bluuebunny/crossref_metadata_2025 huggingface dataset:
Void Formation in Magnetite Scale Formed on Iron at 823 K -Elucidation by Chemical Potential Distribution-
Authors: Ueda Mitsutoshi , Kawamura Kenichi , Maruyama Toshio
Published: March 2009

Estimation of void formation in oxide scale is important for predicting exfoliation of the
oxide scale. Void formation in magnetite scale formed on iron at 823 K has been elucidated by
chemical potential distribution, flux of oxide ion and its divergence. This calculation also estimates a
effective diffusion coefficient, which includes both lattice diffusion and grain boundary diffusion in
magnetite scale. The resulting effective diffusion coefficients give the quantitative elucidation of the
morphology of the magnetite scale. The divergence of oxide ion explains well a position and an
amount of void in magnetite scale.
Formation of Ni Aluminide Layer Containing La by Molten-Salt Electrodeposition and Cyclic-Oxidation Resistance
Authors: Fukumoto Michihisa , Hara Motoi , Narita Toshio
Published: March 2009

In order to improve the cyclic-oxidation resistance of Ni and SUS304 steel, the coating of
a Ni aluminide containing La on both samples were carried out by the electrodeposition of Al and
La in a molten salt. The electrodepositions of Al and La were conducted using a potentiostatic
polarization method at 1023 K in an equimolar NaCl-KCl melt containing 3.5 mol%AlF3, and that
containing 4 mol%La2O3-24 mol%NH4Cl, or 3.5 mol%LaF3. Observation and analysis of the
cross-section of the specimen after polarization showed that a deposited layer consisting of a thick
inner Ni aluminide layer and a thin outer layer containing a large amount of La was formed on both
samples. The cyclic-oxidation resistance of the Ni specimen covered with the deposit layer having
the La layer as the outer layer was higher than those of the untreated Ni specimen and the Ni
specimen coated with the deposit layer without La. The stainless steel covered with the Ni
aluminide showed a high cyclic-oxidation resistance in the atmosphere containing water vapor at
1273 K in comparison with untreated stainless steel, without depending on the existence of La in
the deposited layer.
Interaction between Mechanical Loading in Creep and Reactivity of Zirconium and Zircaloy in Temperature
Authors: Moulin Gérard , Tahhan Rania El , Favergeon Jérôme , Viennot Michel , Berger Pascal
Published: March 2009

In order to study the nucleation and growth of cracks in the outer oxide scale which
expand into the underlying alloy, deformation in creep in oxygen or in vacuum of zirconium and
Zircaloy-4 has been studied mainly at 500°C. Influence of applied stresses, atmosphere and alloy’s
grade on the deformation and oxidation processes are especially analyzed. The results underline the
presence of two distinct deformation domains for both alloys grades, depending on the applied
stress value. The presence of the oxide scale leads only to slight modifications on the deformation
mechanism but it induces an increase of the deformation rate. This enhancement is especially
observed in the case of the pre-oxidized Zircaloy-4 whose cracks remain mainly located in the outer
part of the oxide. In opposite, the pre-oxidized zirconium shows cracks located down to the
underlying metal. Acoustic emission is used to follow, in situ, in temperature the damage process of
the outer zirconia layer during creep, and precisions about the oxidation mechanism and the effect
of applied stress on oxygen diffusion and oxide growth rate are obtained thanks to the use of 18O as
a marker.
Quantitative Adhesion Energy Values of Chromia-Rich Thermal Oxides on Stainless Steels Determined by Blister and Tensile Tests
Authors: Galerie Alain , Dupeux M. , Wouters Yves , Toscan F.
Published: March 2009

Adhesion energy values for thermal oxide scales cyclically grown at 850 and 950°C in
air on ferritic and austenitic stainless steels were obtained using an inverted blister test and a tensile
test working in the SEM chamber. The blister test used water pressure for debonding the metalscale
interface, whereas the tensile test led to transverse compression generating scale spallation by
buckling. Adhesion energy, defined by energy for interface crack propagation by unit area, was
shown to be in the range 10 to 650 J.m–2 for the chromia-rich scales with thickness in the
micrometer range. Ferritic grades gave less adherent scales than austenitic ones, and a great
influence of titanium was evidenced, greatly increasing scale adhesion; niobium was less operative.
Adhesion was well connected with nature and morphology of Ti and/or Nb-containing precipitates
at the metal-scale interface.
Influence of Cooling Rate and Steel Composition on the Scale Failure Characteristics during Cooling of Si-Containing Low Carbon Steels
Authors: Taniguchi Shigeji , Hanamoto Yuki , Nakata Junji
Published: March 2009

The scale failure temperature (Tf) during cooling from 1173 K of low carbon steels
containing Si of up to 2.1% was assessed by in-situ acoustic emission measurements and analyses
including wavelet transform. In general, Tf lowers with an increase in the Si content for steels
without S or P, indicating that the scales on higher Si-content steels are more resistant to thermal
stress. This tendency becomes larger for higher cooling rate. Contrarily, Tf rises with an increase in
the S, P or (S+P) content for 1% Si steels. This means that the scale failure is enhanced by the
additives. S segregates at the scale/substrate interface and seems to enhance the partial scale
separation. P is incorporated in the (FeO+SiO2) layer on the substrate and forms microspores at the
interface to the FeO layer, and thus enhanced the crack initiation by providing the sites for stress
concentration. Wavelet transform showed that the scale failure mode is mainly the following; local
separation of the scale over a small area takes place first, and then cracking in the scale follows. For
steels containing S or/and P scale cracking is the initial failure in many cases, probably because the
stress concentration sites are already formed during the scale growth.
The Role of Copper in Resisting Metal Dusting of Ni-Base Alloys
Authors: Nishiyama Yoshitaka , Otsuka Nobuo
Published: March 2009

The present study focuses on a new technique for the prevention of metal dusting in carbonaceous gas environments at intermediate temperature. Preliminary laboratory metal dusting test was conducted for Ni-x%Cu binary alloys and Ni-Cr alloys with various Si and Cu content in a simulated 60%CO-26%H2 -11.5%CO2-2.5%H2O (in vol.%) gas mixture at 650°C. Specimens of the binary alloys containing low Cu were entirely covered with coke and showed rough metal surfaces due to the degradation of metal. Alloys of 20% and more Cu, on the contrary, had no coke deposition and smooth metal surfaces, suggesting alloys with an adequate Cu do not react with CO in the syngas mixture without an oxide scale barrier. Based on these results, we conclude that Cu does not protect by formation of the oxide scale but has a “Surfactant-Mediated Suppression” against metal dusting. This effect can be explained in terms of atomistic interaction of CO with transition-metal surfaces by electronic structure analyses. For the Ni-Cr alloy, both addition of Si and Cu played a role of preventing pit formation in the simulated syngas atmosphere. The concept can be also useful for the practical material design of Ni-Cr-Si-Cu alloy with excellent metal dusting resistance.
Modern Analytical Techniques in High Temperature Oxidation and Corrosion
Authors: Graham Mike J.
Published: March 2009

Modern analytical techniques are useful to characterize oxide films and to study oxide
growth processes. This paper will summarize some of our work on the high temperature oxidation
of both metals and semiconductors. Systems considered include binary III-V semiconductors, e.g.
GaAs, which unlike silicon does not normally form high-quality native oxide. For GaAs, the
influence of deuterium in the substrate and surface platinum have been evaluated with respect to
oxide growth. Both aluminum-containing alloys (FeCrAl and NiAl) and semiconductors (AlGaAs,
InAlAs and InAlP) are included. The objective is to produce good quality protective and insulating
aluminum-containing oxides. In these studies, the application of several modern surface- analytical
techniques, particularly Auger electron spectroscopy, X-ray photoelectron spectroscopy and
secondary ion mass spectrometry, complemented by other techniques, e.g. transmission electron
microscopy and X-ray analysis provides useful information on the chemical composition of the
oxides and leads to a better understanding of oxidation and corrosion phenomena. In the case of
AlGaAs and InAlP, thermal oxidation produces aluminum-containing oxides that have good
insulating characteristics which makes the oxide films potentially useful for some device
applications.
Inter- and Intragranular Stress Determination with Kossel Microdiffraction in a Scanning Electron Microscope
Authors: Pesci Raphaël , Inal Karim , Berveiller Sophie , Patoor Etienne , Lecomte Jean Sébastien , Eberhardt André
Published: March 2009

A Kossel microdiffraction experimental set up is under development inside a Scanning
Electron Microscope (SEM) in order to determine the crystallographic orientation as well as the
inter- and intragranular strains and stresses on the micron scale, using a one cubic micrometer spot.
The experimental Kossel line patterns are obtained by way of a CCD camera and are then fully
indexed using a home-made simulation program. The so-determined orientation is compared with
Electron Back-Scattered Diffraction (EBSD) results, and in-situ tests are performed inside the SEM
using a tensile/compressive machine. The aim is to verify a 50MPa stress sensitivity for this
technique and to take advantage from this microscope environment to associate microstructure
observations (slip lines, particle decohesion, crack initiation) with determined stress analyses.
Strengthening of Si3N4 Ceramics by Laser Peening
Authors: Akita Koichi , Sano Yuji , Takahashi Kazuma , Tanaka Hirotomo , Ohya Shin Ichi
Published: March 2009

Laser peening has been applied to silicon nitride (Si3N4) ceramics without any pre-coating.
X-ray diffraction study revealed that plastic strain was introduced into the surface layer of the
ceramics. Compressive residual stress was also imparted, which became larger with increasing peak
power density of irradiated laser pulses. Surface roughness significantly increased due to ablative
interaction of the surface with laser pulses. A Weibull plot of four-point bending test results clearly
showed the increase of the bending strength and Weibull modulus by laser peening in spite of the
increase of the surface roughness.
Manufacture of Electrodes for Electro-Discharge Machining (EDM) of Complex Surfaces in Moulds
Authors: Pereira Navaza P. , Ares E. , Diéguez Jose L. , Pereira A.
Published: March 2009

In the present consumer, the personalization and originality of the made polymeric
products it is one of the area in which dwells efforts of investigation take it pleases. Many
companies uses plastic recipients that dog be painted or wrapped with to plastic but to however, the
development of artistic relief plows not developed. The biggest problem was obtaining an artistic
process out. In manual a way, it is very complicated, and there was not specific software to develop
this kind of work because they were designed to carry out tech-line pieces. The aim of this work is
to develop to method to produces to 3-D relief, an artistic appears and some letters, in a mould.
On Separating Oxide Charges and Interface Charges in 4H-SiC Metal-Oxide-Semiconductor Devices
Authors: Habersat Daniel B. , Lelis Aivars J. , Lopez G. , McGarrity J.M. , McLean F. Barry
Published: March 2009

We have investigated the distribution of oxide traps and interface traps in 4H Silicon
Carbide MOS devices. The density of interface traps, Dit, was characterized using standard C-V
techniques on capacitors and charge pumping on MOSFETs. The number of oxide traps, NOT, was
then calculated by measuring the flatband voltage VFB in p-type MOS capacitors. The amount that
the measured flatband voltage shifts from ideal, minus the contributions due to the number of filled
interface traps Nit, gives an estimate for the number of oxide charges present. We found Dit to be in
the low 1011cm−2eV−1 range in midgap and approaching 1012 −1013cm−2eV−1 near the band
edges. This corresponds to an Nit of roughly 2.5 ⋅1011cm−2 for a typical capacitor in flatband at
room temperature. This data combined with measurements of VFB indicates the presence of roughly
1.3 ⋅1012cm−2 positive NOT charges in the oxide near the interface for our samples.
Ellipsometric and XPS Studies of 4H-SiC/SiO2 Interfaces, and Sacrificial Oxide Stripped 4H-SiC Surfaces
Authors: Guy Owen James , Chen L. , Pope G. , Teng K.S. , Maffeis T. , Wilks S.P. , Mawby Philip  Andrew , Jenkins T.E. , Brieva A. , Hayton D.J.
Published: March 2009

The investigation of the silicon carbide surface after a sacrificial silicon oxidation
technique is reported. Oxidation of SiC is a necessary step in the fabrication of MOS devices and
device termination features such as field plates. Device processing requires the etching of windows
through the oxide layer to form features such as metal / SiC contacts. However, this work indicates
that a thin interfacial Si-O-C layer is still present after etching the oxide with hydrofluric acid (HF).
Ellipsometry and X-ray photoelectron spectroscopy (XPS) have been used to evaluate this
interfacial layer formed after oxide growth and after subsequent removal of oxide layers.
An XPS analysis of the surface after removal of the oxide revealed that silicon, oxygen and
carbon were all present in the remaining layer, which could not be removed by annealing at
temperatures up to 1000°C. The Si-O-C layer could be eliminated by altering the oxidation
conditions or by using a sacrificial silicon layer oxidation process.
Ni Schottky barrier diodes fabricated on the 4H-SiC surface after removal of the oxide, displayed
slightly higher ideality factors than those of diodes fabricated on untreated 4H-SiC samples.
Process Optimisation for <11-20> 4H-SiC MOSFET Applications
Authors: Blanc Caroline , Tournier Dominique , Godignon Philippe , Brink D.J. , Soulière Véronique , Camassel Jean
Published: March 2009

We report on 4H-SiC MOSFET devices implemented on p-type <11-20>-oriented epitaxial layers, using a two-step procedure for gate oxide formation. First is a thin, dry, thermal SiO2 layer grown at 1050°C for 1 hour. Next, is a thick (50 nm) layer of complementary oxide deposited by PECVD using TEOS as gas precursor. With respect to the standard thermal oxidation process, this results in much improvement of the field effect mobility. For the best samples, we find a peak value in the range of 330 cm2/Vs while, on the full wafer, an average mobility of about 160 cm2/Vs is found. Up to now, this is one of the best results ever reported for 4H-SiC MOSFETs.
Determination of the Temperature and Field Dependence of the Interface Conductivity Mobility in 4H-SiC/SiO2
Authors: Pennington Gary , Potbhare Siddharth , Goldsman Neil , Habersat Daniel B. , Lelis Aivars J.
Published: March 2009

In this work we present a comparison between the field-effect (FE) and conductivity
(inv) mobilities calculated from ID-VG measurements on a 4H-SiC MOSFET. A compact device
model is used to determine inv. The conductivity mobility is found to be larger than FE near room
temperature, but less than FE at 500K. These results are due to a reduction in charge trapping at
higher temperatures. In strong inversion, inv decreases markedly with increasing temperature.
Modeling indicates that surface phonon scattering dominates in this regime.
High Temperature Annealing Study of Al2O3 Deposited by ALCVD on n-Type 4H-SiC
Authors: Avice Marc , Grossner Ulrike , Nilsen Ola , Christensen Jens S. , Fjellvåg Helmer , Svensson Bengt Gunnar
Published: March 2009

Al2O3 has been grown by Atomic Layer Chemical Vapour Deposition (ALCVD) on ntype
4H-SiC using O3 as an oxidant. After post-deposition, annealing at high temperature (1000°C)
in Argon atmosphere for different time periods (1h, 2h, 3h) was performed. Bulk and interface
properties of the as-grown as well as the annealed films were studied by electrical measurements
(CV, IV, DLTS) and Secondary Ion Mass Spectrometry (SIMS) measurements. The electrical
measurements show a decreasing shift of the flatband voltage indicating a diminution of the
negative oxide charges with increasing annealing time. After annealing at 1000°C for 3h, the
flatband voltage shift has decreased to 6V. The SIMS measurements indicate a double interface with
a SiOx (x ≤ 2) interlayer in the as-grown samples while only one interface is observed after
annealing, leading to improved electrical behavior of the Metal-Oxide-Semiconductor devices.
Structural and Morphological Properties of Ultrathin HfO2 Dielectrics on 4H-SiC (0001)
Authors: Tanner Carey M. , Lu Jun , Blom Hans Olof , Chang Jane P.
Published: March 2009

The material properties of HfO2 thin films were studied to evaluate their potential as a
high-κ gate dielectric in 4H-SiC power metal-oxide-semiconductor field effect transistors.
Stoichiometric HfO2 films were deposited on n-type 4H-SiC (0001) by atomic layer deposition
(ALD) at substrate temperatures of 250-450°C. No significant interfacial layer formation was
observed by in-situ X-ray photoelectron spectroscopy (XPS) and an abrupt interface was confirmed
by high-resolution transmission electron microscopy (HRTEM). A temperature-dependent
transition from amorphous layer-by-layer growth to crystalline three-dimensional island growth
was identified by in-situ reflection high-energy electron diffraction (RHEED) and ex-situ atomic
force microscopy (AFM). X-ray diffraction (XRD) confirmed the presence of monoclinic HfO2
domains in crystallized films.
Theoretical Study of an Effective Field Plate Termination for SiC Devices Based on High-k Dielectrics
Authors: Brezeanu M. , Badila M. , Brezeanu Gheorghe , Udrea F. , Boianceanu C. , Amaratunga G. , Zekentes Konstantinos
Published: March 2009

A classical implementation of the field plate technique is the oxide ramp termination.
This paper presents improvements of the breakdown voltage for both SiC JBDs and SBDs, obtained
by using high-k dielectrics. A study regarding the influence of the dielectric permittivity and
thickness on the off-state performances of the diodes is included. It is shown that Si3N4 is to be
preferred to SiO2 for the dielectric ramp. Termination efficiencies up to 96% are reported.
Augmented CMP Techniques for Silicon Carbide
Authors: Kuo Peter , Currier Ian
Published: March 2009

Chemical-mechanical polishing (CMP) has proven a powerful tool for the final polishing
of semiconductor and compound semiconductor substrates such as silicon, sapphire, gallium
arsenide, and indium phosphide. For these materials, conventional CMP techniques have been able
to produce removal rates of several μm/hr while achieving pristine, epi-ready surfaces with
subsurface damage less than 10[nm]. For certain materials of interest in the compound
semiconductor community, particularly silicon carbide (SiC) and the III-V nitrides, conventional
CMP techniques perform poorly. These materials are extremely chemically inert, negating the
desired chemical effect leading to removal rates of less than 0.1[μm/hr]. These materials are also
very brittle and take damage easily, so a significant amount of material must be removed to ensure a
sufficiently low subsurface damage for epitaxy.
This paper documents the improvements made in the CMP of 4H and 6H SiC by augmenting a
colloidal silica slurry with chemical additives and with special treated nano size diamond particles.
The chemical additives proved most effective on 4H SiC, enhancing the slurry’s chemical effect and
improving its removal rate. For both materials, the addition of the diamond (Chemical-Mechanical
Polish with Diamond, CMP-D) greatly enhanced the removal rate and provided strong synergy
between mechanical strain and chemical effect resulting in low subsurface damage.
Mechanical Testing of Flexible Silicon Carbide Interconnect Ribbons
Authors: Panday R. , Fu Xiao An , Rajgopal Srihari , Lisby T. , Nikles S.A. , Najafi K. , Mehregany Mehran
Published: March 2009

This paper explores polycrystalline 3C-silicon carbide (poly-SiC) deposited by LPCVD
for fabricating flexible ribbon cable interconnects for micromachined neural probes. While doped
silicon is used currently, we hypothesized that poly-SiC will provide enhanced mechanical
robustness due to SiC’s superior mechanical properties. Paralleling prior work in silicon, forty-two
different designs were fabricated from nitrogen-doped poly-SiC films deposited by LPCVD at
900°C using dichlorosilane and acetylene as precursors. The different designs were then tested in
bending and twisting modes. Curved beams were found to bend nearly 250% more than straight
beams before fracture. Longer beams withstood greater bending and twisting due to greater
compliance. Longer and narrower beams generally outperformed shorter beams irrespective of
design. Also, doped poly-SiC beams had, on average, breaking angles that were greater than those
of identical doped silicon beams by ~50% in bending and ~20% in twisting modes. The paper
details the designs studied, describes the fabrication process for the test structures and
compares/contrasts the testing and simulation results related to the different designs to identify best
design practices.
Micromachining of Novel SiC on Si Structures for Device and Sensor Applications
Authors: Förster Christian , Cimalla Volker , Stubenrauch M. , Rockstuhl Carsten , Brueckner Klemens , Hein Matthias A. , Pezoldt Joerg , Ambacher Oliver
Published: March 2009

In this paper the multifariousness of SiC/Si heterostructures for device and sensor applications
will be demonstrated. 3C-SiC based microelectromechanical resonator beams (MEMS) with
different geometries actuated by the magnetomotive effect operating under ambient conditions were
fabricated. The resonant frequency reaches values up to 2 MHz. The applications of these resonators
are the measurement of the viscosity of liquids or mass detection. Furthermore, photonic devices in
the form of SiC/Si infrared gratings for wavelength and polarization filters in infrared spectra are
processed. SiC wear protection for a dosing system with the possibility to dose nano- or picoliter
droplets of water based liquids as well as SiC nanomasking for catalytic agent nanostructures are
demonstrated.
Via Hole Formation in Silicon Carbide by Laser Micromachining
Authors: Zekentes Konstantinos , Zergioti I. , Klini A. , Konstantinidis George
Published: March 2009

A 248 nm (KrF) excimer laser with a repetition rate of 10 Hz, pulse duration of 30 ns and
beam energy up to 450 mJ was employed to form vias in 4H-SiC substrates and Lely platelets. SEM
micrographs have been used to evaluate etched material quality as well as etch rate. The area
surrounding the via-holes is covered by nanoparticles, which are debris from the laser ablation and
are removed by chemical cleaning and agitation. The etch-rate exhibits a perfect linear behaviour
versus the number of laser pulses showing the possibility of an all-laser via-hole formation. A slight
tapering along the via-holes, useful for the subsequent metallization process is also observed.
Finally, a defective,15 μm wide, zone is formed nearby the sidewalls.
Developments in Hybrid Si – SiC Power Modules
Authors: Skibinski G. , Braun D. , Kirschnik D. , Lukaszewski R.
Published: March 2009

This paper investigates utilization of silicon carbide (SiC) Schottky power diodes as
inverter Free Wheel Diodes (FWD) in a commercially available standard Econopak module also
packaged with latest generation low-loss IGBT silicon. Static and switching characteristics of SiC
diodes over standard module operating temperature 25 0C to 125 0C (298 0K - 398 0K) are
measured. Module Turn-on, Turn-off and conduction losses vs. frequency are calculated and
measured for three phase motor drive operation. Measurements are compared to standard modules
using all Silicon (Si) IGBT- diode. System benefits justifying the increased SiC diode cost, such
as EMI reduction, increased efficiency, reduced magnetic filter volume and reduced cooling
requirements at higher allowable switching frequencies is investigated.
Electrothermal Issues in 4H-SiC 600 V Schottky Diodes in Forward Mode: Experimental Characterization, Numerical Simulations and Analytical Modelling
Authors: Irace Andrea , d'Alessandro Vincenzo , Breglio Giovanni , Spirito Paolo , Bricconi Andrea , Carta Rossano , Raffo Diego , Merlin Luigi
Published: March 2009

The electrothermal behavior of 4H-SiC 600 V Schottky diodes operated in forward mode is
analyzed through numerical and analytically-based simulations. It is shown that the unexpected
occurrence of voltage surges systematically detected in state-of-the-art devices is a thermally-induced
effect due to the compound contribution of a) the negative temperature coefficient of the forward
current at high voltages and b) the relatively high package-to-ambient thermal resistance. As a main
result, it is demonstrated that the proposed approaches are suitable to accurately predict the value of a
“critical” current density beyond which voltage surges may arise.
Performance Comparison of 1.5kV 4H-SiC Buried Channel and Lateral Channel JBS Rectifiers
Authors: Zhu Lin , Chow T. Paul , Jones Kenneth A. , Scozzie Charles , Agarwal Anant K.
Published: March 2009

We theoretically and experimentally compare the performance of a new JBS
rectifier structure, the Buried Channel JBS (BC-JBS) rectifier, with that of the Lateral
Channel JBS (LC-JBS) rectifier with 1.5kV blocking capability in 4H-SiC. The BC-JBS
rectifier employs buried p-type regions to create a vertical JFET region to reduce the surface
electric field at Schottky contact during reverse blocking while the LC-JBS rectifier adds a
lateral channel together with the vertical JFET region to protect the surface Schottky interface
during high-voltage blocking conditions. The LC-JBS rectifier offers low reverse leakage
current while the BC-JBS rectifier demonstrates lower specific on-resistance. The optimized
LC-JBS rectifiers show low forward drop (<1.8V) with PiN-like reverse characteristics.
SiC MESFET with a Double Gate Recess
Authors: Nilsson Per Åke , Rorsman Niklas , Südow Mattias , Andersson Kristoffer , Hjelmgren Hans , Zirath Herbert
Published: March 2009

In order to increase the output power and drain efficiency, MESFETs in SiC have been
made with a double gate recess technique. Typical device characteristics of the MESFETs are drain
currents of 380mA/mm, breakdown voltages of 80V and ft/fmax of 10/25 GHz respectively. These
transistors exhibit power densities of 3W/mm@3GHz in class AB operation and drain efficiencies
of 60%. Packaged devices with 3 mm gate periphery of this type, with via-hole grounding, gave
power densities of 1.2 W/mm@6GHz at 50 V drain bias.
The Characteristics of MOSFETs Fabricated on the Trench Sidewalls of Various Faces Using 4H-SiC (11-20) Substrates
Authors: Fujisawa Hiroyuki , Tsuji Takashi , Nishiura Masaharu
Published: March 2009

This paper reports the channel mobilities of MOSFETs formed on the trench sidewalls with
different crystal faces including (0001), (000-1), (1-100) and (0-33-8) using 4H-SiC (11-20)
substrates. Deposited poly-Si was oxidized in wet ambient to form the gate oxide, and annealed in
N2O (10%) ambient. The order of drain current of trench sidewall MOSFETs was (0-33-8) > (1-100)
> (000-1) = (0001). We could gain comparatively high channel mobility on the (0-33-8) face. The
maximum effective channel mobility (μeff) was 35cm2/Vs, and μeff at 2.5MV/cm was 29 cm2/Vs on
the (0-33-8) face.
Reduction of On-Resistance in 4H-SiC Multi-RESURF MOSFETs
Authors: Noborio Masato , Negoro Yuki , Suda Jun , Kimoto Tsunenobu
Published: March 2009

SiC lateral MOSFETs with multi-RESURF structures have been fabricated by a
self-aligned process. The “multi-RESURF” means “double RESURF” and “buried-p RESURF”
structures, which have the buried-p region at the top and at the middle of RESURF region,
respectively. The increase of net RESURF dose and the decrease of channel length lead to the reduced
on-resistance. The “buried-p RESURF” MOSFETs have higher on-resistances than the “double
RESURF” MOSFETs, due to the resistance of parasitic JFET inside the RESURF region. The dose
designing for double RESURF MOSFETs has been optimized by using device simulation. A double
RESURF MOSFET exhibits a breakdown voltage of 750 V and an on-resistance of 52 m/cm2.
Using a First Principles Coulomb Scattering Mobility Model for 4H-SiC MOSFET Device Simulation
Authors: Potbhare Siddharth , Pennington Gary , Goldsman Neil , Lelis Aivars J. , Habersat Daniel B. , McLean F. Barry , McGarrity J.M.
Published: March 2009

A physics based device simulator for detailed numerical analysis of 4H-SiC MOSFETs
with an advanced mobility model that accounts for the effects of bulk and surface phonons, surface
roughness and Coulomb scattering by occupied interface traps and fixed oxide charges, has been
developed. A first principles quasi-2D Coulomb scattering mobility model specifically for SiC
MOSFETs has been formulated. Using this, we have been able to extract the interface trap density
of states profile for 4H-SiC MOSFETs and have shown that at room temperature, Coulomb
scattering controls the total mobility close to the interface. High temperature, low field simulations
and experiments show that the current increases with increase in temperature. The effect of
Coulomb scattering decreases with increase in temperature causing an increase in the total mobility
near the interface at low gate voltages.
High Current 6 kV 4H-SiC PiN Diodes for Power Module Switching Applications
Authors: Hull Brett A. , Das Mrinal K. , Richmond Jim , Heath Bradley , Sumakeris Joseph J. , Geil Bruce , Scozzie Charles
Published: March 2009

Forward voltage (VF) drift, in which a 4H-SiC PiN diode suffers from an irreversible
increase in VF under forward current flow, continues to inhibit commercialization of 4H-SiC PiN
diodes. We present our latest efforts at fabricating high blocking voltage (6 kV), high current (up to
50 A) 4H-SiC PiN diodes with the best combination of reverse leakage current (IR), forward voltage
at rated current (VF), and VF drift yields. We have achieved greater than 60% total die yield onwafer
for 50 A diodes with a chip size greater than 0.7 cm2. A comparison of the temperature
dependent conduction and switching characteristics between a 50 A/6 kV 4H-SiC PiN diode and a
commercially available 60 A/4.5 kV Si PiN diode is also presented.
CM-Wave Modulator with High-Voltage 4H SiC pin Diodes
Authors: Boltovets Mykola S. , Basanets Volodymyr V. , Zorenko A.V. , Krivutsa Valentyn A. , Camara Nicolas , Orechovskij V.O. , Simonchuk V.I. , Zekentes Konstantinos
Published: March 2009

The results of mathematical simulation, development and investigation of a modulator
with 4H SiC pin diodes are presented. We simulated the effect of bias modes on isolation and
transmission between the modulator input and output in the 1−20 GHz frequency range, for pin
diodes with 6 μm long i-region. It was calculated that the isolation in a modulator with three diodes
may run into –45 dB, the transmission losses being no more than 2 dB.
The modulator was made as an integrated circuit (IC) on the basis of nonsymmetrical strip lines
(characteristic impedance of 50 Ω) incorporating chips of high-voltage 4H SiC pin diodes with iregion
6 μm long, mesa diameter of 60 μm and calculated avalanche breakdown voltage of 1000 V.
We studied the experimental parameters of this modulator as a function of forward current and
reverse voltage in the 2.4−12 GHz frequency range, as well as the microwave signal switching
behavior. It was determined that the modulator is characterized by transmission losses of
1.0−2.0 dB and isolation of 27−34 dB (in the 2.4−7 GHz frequency range). The formation of
microwave pulses with leading (trailing) edge of 22 (29) ns was also observed.
Advances in SiC GTO Development and Its Applications
Authors: Sugawara Yoshitaka
Published: March 2009

To achieve large current capability in spite of present small SiC devices that are limited by various
crystal defects, focus was placed on SiC GTO thyristor and SICGT have been developed as an advanced SiC
GTO. SICGTs with current capability of 1.6-100 A and blocking voltage of 3-12.7 kV and a 3 phase PWM
SICGT inverter with output power of 35 kVA have been successfully developed. Furthermore, application
of the SiC inverter aimed to a load leveling system was demonstrated.
First Demonstration of 2.1 kW Output Power at 425 MHz Using 4H-SiC RF Power BJTs
Authors: Agarwal Anant K. , Husna Fatima , Haley Jeremy , Bartlow Howard , McCalpin Bill , Krishnaswami Sumi , Capell Craig , Ryu Sei Hyung , Palmour John W.
Published: March 2009

For the first time, 4H-SiC RF bipolar junction transistors have been used to produce an
output power in excess of 2.1 kW at 425 MHz. For an input pulse width of 2 μs and 1% duty cycle,
the power gain at peak output power is 6.3 dB with the collector efficiency and power added
efficiency [PAE] being 45% and 35%, respectively, at a collector supply voltage of 75 V in a class
C configuration. The package consists of 24 cells (2 chips) having an emitter periphery of
approximately 1 inch per cell. Each cell produced a DC current gain (β) of 15 and a common
emitter breakdown voltage (BVCEO) greater than 250 V. A peak output power of 87 W per cell was
obtained at 425 MHz, as compared to the earlier report of 50 W per cell [1, 2] by using a shorter
pulse width and duty cycle.
Current Gain Dependence on Emitter Width in 4H-SiC BJTs
Authors: Domeij Martin , Lee Hyung Seok , Zetterling Carl Mikael , Östling Mikael , Schöner Adolf
Published: March 2009

This paper reports the fabrication of epitaxial 4H-SiC bipolar junction transistors (BJTs)
with a maximum current gain β=64 and a breakdown voltage of 1100 V. The high β value is
attributed to high material quality obtained after a continuous epitaxial growth of the base-emitter
junction. The current gain of the BJTs increases with increasing emitter width indicating a
significant influence of surface recombination. This “emitter-size” effect is in good agreement with
device simulations including recombination in interface states at the etched termination of the baseemitter
junction.
Improved Structural Quality and Carrier Decay Times in GaN Epitaxy on SiN and TiN Porous Network Templates
Authors: Özgür Ümit , Fu Y. , Litton Cole W. , Moon Y.T. , Yun F. , Everitt H.O. , Morkoç Hadis
Published: March 2009

Improved structural quality and radiative efficiency were observed in GaN thin films
grown by metalorganic chemical vapor deposition on in situ-formed SiN and TiN porous network
templates. The room temperature carrier decay time of 1.86 ns measured for a TiN network sample
is slightly longer than that for a 200 μm-thick high quality freestanding GaN (1.73 ns). The
linewidth of the asymmetric X-Ray diffraction (XRD) (1012) peak decreases considerably with the
use of SiN and TiN layers, indicating the reduction in threading dislocation density. However, no
direct correlation is yet found between the decay times and the XRD linewidths, suggesting that
point defect and impurity related nonradiative centers are the main parameters affecting the lifetime.
Effects of Rapid Thermal Annealing Treatment on the Surface Band Bending of n-type GaN Studied by Surface Potential Electric Force Microscopy
Authors: Chevtchenko S. , Fan Q. , Litton Cole W. , Baski A.A. , Morkoç Hadis
Published: March 2009

It is generally accepted that the Schottky barrier height (SBH) is affected by the initial
band bending at the bare nGaN surface as well as by an additional contribution following metal
deposition. In this work the effect of processing used for device fabrication on the surface band
bending of bare c-plane nGaN was studied by surface potential electric force microscopy (SP-EFM).
An increase of the initial upward band bending from 1.0 ± 0.1eV for the as-grown GaN to 1.9 ±
0.1eV after RTA treatment in N2 ambient was observed. No significant dependence of band bending
on N2 or Ar as ambient gas during the RTA treatment was observed. The increase of the initial
upward band bending was also confirmed by photoluminescence (PL) measurements. We suggest
that the RTA treatment causes a high density of surface states, possibly as a result of high
temperature reaction of ambient gas and remnant contamination.
The Properties of n-ZnO/p-SiC Heterojunctions and their Potential Applications for Devices
Authors: Litton Cole W. , Alivov Ya.I. , Johnstone D. , Özgür Ümit , Avrutin V. , Fan Q. , Akarca-Biyikli S.S. , Zhu K. , Morkoç Hadis
Published: March 2009

Heteroepitaxial n-ZnO films have been grown on commercial p-type 6H-SiC substrates
by plasma-assisted molecular-beam epitaxy, and n-ZnO/p-SiC heterojunction mesa structures have
been fabricated and their photoresponse properties have been studied. Current-voltage
characteristics of the structures had a very good rectifying diode-like behavior with a leakage
current less than 2 x 10-4 A/cm2 at -10 V, a breakdown voltage greater than 20 V, a forward turn on
voltage of ∼5 V, and a forward current of ∼2 A/cm2 at 8 V. Photosensitivity of the diodes, when
illuminated from ZnO side, was studied at room temperature and photoresponsivity of as high as
0.045 A/W at -7.5 V reverse bias was observed for photon energies higher than 3.0 eV.
Role of Oxygen in Growth of Carbon Nanotubes on SiC
Authors: Lu Wei Jie , Boeckl John , Mitchel W.C. , Rigueur J. , Collins W.E.
Published: March 2009

Carbon nanotubes (CNTs) grown on SiC are metal-free, well-aligned, and with low
structural defects. In this study, CNT formation on SiC is examined in high vacuum (10-5torr) and
ultra-high vacuum (10-8torr). Multi-wall carbon nanotubes and graphitic structures are the main
products on the SiC surface at 1400-1800°C in 10-5torr. Under ultra-high vacuum, the
decomposition rate of SiC is much lower than in high vacuum, indicating that SiC is decomposed
by oxidation reaction. Using X-ray photoelectron spectroscopy (XPS), the intensity of the O1s peak
at 530.3 eV decreases with increasing take-off angle, indicating that this oxygen species exists on
the walls of CNTs. The results show that oxygen with a low pressure not only oxidizes SiC, but
also forms a highly thermally stable carbon-oxygen compound, and interacts with the CNTs at high
temperatures.
Origin of the Up-Conversion Process in 4H SiC
Authors: Steeds John W. , Furkert S.A. , Sullivan W. , Wagner Günter
Published: March 2009

The unusual behaviour of two optical centres with zero phonon lines close to 463nm has
been investigated by means of low-temperature photoluminescence microscopy using 488nm and
325nm laser excitation. The experiments were performed on as-irradiated samples and also after
annealing isochronally to various temperatures up to 1300°C.
Cathodoluminescence Measurements and Thermal Activation of Rare Earth Doped (Tb3+, Dy3+ and Eu3+) a-SiC Thin Films Prepared by rf Magnetron Sputtering
Authors: Weingärtner Roland , Erlenbach Oliver , De Zela Francisco , Winnacker Albrecht , Brauer Isabel , Strunk Horst P.
Published: March 2009

We present comprehensive cathodoluminescence measurements from thin amorphous a-
SiC films doped with rare earths. The a-SiC films were prepared by rf magnetron sputtering using a
high purity SiC wafer in high purity argon atmosphere (5N, pressure approx. 0.2 mbar). The rare
earth doping (Tb, Dy and Eu concentrations were below 2%) was performed by placing respective
rare earth metal pieces of appropriate size onto the Silicon Carbide wafer. The rare earth ion
emissions cover the colors green (Tb), yellow (Dy) and red (Eu). The optical and related structural
properties of the films are correlated by means of high resolution transmission electron microscopy
in combination with cathodoluminescence measurements in a scanning electron microscope. In
addition, the corresponding compositions are determined by energy-dispersive x-ray analysis. The
cathodoluminescence spectra of the rare earth 3+ ions are recorded in the visible at 20°C in the asgrown
condition and after annealing treatments in the temperature range from 300°C to 1050°C by
steps of 150°C. The anneal-related changes in the cathodoluminescence emission spectra and in the
microstructure of the films are addressed. The SiC films show amorphous structure almost
independent of the annealing treatment. Optimal annealing temperature for emissions of Tb3+ doped
a-SiC were derived to be 600°C whereas Dy3+ and Eu3+ emissions increase at least up to 1050°C.
Temperature Induced Phase Transformation on the 4H-SiC(11-20) Surface
Authors: Lee W.Y. , Soubatch S. , Starke Ulrich
Published: March 2009

The atomic structure of the 4H-SiC(11 2 0) surface including possible phase
transformations via Si deposition and annealing has been investigated using low energy electron
diffraction (LEED), Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS)
and atomic force microscopy (AFM). The sample is initially prepared by hydrogen etching before
loading into the ultra-high vacuum system. The sample is then out-gassed to remove oxygen from
the surface. To explore the existence of ordered surface phases, Si is deposited on the sample at
850°C for 15 minutes followed by a series of sequential annealing steps. Throughout this process,
the surface is monitored by LEED, AES and XPS. LEED shows that the surface continuously
maintains a (1×1) periodicity. Yet, two unique and distinguishable (1×1) phases can be identified.
The changes between these phases are clearly demonstrated by the LEED spot intensities.
Simultaneously, the Auger and XPS data show a decrease in Si intensity.
Low Energy Ion Modification of 3C-SiC Surfaces
Authors: Förster Christian , Kosiba Ratislav , Ecke Gernot , Cimalla Volker , Ambacher Oliver , Pezoldt Joerg
Published: March 2009

The effects of argon and nitrogen bombardment of 3C-SiC surfaces at acceleration voltages
below 2 keV were studied by stylus profilometry, reflectometry, reflection high energy electron
diffraction and Auger electron spectroscopy (AES). The erosion rate of the SiC surface was
determined. It was found that the sputtering rate for argon was three times higher compared to nitrogen.
AES measurements revealed argon and nitrogen incorporation at a depth of a few nanometers
as well as stoichiometric changes at the same depth scale independent of the acceleration voltage.
In the case of the interaction of nitrogen ions with the 3C-SiC surface the formation of a SiCNalloy
was detected.
Characterization of SiC Wafers by Photoluminescence Mapping
Authors: Tajima Michio , Higashi E. , Hayashi Toshihiko , Kinoshita Hiroyuki , Shiomi Hiromu
Published: March 2009

The effectiveness of room-temperature photoluminescence (PL) mapping was
demonstrated for nondestructive detection of structural defects, such as dislocations, micropipes and
stacking faults, in SiC wafers. PL spectra of bulk wafers were dominated by deep-level emissions
due to Si vacancies, vanadium and undefined centers like UD-1 at room temperature, while those
from epitaxial wafers involved near band-edge emission. We developed a whole-wafer PL intensity
mapping system with a capability of zooming in on the area of interest with a spatial resolution as
high as 1 μm, and showed that the mapping patterns agree well with the etch-pit patterns originating
from the structural defects both on a wafer scale and on a microscopic scale. The intensity contrast
around the defects varied depending on the emission band, suggesting differences in their interactions
with impurities and point defects.
Ion Implantation Processing and Related Effects in SiC
Authors: Svensson Bengt Gunnar , Hallén Anders , Wong-Leung J. , Janson Martin S. , Linnarsson Margareta K. , Kuznetsov Andrej Yu. , Alfieri Giovanni , Grossner Ulrike , Monakhov Edouard V. , K.-Nielsen H. , Jagadish C. , Grillenberger Joachim
Published: March 2009

A brief survey is given of some recent progress regarding ion implantation processing
and related effects in 4H- and 6H-SiC. Four topics are discussed; an empirical ion range distribution
simulator, dynamic defect annealing during implantation, formation of highly p+-doped layers, and
deactivation of N donors by ion-induced defects.
Annealing Behavior of N+-Implantation-Induced Defects in SiC at Low Temperatures
Authors: Satoh Masataka , Suzuki Tomoyuki , Miyagawa Shohei
Published: March 2009

The annealing behavior of the N+ implantation-induced defects in 4H-SiC(0001) has
been investigated by means of Rutherford backscattering spectrometry in the annealing
temperature range from 200 to 1000 oC. The samples are multiple-implanted by N+ ions with
energy range from 15 to 120 keV at a total dose of 2.4 x 1015 /cm2. Three annealing stages are
observed by isochronal annealing; first stage from 200 to 400 oC, second stage from 400 to 600 oC
and third stage from 600 to 1000 oC. The 80 percent of the N+ implantation-induced defects are
annealed out at the temperature above 600 oC. The annealing mechanism of the defects in each
stage is discussed.
Activation Treatment of Ion Implanted Dopants Using Hybrid Super RTA Equipment
Authors: Kinoshita Akimasa , Senzaki Junji , Katou Makoto , Harada Shinsuke , Okamoto Mitsuo , Nishizawa Shin Ichi , Fukuda Kenji , Morigasa Fukuyoshi , Endou Tomoyoshi , Isii Takuo , Yashima Teruyuki
Published: March 2009

We perform rapid thermal annealing (RTA) on areas as large as 2-inch φ (diameter) at
high temperature using the hybrid super RTA (HS-RTA) equipment. The HS-RTA equipment
consists of an infrared annealing unit and a RF induction annealing unit in order to uniformly anneal
over 2-inch φ susceptor. As a result of annealing by the HS-RTA equipment, the temperature is
elevated from RT to peak temperature (~1800°C) for less than 1 min, remain stable at annealing
temperature for 30s and falls from peak temperature to 1000°C within less than 20s. The
temperature distributions on a 2-inch φ susceptor are ±10°C, ±33°C and ±55°C at 1565°C,
1671°C and 1752°C, respectively. Phosphorus (P) ion implanted silicon carbide (SiC) samples are
used to evaluate the performance of the HS-RTA equipment. The five implanted samples placed on
the 2-inch φ susceptor are annealed for 30s at 1565°C, 1671°C and 1752°C. The mean sheet
resistances of the 5 samples annealed at 1565°C, 1671°C and 1752°C are 92.6Ω/, 82.6Ω/ and
75.5Ω/, respectively. The sheet resistance uniformities are 9.9%, 7.9% and 9.3%. The average
roughness (Ra) is calculated from 10 μm square Atomic Force Microscopy (AFM) image. Ra values
of the samples annealed at 1565°C, 1671°C and 1752°C are 2.399 nm, 2.408 nm and 3.282 nm,
respectively.
Development and Investigation on EBAS-100 of 100 mm Diameter Wafer for 4H-SiC Post Ion Implantation Annealing
Authors: Shibagaki Masami , Satoh Masataka , Kurematsu Yasumi , Numajiri Kenji , Watanabe Fumio , Haga Shigetaka , Miura Kuniaki , Suzuki Tomoyuki , Miyagawa Shohei
Published: March 2009

We developed EBAS-100, which is available to 100 mm diameter SiC wafer, for post ion
implantation annealing in order to realize silicon carbide (SiC) device with large volume production.
EBAS-100 is able to perform the rapid thermal process due to the vacuum thermal insulation and
small heat capacity of susceptor. Electrical power consumption density was 18.8 Wh/cm2 for
EBAS-100, which is one-third smaller than that of our previous system (EBAS-50). Samples used in
this study were p-type epitaxial 4H-SiC (0001) grown on 8o off SiC substrate. P+ ions (total dose; 2.0 x
1016 /cm2, thickness; 350 nm) were implanted into SiC samples at 500 oC. The root-mean-square
(RMS) of surface roughness is estimated to be 0.21 nm for the sample annealed at 1700 oC for 5 min,
which is much smooth than that of the sample annealed by the conventional RF inductive annealing
(RMS value: 5.97 nm). Averaged sheet resistance (RS) value of 63.3 ohm/sq. is obtained with the
excellent non-uniformity of RS (+/- 1.4 %) for the diameter of 76.0 mm.