S. , Barbier D. , Laugier A. 
Published: March 2011

ABSTRACTAu/Si Schottky contacts have been used as test structures to investigate
defects induced in virgin C.Z (100) N-type silicon after irradiation with a
12 to 20 KeV mean energy electron beam pulse. A thin and highly damaged
surface layer was observed from a fluence threshold of 1 J/cm2.
In addition electron traps were detected in the PEBA induced melting layer
with concentrations in the 1012-1013 cm-3
range. Their depth profiles have been related to the PEBA induced melting
layer thickness. Quenching of multidefect complexes is the most probable
mechanism for electron trap generation in the processed layer.
Strain/Damage in Crystalline Materials Bombarded by MeV Ions: Recrystallization of GaAs by High-Dose Irradiation
Authors: Wie C. R. , Vreeland T. , Tombrello T. A. 
Published: March 2011

ABSTRACTMeV ion irradiation effects on semiconductor crystals, GaAs(100) and Si (111) and on an insulating crystal CaF2(111) have been studied by the x-ray rocking curve technique using a double crystal x-ray diffractometer. The results on GaAs are particularly interesting. The strain developed by ion irradiation in the surface layers of GaAs (100) saturates to a certain level after a high dose irradiation (typically 1015/cm2), resulting in a uniform lattice spacing about 0.4% larger than the original spacing of the lattice planes parallel to the surface. The layer of uniform strain corresponds in depth to the region where electronic energy loss is dominant over nuclear collision energy loss. The saturated strain level is the same for both p-type and n-type GaAs. In the early stages of irradiation, the strain induced in the surface is shown to be proportional to the nuclear stopping power at the surface and is independent of electronic stopping power. The strain saturation phenomenon in GaAs is discussed in terms of point defect saturation in the surface layer.An isochronal (15 min.) annealing was done on the Cr-doped GaAs at temperatures between 200° C and 700° C. The intensity in the diffraction peak from the surface strained layer jumps at 200° C < T ≤ 300° C. The strain decreases gradually with temperature, approaching zero at T ≤ 500° C.The strain saturation phenomenon does not occur in the irradiated Si. The strain induced in Si is generally very low (less than 0.06%) and is interpreted to be mostly in the layers adjacent to the maximum nuclear stopping region, with zero strain in the surface layer. The data on CaF2have been analysed with a kinematical x-ray diffraction theory to get quantitative strain and damage depth profiles for several different doses.
High-Quality Boron and BF2+-Implanted P+ Junctions in Si Using Solid Phase
Epitaxy and Transient Annealing
Authors: Vasudev P.K. , Schmitz A.E. , Olson G.L. 
Published: March 2011

ABSTRACTWe report on a systematic study of the doping profiles resulting from rapid
thermal annealing of boron and BF2+-implanted silicon samples that were preamorphized by
Si+ implantation. A two-step process consisting of an initial
solid phase epitaxial regrowth followed by a brief (~5 sec) high temperature
(1050ଌ) anneal produces extremely shallow (<1500Å) junctions with low
defect concentrations. The quality of the epitaxial regrowth is very
sensitive to implant conditions and impurity effects as deduced from
time-resolved reflectivity measurements. Using the best conditions for
implantation and solid phase crystallization, we have obtained boron-doped
regions with sheet resistivities of 40 Ω/ and BF2-doped regions
of resistivity 60 Ω/.
Pulsed-CO2-Laser Annealing of Ion-Implanted
Silicon
Authors: James R.B. , Narayan J. , Christie W.H. , Eby R.E. , Holland O.W. , Wood R.F. 
Published: March 2011

AbstractFrom studies of time-resolved reflectivity and microstructural changes, we
have obtained direct evidence of CO2 laser-induced melting above
a threshold energy density. Results of the optical measurements,
transmission electron microscopy, and secondary ion mass spectrometry are
reported. The measurements show that melt depths as deep as 1 μm can be
achieved with pulsed CO2 laser radiation. By using differential
absorption between layers with different free-carrier densities, we find
that a CO2 laser can be used to melt regions which are embedded
in the material. It is likely that this observed phenomenon is impossible to
obtain with a visible or ultraviolet laser.
Rapid Annealing of GaAs and Related Compounds
Authors: Williams J.S. , Pearton S.J. 
Published: March 2011

ABSTRACTIn recent years, rapid annealing of GaAs has been employed to activate ion
implanted dopants and to produce metal-semiconductor contacts. More
recently, rapid heating techniques have been used to anneal heterostructures
without degrading requisite high mobilities of SDHT devices. This paper
reviews the various annealing regimes which are useful for heat treating
GaAs and related compounds. Examples are chosen which illustrate unique and
potentially useful features of rapid annealing.
Analysis of High Dose Implanted Silicon by High Depth Resolution
Rbs and Spectroscopic Ellipsometry and TEM
Authors: Lohner T. , Mezey G. , Fried M. , GhiţA L. , Ghiţa C. , Mertens A. , Kerkow H. , Kctai E. , PÁSzti F. , BÁNyai F. , VÍZkelethy GY. , JÁRoli E. , Gyulai J. , Somogyi M. 
Published: March 2011

ABSTRACTOne of the applications of high dose ion implantation is to form surface
alloys or compound layers. The detailed characterization of such composite
structures is of great importance. This paper tries to answer the question:
how can we outline, at least, a qualitative picture from the optical
properties measured by ellipsometry of high dose Al and Sb implanted
silicon. Attempts are done to separate the effect of implanted impurities
from the dominant disorder contribution to the measured optical properties.
As the ellipsometry does not provide information enough to decide the
applicability of optical models therefore methods sensitive to the structure
(channeling and TEM) were applied too.