bluuebunny/crossref_metadata_2025 huggingface dataset:
The Influence of In-Grown Stacking Faults on the Reverse Current-Voltage Characteristics of 4H-SiC Schottky Barrier Diodes
Authors: Harada Shin , Namikawa Yasuo
Published: March 2009

The area where 4H-SiC SBDs showed high reverse currents was extracted. After KOH
etching, the in-grown SF on the basal plane, composed of a straight etch line with a pair of tilted oval
pits and additional etch pits forming an isosceles triangle, was observed on some devices. All of the
devices containing this SF structure showed large reverse leakage currents in spite of the good
forward I-V characteristics. We speculate that this in-grown SF includes another planar fault on the
{1-100} plane besides the basal plane which has a great influence on reverse currents of SBDs.
Behaviour of 4H-SiC pin Diodes Studied by Numerical Device Simulation
Authors: Werber Dorothea , Borthen P. , Wachutka Gerhard
Published: March 2009

We simulated and measured the forward characteristics of 4H-SiC pin diodes in a wide
temperature range from 300K to 700K. Our simulations are based on the stationary drift-diffusion
model including a model for incomplete ionization of the dopants. Physically based models for
Auger recombination and Shockley-Read-Hall recombination are used as well. For the mobility
model the empirical relation of Caughey-Thomas is used. The model parameters to be calibrated in
the simulation are the electron and hole minority lifetimes and the electron and hole bulk mobilities.
Employing temperature-dependent carrier lifetimes we achieved very good agreement between
simulations and measured data. For the temperature- and doping-dependent carrier mobilities we
found that the best fit is obtained for a bulk mobility value much smaller than that suggested by
standard parameters for 4H-SiC. With the calibrated parameters we simulated the internal carrier
distributions for temperatures up to 700 K and for different carrier lifetimes.
Evaluation of Termination Techniques for 4H-SiC Pin Diodes and Trench JFETs
Authors: Mihaila Andrej , Udrea F. , Rashid S.J. , Amaratunga G. , Kataoka Mitsuhiro , Takeuchi Yuuichi , Malhan Rajesh Kumar
Published: March 2009

An investigation concerning suitable termination techniques for 4H-SiC trench JFETs is
presented. Field plates, p+ floating rings and junction termination extension techniques are used to
terminate 1.2kV class PiN diodes. The fabricated PiN diodes evaluated here have a similar design to
trench JFETs. Therefore, the conclusions for PiN diodes can be applied to JFET structures as well.
Numerical simulations are also used to illustrate the effect of the terminations on the diodes’
blocking mode behaviour.
Fabrication of pn-Junction Diode for N+ Implanted 4H-SiC(0001) Annealed by EBAS
Authors: Egami Akihiro , Shibagaki Masami , Kumagai Akira , Numajiri Kenji , Miyagawa Shingo , Kudo Takahiro , Uchiumi Satoshi , Satoh Masataka
Published: March 2009

We fabricate pn-junction diode on p-type 4H-SiC(0001), in which n-type region is formed
by N ion implantation at room temperature (total dose: 2.4 x 1015 /cm2, thickness: 300 nm) and
subsequently annealed for 5 min using electron bombardment annealing system (EBAS). The
root-mean-square (RMS) surface roughness and sheet resistance (Rs) for N ion implanted region,
annealed at 1900 oC is estimated to be 0.7 nm and 940 4/sq., respectively. The alloyed Ni ohmic
contact to N ion implanted layer, annealed at 1900 oC, shows the contact resistance (Rc) of
8.3 x 10-5 4cm2. The forward drop voltage at 100 A/cm2 and on-resistance of mesa-type pn junction
diode is estimated to be 3.1 V and 1.3x10-2 4cm2. The reverse bias leakage current of that is
2.2 x 10-5 A/cm2 at 100 V. It is demonstrated that EBAS is able to apply for the fabrication of
pn-junction diode.
Microwave p-i-n Diodes Fabricated on 4H-SiC Material Grown by Sublimation Epitaxy in Vacuum
Authors: Camara Nicolas , Romanov L.P. , Kirillov A.V. , Boltovets Mykola S. , Lebedev Alexander A. , Zelenin V.V. , Kayambaki M. , Zekentes Konstantinos
Published: March 2009

4H-SiC p-i-n diodes were fabricated on epitaxial layers grown by Sublimation Epitaxy in
Vacuum (SEV) and were evaluated for microwave power switching applications. Full electrical
characterization (C-V, DC I-Vs, reverse recovery characteristics, low and high power microwave
testing) has been performed. The results showed that SEV-grown SiC material is suitable for
bipolar device fabrication. A doping higher than 1019 cm-3 for the p-type contact layer and lower
than 1016 cm-3 for the n-type base layer is necessary to demonstrate microwave p-i-n diodes with
similar performance as the ones fabricated on commercially available CVD-grown material.
Fabrication and Test of 3C-SiC Electrostatic Resonators
Authors: Placidi Marcel , Godignon Philippe , Esteve Jaume , Mestres Narcis , Abadal Gabriel
Published: March 2009

Silicon Carbide has proven its relevance for various MEMS and sensors devices
applications. This paper presents the fabrication and the first test results of 3C-SiC electrostatic
resonators actuated by applying a combination of AC and DC voltages. The recipe used for the
fabrication has taken the advantage of the starting material, 3C-SiC grown on Si, which allows us to
use the Si substrate as sacrificial layer to release the structures. Resonators have been fabricated by a
two-step process, combining RIE ICP etching with HF wet etching. Resonators have been
successfully electrostatically actuated in air-ambient condition. The resonance frequencies were
clearly identified, although capacitive current created by actuation was not detected.
Study of Dark Currents in 4H-SiC UV APDs with Separate Absorption and Multiplication Regions
Authors: Soloviev Stanislav I. , Cha Ho Young , Grande James , Sandvik Peter M.
Published: March 2009

Avalanche photodiodes (APDs) based on 4H-SiC are excellent candidates to replace
PMTs in the UV, particularly for harsh environment applications. Here, we report on dark current
analysis of 4H-SiC APDs with separate absorption and multiplication regions. Detailed analysis of
the leakage current as a function of device size showed that for a given device design, the bulk
leakage component is dominant at U>600V, while surface leakage is dominant at U<600V. Electron
beam induced current was also used to establish a correlation between leakage current and major
types of defects in the substrate. There were two types of dislocations that could be easily
distinguished in the images, including threading (spots) and basal plane (comet-like) dislocations.
Using image processing software, densities of threading dislocations as well as basal plane
dislocations were obtained and correlated with leakage currents of the corresponding APDs. The
results suggest a strong effect of threading dislocations on dark current. Densities of basal plane
dislocations were very similar in all devices tested suggesting that a role of basal plane dislocations
was not dominant in leakage current of the APDs.
Growth and Photoluminescence Study of Aluminium Doped SiC Epitaxial Layers
Authors: Pedersen Henrik , Henry Anne , ul Hassan Jawad , Bergman Peder , Janzén Erik
Published: March 2009

Epitaxial layers were grown in a horizontal hot-wall CVD reactor and intentionally doped
with aluminium in a wide concentration range by varying the flow of aluminium into the reactor.
The layers were grown on 4H and 6H SiC substrates on both Si and C face. Low temperature
photoluminescence (LTPL) has been used to characterize the layers; 6H-SiC show differences in
the structure of the Al bound-exciton (Al-BE) between the two faces, suggesting that the site
preference is face dependent. From the LTPL spectra the Al concentration in the layers can be
estimated.
Comparison of Bipolar and Unipolar SiC Switching Devices for Very High Power Applications
Authors: Bertilsson Kent , Harris Chris I.
Published: March 2009

Both unipolar and injection SiC devices can be used for high voltage switching
applications; it is not determined, however, for which applications one approach is preferred over
the other. In this paper, simulation studies are used to compare the suitability of unipolar devices, in
this case a JFET (Junction Field Effect Transistor) against an equivalent FCD (Field Controlled
Diode) configuration up to very high voltages. The calculations are performed in a finite element
approach, with commercial drift-diffusion software. Numerous drift layers have been simulated in a
Monte-Carlo approach to ensure that the optimal design of the drift layers for different breakdown is
used. In a static case, purely conductive losses in the drift layer in both unipolar and injection
configuration are compared. Additionally the total losses are studied and compared in switched
applications for different switching frequencies and current levels.
High Temperature Applications Of 4H-SiC Vertical Junction Field-Effect Transistors And Schottky Diodes
Authors: Bhatnagar Praneet , Wright Nicolas G. , Horsfall Alton B. , Johnson C. Mark , Uren Michael J. , Hilton Keith P. , Munday A.G. , Hydes A.J.
Published: March 2009

Silicon Carbide (SiC) power devices are increasingly in demand for operations which
require ambient temperature over 300°C. This paper presents circuit applications of normally-on
SiC VFETs at temperatures exceeding 300°C. A DC-DC boost converter using a 4H-SiC VJFET
and a SiC Schottky Diode was fabricated and operated up to 327°C. A power amplifier achieved a
voltage gain of 3.88 at 27°C dropping to 3.16 at 327°C. This 20 % reduction is consistent with the
fall in transconductance of the device.
High Temperature DC-DC Converter Performance Comparison Using SiC JFETs, BJTs and Si MOSFETs
Authors: Scofield James D. , Kosai Hiroyuki , Jordan Brett , Ryu Sei Hyung , Krishnaswami Sumi , Husna Fatima , Agarwal Anant K.
Published: March 2009

The performance and characterization of SiC JFETs and BJTs, used as inverter switching
devices, in a 2 kW, high temperature, 33 kHz, 270-28 V DC-DC converter has been accomplished.
SiC and Si power devices were characterized in a phase shifted H-bridge converter topology
utilizing novel high temperature powdered ferrite transformer material, high temperature ceramic
filter capacitors, SiC rectifiers, and 10 oz. 220oC polyimide printed circuit boards. The SiC devices
were observed to provide excellent static and dynamic characteristics at temperatures up to 300oC.
SiC JFETs were seen to exhibit on-resistance trends consistent with temperature-mobility kinetics
and temperature invariant dynamic loss characteristics. SiC BJTs exhibited positive temperature
coefficients (TCE) of VCE and negative β TCEs, with only a 2-fold increase in on-resistance at
300oC. Both SiC power devices possessed fast inductive switching characteristics with τon and τoff
~100-150 ns when driving the transformer load. The SiC converter characteristics were compared
to Si-MOSFET H-bridge operation, over its functional temperature range (30-230oC), and highlights
the superiority of SiC device technology for extreme environment power applications.
Grain Growth in Materials with Mobile Second-Phase Particles
Authors: Novikov Vladimir Yu.
Published: March 2009

Grain growth controlled by particles able to move together with grain boundaries is
investigated by means of numerical simulation. The particles either located on grain boundaries or
randomly distributed over the material volume are shown to retard the growth process. In the first
case the growth kinetics is described by a power law Dn −D0
n = kt with the exponent n≤ 3. Growth
kinetics under the influence of randomly distributed mobile particles can be approximated by the
same law with the exponent n increasing with an increase in the particle volume fraction.
Phase-Field Modeling and Simulation of Nucleation and Growth of Recrystallized Grains
Authors: Takaki Tomohiro , Yamanaka A. , Tomita Yoshihiro
Published: March 2009

The novel coupling recrystallization model is proposed in this study. First, the deformation microstructure was simulated by the finite element method based on the strain gradient crystal plasticity theory. The calculated dislocation density and crystal orientation were transferred to the recrystallization phase-field simulation. The initial subgrain structures used in phase-field simulation were determined by a relationship between dislocation density and subgrain size with the dislocation density distribution calculated by crystal plasticity simulation. The so-called KWC phase-field model, which can introduce both subgrain rotation and grain boundary migration, was employed, and spontaneous nucleation and grain growth were simulated simultaneously.
Diffusion Controlled Abnormal Grain Growth in Ceramics
Authors: Dillon Shen J. , Harmer Martin P.
Published: March 2009

The grain growth kinetics of silica and calcia doped alumina at 1400oC and their grain
boundary complexion is characterized. These data are compared to predictions of both diffusion
controlled and nucleation limited interface controlled grain growth theory. It is deduced from the
indicators that the mechanism for normal and abnormal grain growth in these aluminas is diffusion
controlled.
Recrystallization Behavior of Nano Grained Cu-Zn Alloy Produced by Multi-Directional Forging
Authors: Nakao Y. , Miura Hiromi , Sakai Taku
Published: March 2009

The static recrystallization (SRX) behavior of nano grained (NGed) Cu-30mass%Zn alloy processed by Multi-directional forging (MDF) was investigated. The NGed Cu-Zn alloy showed characteristic annealing behavior. The SRX nucleation and its grain growth occurred more readily in the samples deformed to higher cumulative strain at lower temperature. The frequency of new grain formation in the samples MDFed at 77 K was much higher than that at 300 K. The new grains were composed of fine annealing twins with thickness from 10 to 200 nm. The average grain size fully recrystallized was less than 300 nm.
Growth of Cu-Oxide Protrusion by Ar Ion Irradiation
Authors: Tanaka Hiroyuki , Tanaka Shunichiro
Published: March 2009

Cu2O conical micron-scale protrusions have been grown on a preoxidized Cu surface by
the Ar ion beam irradiation at 9 kV for 5-20 min in the low vacuum. This Ar ion irradiation is based
on the ‘Transcription Method’ which has been originated by B.-S. Xu and S.-I. Tanaka in 1996 to
form nanoparticles. Ar ion irradiation induced needle-like nanostructures composed of Cu2O and
CuO which were randomly nucleated on Cu surface by the oxidation at 623 K for 10 min in the air.
The obtained Cu2O conical protrusions have a controllable length of up to 14.6 μm with diameter in
the range of 0.8 μm by changing the Ar ion irradiation angle to the surface. The mechanism of the
formation of the conical protrusions is proposed that Cu atoms on the Cu surface activated and
sputtered by the Ar ion irradiation diffuse on the surface of needle-like oxide as nuclei along the Ar
ion track and react with residual oxygen atoms to grow the conical Cu2O protrusions.
Microstructure - Texture Related Toughness Anisotropy of API-X80 Pipeline Steel Characterized by Means of 3D-EBSD Technique
Authors: Petrov Roumen H. , García Orlando León , Mouriño Nuria Sánchez , Kestens Leo , Bae Jin Ho , Kang Ki Bong
Published: March 2009

The variations of in plane Charpy toughness anisotropy as a function of the microstructure and texture of an industrial grade of API –X80 pipeline steel was studied. Standard size Charpy samples with a long axis orientated at 0, 22.5, 45, 67.5 and 90° with respect to the rolling direction of the plate were tested at different temperatures varying from -196°C to 20°C. Microstructure and texture of the plates were investigated by means of electron backscattering diffraction (EBSD), XRD and the recently developed 3D EBSD technique. The spatial grain shape orientation distribution was examined on samples which were cut from the middle thickness of an industrial rolled plate by means of 3D EBSD and following grain shape reconstruction and approximation of the grain shape with ellipsoids. It was found that the experimentally observed 3D microstructures could well be correlated to the anisotropy of the measured Charpy impact toughness of the steel for the Charpy samples. The Charpy toughness anisotropy of the plates in the transition region where both ductile and brittle fractures take place can be related to the microstructural anisotropy characterized by the grain shape orientation and the spatial distribution of the 2nd phase.
Local Microstructure Control of Pure Aluminum Utilizing Fiber-Laser Aided Spot Heating System
Authors: Shibayanagi Toshiya , Tsukamoto Masahiro , Abe Nobuyuki , Matsumoto Takamasa , Soga Y.
Published: March 2009

Spot heating system utilizing a fiber-laser has been developed in order to control
recrystallization, grain growth process and texture development. The newly developed system
enables the laser beam to be focused onto the surface of specimen with a minimum diameter of
around 10 m. The maximum power of laser in the present system is 100W. Specimens of cold
rolled pure aluminum plates of 1mm thick are used for local recrystallization treatment by the spot
heating. After laser-spot heating, preferentially recrystallized grains appeared in the irradiated and
heat affected region with a diameter depending on the laser power density. The present system
enables spot heating on any critical points of the specimen surface. Some laser-heated specimen
show locally recrystallized regions occupied by almost single grain having similar crystallographic
orientation as that of cold rolled matrix. But the orientation of recrystallized grain is not always the
same as that of the matrix. Selective spot heating on grains having peculiar orientation would bring
about a possibility of texture control that has not been achieved by means of conventional materials
processing.
Effect of Niobium Addition on the Texture Formation of High Strength Cold-Rolled Low Carbon Steel Sheets
Authors: Yoshida Hiromi , Okuda Kaneharu , Kawabe Hidetaka , Urabe Toshiaki , Tanaka Yasushi , Hosoya Yoshihiro
Published: March 2009

The effect of niobium (Nb) addition on recrystallization texture formation in cold-rolled
low carbon steel sheets containing 2% manganese (Mn) was investigated. The microstructures of
hot-bands were significantly refined by Nb addition, which led to the development of the cold-rolling
texture in both the γ-fiber (<111>//ND-fiber) and the α-fiber (<110>//RD-fiber). Recrystallization
was retarded by Nb addition, in particular, the growth of <110>//ND grains was retarded. However,
the γ-fiber and {112}<110> grains developed during annealing even in the intercritical (α-γ) region.
Consequently, the r-value increased as the content of Nb was increased due to the development of the
intensity ratio of the <111>//ND texture to the <100>//ND texture, which is desirable for
deep-drawable high strength steel sheets.
Effect of Grain Boundary Migration on Texture Formation in Al-3mass%Mg Solid Solution during High Temperature Deformation
Authors: Okayasu Kazuto , Takekoshi Hiroki , Fukutomi Hiroshi
Published: March 2009

Uniaxial compression deformation is conducted on solid solution Al-3mass%Mg and
Al-3mass%Mg-0.2mass%Sc with Al3Sc precipitates in the strain rates ranging from 1.0×10-4s-1 to
5.0×10-3s-1 at 723K. High temperature yielding is observed. Fiber texture is constructed in all the
deformation conditions. While the main component of the fiber texture changes from {011} to
{001} in Al-3mass%Mg alloy with an increase in strain rate, no big change in texture main
component is seen for Al-3mass%Mg-0.2mass%Sc alloy with Al3Sc precipitates. It is
experimentally shown that the development of {001} fiber texture can be attributed to the grain
boundary migration.
Influence of Dynamic Recrystallisation on Texture Formation in ECAP deformed Nickel
Authors: Skrotzki Werner , Klöden Burghardt , Hünsche I. , Chulist Robert , Suwas Satyam , Tóth László S.
Published: March 2009

3N nickel has been deformed by equal channel angular pressing (ECAP) at 400°C up to 3 passes using route A. The texture with respect to position in the deformed billet, i.e. from top to bottom, has been measured with high-energy synchrotron radiation. It is characterized by texture components typical for simple shear in the intersection plane of the square-shaped 90° bent channel. Besides, an oblique cube component is observed. Orientation imaging microscopy clearly shows that this component is due to partial recrystallization. Intensities of the texture components as well as deviations from their ideal shear positions vary from the top to the bottom of the billet and with the number of passes. The change of the intensity of texture components and the texture gradient investigated is discussed. Special emphasis is put on the influence of dynamic recrystallization on texture and microstructure formation during ECAP of fcc metals.
Recrystallisation, Structure, Texture and Properties of Pipe Steel Rolled at Wide Temperature Range
Authors: Slavov V.I. , Popkova N.A. , Betsofen Sergei Ya.
Published: March 2009

Methods of complex X-ray and metallographic analyses have been used to investigate the influence of texture, thin structure and grain boundaries of coiled low-alloyed steel for gas-and-oil pipeline tubes after hot rolling on its mechanical properties. Finish rolling temperature changes in a wide range (ТFR = 8900С-5300С). Specifics of steel structure formation under conditions of dynamic (controlled rolling) and static (high-and-low temperature rolling) recrystallization have been found.
An Examination of Cluster Nucleation of Goss Oriented Grains Formed during Secondary Recrystallisation in an Fe-3.2% Si Electrical Steel
Authors: Duggan B.J. , Quadir M.Z. , Penelle Richard
Published: March 2009

The idea that a single subgrain is sufficient to produce a single recrystallised grain is the
simplest explanation for the recrystallisation process. Likewise, a single Goss oriented grain arising
from the primary recrystallisation process is the simplest unit which can give rise to a secondary
Goss oriented grain. More complicated cluster models, for example subgrain coalescence is also
considered feasible for primary recrystallisation, clusters of Goss oriented grains might be another
mechanism for forming Goss oriented secondary grains. This paper examines the cluster theory
using material which is produced by the ARMCO process which requires two stages of rolling. In
order to achieve this aim it is necessary to destroy the connectivity between individual Goss
oriented grains by using thin foils derived from sheet which gives a strong Goss texture on
conventional annealing. The foils were sectioned from the subsurface which had a strong η fibre
after primary recrystallisation, and ranged in thickness from 18μm (the average grain size after
primary recrystallisation) up to 80μm, which is the approximate thickness of the η textured layer.
The central layer, which had the classical {111} primary recrystallised texture, was similarly
processed, but this did not produce secondary recrystallisation. The experiment followed the
secondary recrystallisation process in the same area using sequential annealing in a vacuum furnace
by a combination of EBSD and Channelling contrast microscopy. The data does not support the
high energy boundary hypothesis nor the CSL explanation. But it is clear that connectivity is
important, because when this is destroyed by the thin foil two dimensional morphology, as it is in
the thinnest foil, secondary recrystallisation does not occur.
A Study of Abnormal Behavior of Grain Growth in High-Strength Boron-Added Steel
Authors: Lee You Hwan , Lee Sang Yoon , Lee Duk Lak
Published: March 2009

In order to save natural resources and to reduce production costs, many industries have
conducted studies on new developed steels and manufacturing processes. For instance, the use of
high-strength bolts can decrease the number, size and weight of bolts used in a car, thereby decreasing
fuel consumption. For this reason, steel makers are developing boron-added steel for high-strength
bolts, which eliminates production processes. However, it has been pointed out that this boron-added
steel is sensitive to austenite grain coarsening. The austenite grain coarsening does not occur
uniformly, hence it can affect mechanical properties such as tensile, fatigue and so on. Therefore, the
aim of this study is to investigate the abnormal behavior of grain growth and to determine the
optimum amount of alloying elements in boron-added steel for use in making high-strength bolts.
Dynamic Grain and Particle Growth in a Non-Superplastic Al-4Cu Alloy
Authors: Rofman Oleg V. , Bate Pete S.
Published: March 2009

The effect of deformation on the microstructure of a Al-4wt.%Cu alloy has been investigated. Evaluation of the microstructural changes was made by comparing results after both static annealing and tensile testing (deformed and non-deformed regions) at 450 °C. Uniaxial perturbed-rate tests showed that the Al-4wt.%Cu has a low value of the strain rate sensitivity index (m ~ 0.22) and cannot be considered as a superplastic material. It was found that in the deformed regions, specimens showed a significant increase in the grain and particle size. These changes were accompanied by an increase in the aspect ratio of the matrix grains. Tensile tests carried out at constant strain rates and stopped at intermediate strains helped to estimate the rate of the grain and particle growth and the contribution of deformation to it. To examine in detail the mechanism of the particle coarsening during deformation, additional tensile tests were made using the Al-4wt.%Cu alloy annealed at temperature conditions leading to abnormal grain size. Results of these tests also showed strain-induced particle coarsening, so that dynamic particle coarsening was not simply caused by boundary migration effects.
Biomimetic Coating on Zirconia Composites Induced by Chemical Treatment
Authors: Ortega-Chavarría S. , Cortés-Hernández Dora A. , Nogiwa-Valdez Akemi A.
Published: March 2009

The effect of the chemical treatment of zirconia/alumina composites followed by a biomimetic treatment has been studied. The composites are prepared from a powder mixture of Mg- PSZ and Al2O3. The powders are ball-milled in acetone and uniaxially pressed after drying. The specimens are sintered at 1550 °C in air. After sintering, chemical treatment is performed by immersing the samples in a 5M aqueous solution of phosphoric acid at 95 °C for 4 days. The biomimetic method consists of immersing the chemically-treated samples in simulated body fluid at 36.5 °C. In some cases a wollastonite bed is used as a supplier of calcium ions, resulting in the formation of a bonelike apatite layer. The presence of this bioactive system during the biomimetic process has a positive significant effect on the bioactivation of the composites for either short or long times of immersion of the composites in simulated body fluids. The chemical treatment increases also the rate of apatite formation at short immersion periods.
On the Fluid Flow and Mixing Phenomena in Ladles Equipped with Impeller and Gas Purging for Degassing of Al-Based Alloys
Authors: Ramírez-Argáez Marco , Contreras-Bustos F. , González-Rivera Carlos
Published: March 2009

In this work a fundamental Eulerian mathematical model is developed to simulate fluid
flow and mixing phenomena in aluminum ladles equipped with an impeller for dehydrogenization
treatment. The effect of rotating speed and type of impeller, depth of immersion, and gas flow rate,
on the mixing behavior and vortex formation is analyzed with this model. The model simulates
operation with and without gas injection and it is developed in the commercial PHOENICS 3.4
CFD code in order to solve all conservation equations governing the process, i.e., continuity, 3D
turbulent Navier-Stokes and k-ε turbulence model for a two-phase fluid flow problem using the
Inter Phase Slip Algorithm. In order to realistically represent the process, the shape of the furnace
and the impellers are modeled by employing Body Fitted Coordinates. It is concluded that the
mixing behavior is highly dependent on the rotation speed and impeller type. Mixing time is
improved when: the impeller is located at a depth of 0.229 m into the aluminum bath, and by using
high rotation speeds, ladles with a high ratio of diameter to height, and impellers with notches.
TEM Observations of Two-Phase Microstructure Formed by Phase Separation of Gamma-Prime Precipitates in Ni-Al-Si Alloys
Authors: Moritani Tomokazu , Ota Masahiro , Kozakai Takao , Doi Minoru
Published: March 2009

The phase-separation behaviour of γ’ precipitates in Ni-7.1Al-6.7Si alloy was
investigated by means of transmission electron microscopy (TEM). When the alloy is aged at
1173K, coherent spherical γ’ particles having ordered L12 structure appear in γ matrix having
disordered A1 structure. When the two-phase microstructure of γ + γ’ is aged at 973K, spherical γ
particles precipitate in the individual γ’ precipitates. In the course of ageing at 973K, the new γ
particles grow keeping the spherical shape, their number gradually decreases and finally γ particles
aging at 1173K gradually change their shape from sphere to cuboid, but do not practically change
their size, i.e. such phase-separation behaviour brings the decelerated growth of γ’ precipitates.
Explosive Welding of ZrTiCuNiBe Bulk Metallic Glass to Crystalline Metallic Plates
Authors: Chiba Akira , Kawamura Yoshihito , Nishida Minoru
Published: March 2009

Recently, a number of amorphous alloys that possess high glass-forming ability and a
wide supercooled liquid region before crystallization have been discovered. Especially, bulk
metallic glasses, which are made in bulk form with a thickness of ~10 mm at slow cooling rates of
the order of 1~100 K/s, have been noted as an industrial application. Hence the welding of bulk
metallic glasses to other materials is very important. Explosive welding of most popular
Zr41.2Ti13.8Cu10Ni12.5Be22.5 bulk metallic glass to crystalline pure Ti and SUS304 plates is
investigated in this paper. The BMGs was found to retain the amorphous structure and the original
mechanical properties. The sound bonding with other materials is expected to push forward the
application of bulk metallic glass for industrial usage.
Explosion Joining of Magnesium Alloy AZ31 and Aluminum
Authors: Ghaderi Seyed Hadi , Mori Akihisa , Hokamoto Kazuyuki
Published: March 2009

Explosion welding has produced a large number of dissimilar joints. But the explosion welding of materials of low impact toughness and brittle nature is considered to be difficult. Magnesium, with its HCP structure, has a low capacity for plastic deformation at room temperature and moreover it has a high chemical reactivity. Therefore, successful explosion welding of magnesium alloys, demands careful attention to be paid to prevent failure or formation of brittle reacted zones at the weld interface. Explosive welding of the wrought Mg-Al-Zn alloy and commercially pure aluminum is performed. The welds are analyzed through metallographic characterization and shear tests. High quality welds of the two materials possessing shear strength higher than the softer layer has been obtained.
Numerical Studies of Explosive Welding by SPH
Authors: Tanaka Katsumi
Published: March 2009

A particular characteristic of an explosively produced weld is that the profile of the weld
interface often has a regular wavy appearance. An effect of detached shock wave and jetting on the
metal interface of explosive welding has been shown by SPH (Smoothed particle hydrodynamics).
Numerical results show wavy interface which is observed in several experiments. High speed jet
between interface and Karman vortex after oblique impact of a flyer plate to a parent plate were major
mechanism of explosive welding.
Comparative Studies on Microstructure and Mechanical Properties of CrN, Cr-Mo-N and Cr-Si-N Coatings
Authors: Yun Ji Hwan , Ahn Sung Kyu , Kim Kwang Ho
Published: March 2009

CrN-based multi-component coatings were deposited by a hybrid coating system
combining the arc ion plating (AIP) and sputtering technique. In this work, comparative studies on
microstructure and mechanical properties of microhardness and wear behavior among CrN, Cr-Mo-
N, Cr-Si-N coatings were systematically conducted. Adding Mo and Si atoms into CrN coatings had
important effects on microstructural change and mechanical properties of CrN coatings. The
maximum hardness values of Cr-Mo-N and Cr-Si-N coatings were the same value of 34GPa, These
values were much enhanced compared with 18GPa of CrN coating. The average friction coefficient
of CrN-based coatings decreased to 0.37 and 0.2 with the incorporation of Mo and Si content
Two-Step Planarization of ECMP and CMP for MEMS Copper Patterns
Authors: Jeong Suk Hoon , Joo Suk Bae , Lee Ho Jun , Park Boum Young , Kim Hyoung Jae , Jeong Hae Do
Published: March 2009

Chemical mechanical polishing (CMP) has been used as planarization process in the
fabrication of semiconductor devices. The CMP process is required to planarize the overburden film
in an interconnect process by high relative velocity between head and platen, high pressure of head
and chemical effects of an aqueous slurry. But, a variety of defects such as dishing, delamination and
metal layer peering are caused by CMP factors such as high pressure, pad bending and strong
chemical effect. The electrical energy of the electro-chemical mechanical planarization (ECMP)
dissolves copper (Cu) solid into copper ions electrochemically in an aqueous electrolyte. The
dissolved copper complex layer or passivation layer is removed by the mechanical abrasions of
polishing pad and abrasive. Therefore the ECMP process realizes low pressure processing of soft
metals to reduce defects comparing to traditional CMP process. But, if projected metal patterns were
removed and not remained on whole wafer surface in final processing stage, Cu layer could not be
removed by ECMP process.
The two-step process consists of the ECMP and the conventional CMP used in micro patterned Cu
wafers. First, the ECMP process removed several tens 'm of bulk copper on Cu patterned wafer
within shorter process time than the Cu CMP. Next, residual Cu layer was completely removed by the
Cu CMP under low pressure. Total time and process defects are extremely reduced by the two-step
process.
The Effects of Various Substrate Temperature of Bi2O3 Buffer Layer on SBT (SrBi2Ta2O9) Thin Films Deposited by R.F. Magnetron Sputtering
Authors: Yoon Ji Eon , Cha Won Hyo , Hwang Dong Hyun , Lee Chul Su , Lee In Seok , Son Young Gook
Published: March 2009

The SBT(SrBi2Ta2O9) thin films with Bi2O3 buffer layer were deposited on Pt/Ti/SiO2/Si
substrate by R.F. magnetron sputtering method in order to improve the ferroelectric characteristics. In
SBT thin films, the deficiency of bismuth due to its volatility during the process results in an obvious
non stoichiometry of the films and the presence of secondary phases. Bi2O3 buffer layer was found to
be effective to achieve lower temperature crystallization and improve ferroelectric properties of SBT
thin films. Ferroelectric properties and crystallinities of SBT thin films with various substrate
temperature of Bi2O3 buffer layer were observed, using X-Ray Diffraction (XRD), Precision LC
(Radient Technologies. Inc.) and GDS (glow discharge spectrometer).
Removal of Carbon Nanoparticle Using NO2 Oxidation Technique
Authors: Jung Jae Hee , Choo Jung Bum , Kim Sang Soo
Published: March 2009

In diesel engine, generally, the removal of carbon nanoparticles has been based on a
filtration system or oxidation reactor with O2 at high temperatures of above 800 °C. Recently, NO2
has been found to be a more efficient oxidant than O2 at lower temperatures in the range of 200~500
°C. Small amounts of NO2 in the range of a few hundreds of ppm by volume can promote the
continuous oxidation of carbon particulates. Thus far, experiments involving diesel PM (particulate
matter) oxidation by NO2 are only practiced as regards the soot deposited on filters or plates.
However, in aerosol state, depending on the surrounding temperature and the NO2 concentration,
the carbon nanoparticle removal rate is significantly different. Therefore, the study of nano-sized
carbon aerosol oxidation in various gas circumstances is required. In this study, the oxidation
characteristics of nano-sized carbon aerosol particles in NO2 condition are investigated.
Effect of SPS on Surface Characteristics of Gas-Atomized Mg-6wt%Al-1wt%Zn Alloy by Non-Hazardous PEO Treatment
Authors: Chang S.Y. , Lee Du Hyung , Cho H.G. , Song Yo Seung , Kim Sung Ho , Lee Chan Bock
Published: March 2009

The Mg-6wt%Al-1wt%Zn alloy powders mixture produced by gas atomization were spark
plasma sintered (SPSed). The SPSed sample was coated by plasma electrolytic oxidation (PEO)
method, and the microstructure, mechanical and corrosion properties were investigated and compared
to the normally sintered sample. The SPSed sample exhibited a microstructure of well-bonded grains
with approximately 48 ,m in grain size, which was bigger than that of the normally sintered sample.
The coatings on the SPSed sample were characterized by dense and porous layers, while, in the case
of the normally sintered sample, the coatings had grown through the grain boundary of substrate with
increasing the coating time. The surface roughness, thickness and micro-hardness of coatings on the
SPSed sample increased gradually with increasing the coating time. The corrosion property of
coatings on the SPSed sample had a tendency to improve with increasing the coating time in
3.5%NaCl solution. However, it was worse than that of coatings on the normally sintered sample.
Mineralogical Characterization of Villa Reyes México Kaolin for Industrial Applications
Authors: Vázquez Acosta F. , Torres-Martínez Leticia M. , Garza-Tovar Lorena L. , Martínez-de la Cruz A. , López González Wallter
Published: March 2009

A kaolin obtained from a region near to San Luis Potosí (México) was characterized
by X-ray powder diffraction (DRX), optical microscopy (OM), scanning electron microscopy
(SEM), X-ray fluorescence (XRF), thermal analysis (DTA/TGA), and chemical analysis.
Mineralogical and morphological characteristics of the mineral are presented. The kaolin sample
was formed mainly by kaolinite, but other minor phases were also detected such as quartz,
cristobalite, trydimite, and dolomite. For iron lixiviation process, concentrate HCl was
employed. The high content of volcanic glass detected, evidenced by optical microscopy,
revealed an incomplete kaolinization process of the raw material. In agreement with these
results, X-ray fluorescence analysis showed high- SiO2 and low-Al2O3 content in the sample as is
expected on weakly kaolinized materials.
Phase Analysis in the Region Brazed with Ni-14Cr-10Co-3.5Al-2.5Ta-2.8B Filler Metal Using Electron Backscatter Diffraction
Authors: Kim Yong Hwan , Kwun S.I.
Published: March 2009

The phases formed in the wide-gap region brazed with Ni-14Cr-10Co-3.5Al-2.5Ta-2.8B
filler metal powder in IN738 superalloy were investigated by electron backscatter diffraction (EBSD).
The wide-gap brazing process was carried out in a vacuum of 2×10-5 torr at 1503 K. The region brazed
with filler metal powders had a microstructure consisting of two kinds of eutectic colonies, one is Ni
solid solution-CrB eutectic and the other is Ni solid solution-Ni3B eutectic. EBSD pattern analysis
revealed that the CrB phase had orthorhombic structure with lattice parameters of a=0.297, b=0.786
and c=0.293 nm, and the Ni3B phase had orthorhombic structure with lattice parameters of a=0.439,
b=0.522 and c=0.662 nm. The cuboidal-shaped phase precipitated in the Ni solid solution was found
to be the γ' (Ni3Al) phase, which had cubic structure with lattice parameter of a=0.357 nm.
Electrolytic Manganese Dioxide Nucleation and Growth on Titanium Substrates
Authors: Dutra A.J.B. , Almeida I.C.F.
Published: March 2009

Electrolytic manganese dioxide (EMD) nucleation and growth on titanium substrates
from acidic manganese sulfate solutions was studied at 65oC and 90oC at different potentials and
sulfuric acid concentrations. Electrochemical experiments allied to SEM examination were
performed to characterize the mechanism of nucleation and its evolution with time. The EMD
powder produced after a constant charge electrolysis of 448 mA·h was analyzed by SEM, BET,
DTA/TG and X-ray diffraction. Results indicated that depending on the experimental conditions
nucleation can be either progressive or instantaneous and when three-dimensional nuclei were
formed the manganese dioxide deposit presented a higher specific surface area. Surface areas
ranging from 51.8 to 168.8 m2/g were obtained under the conditions tested.
Processing and Simulation for Consolidation of Nanostructured Al-Cu Powder Alloys
Authors: Peres M.M. , Fogagnolo J.B. , Jorge Alberto Moreira , Kiminami Claudio Shyinti , Botta Filho Walter José , Bolfarini Claudemiro
Published: March 2009

Nanostructured aluminium-based alloys are light yet much stronger than conventional materials, which offer technological opportunities for applications such as in aerospace industry. One of the alloys of great interest for such applications is based on Al-Cu system and one of the main challenges for development of such alloys are associated with powder processing. However, processing such powder alloys into bulk material requires relatively low temperature and high pressure, which presents significant processing difficulties. A two-step approach is being explored in our group to reach the goal of a fully dense bulk material. Firstly, cold pressing is used to partially consolidate the powder material and secondly, hot extrusion is used to consolidate the alloy to full density. Process modelling is being used to design the extrusion process, including the extrusion ratio and extrusion length, to limit the temperature increase during extrusion as a result of adiabatic heating, and to avoid excessive heating to limit the undesirable grain growth of the material. A parametric study of extrusion parameters is presented and processing parameters are recommended. The use of process modelling has proven to be a useful tool in understanding the results from the extrusion experiments and limiting the number of interactions during extrusion.
Laser Annealing of Implanted Semiconductor Layers – One Bridge to Nano-Processing
Authors: Geiler Hans D.
Published: March 2009

About 25years after inventing the laser annealing effects of ion implanted semiconductors
a summary of the related physical phenomena is given. The field of application for short and
selectively deposited energy pulses in controlled thermally activated processing is critically
reviewed with the emphasis on electrical activation of implanted layers. Starting form the energy
deposition and continuing to the excited transport phenomena a set of regimes can be described,
which allows the classification of the variety of laser annealing methods and their different
application. Within the scope of controlled thermally activated processes in nanometer dimensions
old phenomena like phase transitions in strong non-equilibrium to create metastable states or
producing dissipative structures by nonlinear coupling effects with self-organization are taken into
account for device generations beyond 45nm. The challenges and disadvantages of laser annealing
methods for planar semiconductor technology will be elaborated with respect to the current progress
in laser development.
Vacancy Engineering – An Ultra-Low Thermal Budget Method for High-Concentration 'Diffusionless' Implantation Doping
Authors: Cowern Nicholas E.B. , Smith Andrew J. , Bennett Nicholas S. , Sealy Brian J. , Gwilliam Russell , Webb Roger P. , Colombeau Benjamin , Paul Silke , Lerch Wilfried , Pakfar Ardechir
Published: March 2009

This paper reviews the physics and the potential application of ion-implanted vacancies
for high-performance B-doped ultra-shallow junctions. By treatment of silicon films with vacancygenerating
implants prior to boron implantation, electrically active boron concentrations
approaching 1021 cm-3 can be achieved by Rapid Thermal Annealing at low temperatures, without
the use of preamorphisation. Source/drain (S/D) junctions formed by advanced vacancy engineering
implants (VEI) are activated far above solubility. Furthermore, in the case of appropriately
engineered thin silicon films, this activation is stable with respect to deactivation and the doping
profile is practically diffusionless. Sheet resistance Rs is predicted to stay almost constant with
decreasing junction depth Xj, thus potentially outperforming other S/D engineering approaches at
the ‘32 nm node’ and beyond.
Advanced Millisecond Annealing Technologies and its Applications and Concerns on Advanced Logic LSI Fabrication Processes
Authors: Kase Masataka , Yamamoto Tomonari , Kubo Tomohiro
Published: March 2009

The recent progress of advanced millisecond annealing (MSA) technology is discussed for
the application to the advanced logic LSI fabrication processes. The combination with conventional
spike annealing and MSA is proving practical to reduce the parasitic resistance and control the dopant
diffusion. The characterization result of advanced 45 nm generation devices including the channel
straining technology using embedded SiGe epitaxial growth is described with the arrangements of
process flow and annealing steps. MSA has a principle problem of the annealing temperature
variation depending on the optical properties of materials on the wafer surface because the annealing
process time is similar to the heat transfer time. In the device scale, the variation of temperature is
examined as the exact temperature with newly proposed evaluating methods used for the first time in
this industry.
Advanced Annealing Schemes for High-Performance SOI Logic Technologies
Authors: Feudel Thomas
Published: March 2009

We have extensively studied the impact of advanced annealing schemes for highperformance
SOI logic technologies. Starting with the 130 nm technology node, we introduced
spike rapid thermal annealing (sRTA). Continuous temperature reduction combined with implant
scaling helped to improve transistor performance and short channel behavior. During the
development of the 90 nm technology we evaluated flash lamp and laser annealing (FLA). These
techniques became an essential part of the 65 nm node. At this node we also faced major challenges
in terms of compatibility with new materials like SiGe as well as the need for reduction of process
parameter fluctuations. Scaling will be continued with the 45 nm technology node towards a truly
diffusionless process.
The Corrosion Behaviors of Heat-Treated SAE 8620 Steels
Authors: Hong Steven , Lin H.C. , Lee Y. , Lian T.S. , Tseng L.Y. , Lin K.M.
Published: March 2009

The corrosion behaviors, including the immersion corrosion, electro-chemical corrosion,
stress-corrosion fracture, of heat-treated SAE 8620 steels have been investigated. Experimental
results show that the 400°C􀊳 tempered specimen is only susceptible to local attack of pitting
corrosion and can exhibit an excellent corrosion resistance during the static immersion and
electro-chemical tests in a 3.5% NaCl solution. The tensile strength and elongation of the
normalized and 300~500°C tempered specimens will be reduced when tested in NaCl solutions,
especially at a higher testing temperature. The normalized specimen can inhibit effectively the
crack-growth under constant loading and the 300~500°C tempered specimens have a sequence of
crack-growth rate as 300°C > 400°C > 500°C.