bluuebunny/crossref_metadata_2025 huggingface dataset:
4.3 mΩcm2, 1100 V 4H-SiC Implantation and Epitaxial MOSFET
Authors: Harada Shinsuke , Kato Makoto , Okamoto Mitsuo , Yatsuo Tsutomu , Fukuda Kenji , Arai Kazuo
Published: March 2009

The channel mobility in the SiC MOSFET degrades on the rough surface of the p-well
formed by ion implantation. Recently, we have developed a double-epitaxial MOSFET
(DEMOSFET), in which the p-well comprises two stacked epitaxially grown p-type layers and an
n-type region between the p-wells is formed by ion implantation. This device exhibited a low
on-resistance of 8.5 mcm2 with a blocking voltage of 600 V. In this study, to further improve the
performance, we newly developed a device structure named implantation and epitaxial MOSFET
(IEMOSFET). In this device, the p-well is formed by selective high-concentration p+ implantation
followed by low-concentration p- epitaxial growth. The fabricated IEMOSFET with a buried channel
exhibited superior characteristics to the DEMOSFET. The extremely low specific on-resistance of 4.3
mcm2 was achieved with a blocking voltage of 1100 V. This value is the lowest in the normally-off
SiC MOSFETs.
Fabrication of 4H-SiC p-Channel MOSFET with High Channel Mobility
Authors: Okamoto Mitsuo , Tanaka Mieko , Yatsuo Tsutomu , Fukuda Kenji
Published: March 2009

We have fabricated inversion-type p-channel MOSFETs on 4H-SiC substrates. In this
paper, influences of gate oxidation process on the properties of p-channel MOSFETs were
investigated. The gate oxide was formed under these three conditions: (i) dry oxidation, (ii) dry
oxidation following wet re-oxidation, and (iii) wet oxidation. The C-V measurements of p-type
4H-SiC MOS capacitors revealed that wet oxidation process reduced the interface states near the
valence band. The p-channel MOSFET with low interface states near the valence band indicated low
threshold voltage (Vth), high field effect channel mobility (μFE) and low subthreshold swing (S). We
obtained 4H-SiC p-channel MOSFET with high μFE of 15.6cm2/Vs by using wet oxidation as gate
oxidation process.
Charge Induced in 6H-SiC PN Diodes by Irradiation of Oxygen Ion Microbeams
Authors: Ohshima Takeshi , Satoh Takahiro , Oikawa Masakazu , Onoda Shinobu , Hirao Toshio , Itoh Hisayoshi
Published: March 2009

The charge generated in 6H-SiC n+p diodes by oxygen (O) ion irradiation at energies
between 6 and 15 MeV was evaluated using the Transient Ion Beam Induced Current (TIBIC). The
signal peak of the transient current increases, and the fall-time decreases with increasing applied
reverse bias. The value of collected charge increases with increasing applied reverse bias, and the
saturation of the collected charge was observed in high reverse bias regions (e.g. above 70 V in the
case of 12MeV O-irradiation). The charge generated in the deeper region than the depletion layer is
collected due to the "funneling effect". Almost all charge generated in n+p SiC diodes by O-irradiation
between 6 and 15 MeV is collected when the length of the depletion layer becomes longer than the
projection range of ions.
Challenges in Large-Area Multi-Wafer SiC Epitaxy for Production Needs
Authors: Thomas Bernd , Hecht Christian , Stein René A. , Friedrichs Peter
Published: March 2009

The rapid market development for SiC-devices during the last years can be attributed
particularly to the success in supplying high-quality SiC wafers and corresponding epitaxial layers.
The device quality could be enhanced and the costs were reduced by enlarging the wafer size as
well as by a significant progress in epitaxial growth of active layers by using multi-wafer CVD systems.
In this paper we want to give an overview of CVD multi-wafer systems used for SiC growth
in the past and today. We present recent results of SiC homoepitaxial growth using our multi-wafer
hot-wall CVD system. This equipment exhibits a capacity of 5×3” wafers per run and can be upgraded
to a 7×3” or 5×4” setup. By optimizing the process conditions epitaxial layers with excellent
crystal quality, purity and homogeneity of doping and thickness have been grown. Issues like reproducibility,
drift of parameters and system stability over several runs will be discussed.
Characteristics and Ionization Coefficient Extraction of 1kV 4H-SiC Implanted Anode PiN Rectifiers with Near Ideal Performance Fabricated Using AlN Capped Annealing
Authors: Zhu Lin , Losee Peter A. , Chow T. Paul , Jones Kenneth A. , Scozzie Charles , Ervin Matthew H. , Shah Pankaj B. , Derenge Michael A. , Vispute R.D. , Venkatesan T. , Agarwal Anant K.
Published: March 2009

4H-SiC PiN rectifiers with implanted anode and single-zone JTE were fabricated using
AlN capped anneal. The surface damage during the high temperature activation anneal is
significantly reduced by using AlN capped anneal. The forward drop of the PiN rectifiers at
100A/cm2 is 3.0V while the leakage current is less than 10-7A/cm2 up to 90% breakdown voltage at
room temperature. With 6μm thick and 2×1016cm-3 doped drift layer, the PiN rectifiers can achieve
near ideal breakdown voltage up to 1050V. Hole impact ionization rate was extracted and
compared with previously reported results.
Demonstration of High-Voltage 4H-SiC Bipolar RF Power Limiter
Authors: Su Ming , Xin Xiao Bin , Li Larry X. , Zhao Jian Hui
Published: March 2009

We present the design and fabrication of the first high-voltage 4H-SiC RF power limiter.
First, Schottky and PiN diodes are compared for power limiter applications by numerical simulations.
Small-signal S-parameters and large-signal operation are then simulated based on our device design.
The fabrication is based on a SiC PiN diode with at least 900V blocking capability and packaged into
a 50 microstrip transmission line fixture. Small signal insertion and return losses are measured in
the frequency band from 100MHz to 3GHz after packaging and agree well with our simulation. The
limiter has an insertion loss of only 0.6dB at 1GHz. This is believed to be the first 4H-SiC
high-voltage RF power limiter, as well as one of the best SiC limiters in terms of low small-signal
transmission loss up to gigahertz frequencies.
1836 V, 4.7 mΩ•cm2 High Power 4H-SiC Bipolar Junction Transistor
Authors: Zhang Jian Hui , Wu Jian , Alexandrov Peter , Burke Terry , Sheng Kuang , Zhao Jian Hui
Published: March 2009

This paper reports recent progress in the development of high power 4H-SiC BJTs based
on an improved device design and fabrication scheme. Near theoretical limit high blocking voltage
of VCEO=1,836 V has been achieved for 4H-SiC BJTs based on a drift layer of only 12 μm, doped to
6.7x1015 cm-3. The collector current measured for a single cell BJT with an active area of 0.61 mm2
is up to IC=9.87 A (JC=1618 A/cm2). The collector current is 7.64 A (JC=1252 A/cm2) at VCE=5.9 V
in the saturation region, corresponding to an absolute specific on-resistance (RSP_ON) of 4.7 m9·cm2.
From VCE=2.4 V to VCE= 5.8 V, the BJT has a differential RSP_ON of only 3.9 m9·cm2. The current
gain is about 8.8 at Ic=5.3 A (869 A/cm2). This 4H-SiC BJT shows a V2/RSP_ON of 717 MW/cm2,
which is the highest value reported to date for high-voltage and high-current 4H-SiC BJTs. A verylarge
area 4H-SiC BJT with an active area of 11.3 mm2 is also demonstrated.
Device Options and Design Considerations for High-Voltage (10-20 kV) SiC Power Switching Devices
Authors: Sui Yang , Walden Ginger G. , Wang Xiao Kun , Cooper James A.
Published: March 2009

We compare the on-state characteristics of five 4H-SiC power devices
designed to block 20 kV. At such a high blocking voltage, the on-state current
density depends heavily on the degree of conductivity modulation in the drift region,
making the IGBT and thyristor attractive devices for high blocking voltages.
Novel Power Si/4H-SiC Heterojunction Tunneling Transistor (HETT)
Authors: Hayashi Tetsuya , Shimoida Yoshio , Tanaka Hideaki , Yamagami Shigeharu , Tanimoto Satoshi , Hoshi Masakatsu
Published: March 2009

We demonstrate a novel power Si/4H-SiC heterojunction tunneling transistor (HETT) on
the basis of theoretical analysis and experimental results. The HETT is an insulated gate drive device
and has a unique switching mechanism. In the off-state, the heterojunction barrier prevents current
flow between the Si source region and the 4H-SiC drift region. In the on-state, the width of the
heterojunction barrier is controlled by the gate bias to allow tunneling current to flow. The HETT has
a zero channel length structure that is more independent of channel mobility compared with a
conventional 4H-SiC MOSFET. As a result, the HETT is expected to have low on-resistance.
A HETT was fabricated with n+-type polycrystalline silicon on an n--type 4H-SiC epitaxial wafer
for power devices. The fabricated HETT shows a low specific on-resistance of 6.8 mcm2 (at Jd=500
A/cm2).
Silicon Carbide Power Diodes as Radiation Detectors
Authors: Phlips Bernard F. , Hobart Karl D. , Kub Francis J. , Stahlbush Robert E. , Das Mrinal K. , De Geronimo Gianluigi , O' Connor Paul
Published: March 2009

We have tested the radiation detection performance of Silicon Carbide (SiC) PIN diodes
originally developed as high power diodes. These devices consist of 100 micron thick SiC grown
epitaxially on SiC substrates. The size and thickness of the devices make them appropriate for a
number of radiation detection applications. We tested 0.25 cm2 and 0.5 cm2 devices and obtained
X-ray spectra under illumination with an Am-241 radioactive source. The spectra showed an energy
resolution that was consistent with the resolution expected for the large capacitance of the device.
Smaller devices with a diameter of 1 mm were also tested and produced spectra with a room
temperature energy resolution of ~550 eV, which is consistent with the electronics limit for the
capacitance of the small device. We measured the absolute charge generated by X-rays per KeV in
SiC by comparing the charge generation with similar silicon devices and determined the energy
required per electron hole pair in SiC to be 8.4 eV. We also performed radiation damage tests on
these devices and found no significant loss in charge collection up to a photon dose of 100 MRad.
Applications for these devices can be found in the fields of particle physics, nuclear physics,
nuclear medicine, X-ray fluorescence, X-ray astronomy and X-ray navigation.
The Limit of SiC Detector Energy Resolution in Ion Spectometry
Authors: Yakimova Rositza , Lebedev Alexander A. , Ivanov Alexander M. , Strokan Nikita B. , Syväjärvi Mikael
Published: March 2009

A full modeling of deceleration of α-particles in SiC is carried out using a Monte-Carlo
method. The distribution of energy losses in nuclear elastic collisions is calculated. The spectrum
has a characteristic asymmetric form and the line width at half peak maximum is 4.62 keV. The
final form of a spectral line is obtained by convolution with a Gaussian peak, and including the
contribution of ionization fluctuations and noise. The resulting value of the line width was 8.75 keV
(at a noise dispersion of detector and equipment of 1.7 keV). The resolution of detectors reached in
practice is twice the lowest calculated value. It is shown that charge losses during transport of nonequilibrium
carriers through the volume of the detector are insignificant, while a resolution
divergence may result from a non-optimized “entrance window”.
Surface Morphology of GaN Films Grown by RF-Plasma MBE Using Lateral Overgrowth and Low-Temperature Ga-rich Condition
Authors: Shimizu Mitsuaki , Chonan Hiroshi , Piao Guaxi , Okumura Hajime , Nakanishi Hisayuki
Published: March 2009

In order to improve the crystal quality of MBE-grown GaN layers we employed a high
temperature growth process and enhanced the lateral overgrowth. The grain size of the GaN layer was
enlarged up to 2 "m in diameter. Significant improvement in the XRD characteristics was found, and
the FWHM value of the asymmetric (10-12) XRD ω-scan peak became less than 400 arcsec when the
layer thickness was 3 "m. Further, to planarise the surface, the low temperature gallium-rich growth
process was employed and the large grooves between the grains vanished.
The Effect of Aluminum Nitride-Silicon Carbide Alloy Buffer Layers on the Sublimation Growth of Aluminum Nitride on SiC (0001) Substrates
Authors: Gu Z. , Edgar J.H. , Raghothamachar Balaji , Dudley Michael , Zhuang Dejin , Sitar Zlatko
Published: March 2009

The benefits of depositing AlN-SiC alloy transition layers on SiC substrates before the
seeded growth of bulk AlN crystals were determined. The presence of the AlN-SiC alloy layer
helped to suppress the SiC decomposition by providing vapor sources of silicon and carbon. It
enabled a higher growth temperature, and hence a higher growth rate. In addition, cracks in the
final AlN crystals can be decreased because of the intermediate lattice constants and thermal
expansion coefficient of AlN-SiC alloy. AlN-SiC alloys were first grown on off-axis SiC substrates
by the sublimation-recondensation method. Then pure AlN crystals were grown upon those. For
comparison, AlN crystals were directly grown on SiC substrates under similar conditions. X-ray
diffraction (XRD) confirmed the formation of a pure single crystalline AlN layer upon the AlN-SiC
alloy on SiC substrate. The presence of an AlN-SiC transition layer effectively inhibited the
appearance of cracks in the resultant AlN crystals. X-ray topography (XRT) demonstrated that the
thick AlN layer effectively released the strain present.
Structural and Electrical Characteristics of Carbon Nanotubes Formed on Silicon Carbide Substrates by Surface Decomposition
Authors: Boeckl John , Mitchel W.C. , Lu Wei Jie , Rigueur J.
Published: March 2009

Aligned carbon nanotubes (CNT’s) are formed on the surface of silicon carbide (SiC)
wafers during high temperature anneals. The exposed 4H SiC surface transforms into CNT’s for
temperatures in the range of 1400-1700°C and under moderate vacuum conditions (10-2
– 10-5
torr).
The rate of formation on the C-face (0001,‾) is about three times the rate on the Si-face (0001), but
both rates increase with anneal temperature. SEM, TEM and Raman scattering measurements have
confirmed the presence of both single-wall and multi-wall CNT’s. The carbon source is believed to
be residual carbon from the SiC left on the surface after preferential evaporation of Si. CNT
formation is believed to be catalyzed by low concentrations of residual oxygen in the chamber.
Subsequent I-V measurements provide insight into the electrical characteristics of the CNT’s and
the SiC/CNT interface.
High Epitaxial Growth Rate of 4H-SiC Using Horizontal Hot-Wall CVD
Authors: Myers-Ward Rachael L. , Shishkin Y. , Kordina Olof , Haselbarth I. , Saddow Stephen E.
Published: March 2009

A 4H-SiC epitaxial growth process has been developed in a horizontal hot-wall CVD
reactor using a standard chemistry of silane-propane-hydrogen, producing repeatable growth rates
up to 32 μm/h. The growth rate was studied as a function of pressure, silane flow rate, and growth
time. The structural quality of the films was determined by X-ray diffraction. A 65 μm thick
epitaxial layer was grown at the 32 μm/h rate, resulting in a smooth, specular film morphology with
occasional carrot-like and triangular defects. The film proved to be of high structural quality with
an X-ray rocking curve FWHM value of the (0004) peak of 11 arcseconds.
Highly Uniform SiC Epitaxy for MESFET Fabrication
Authors: Zhang Jie , Mazzola Janice , Hoff Carl , Rivas C. , Romano Esteban , Casady Janna R. B. , Mazzola Michael S. , Casady Jeff B. , Matocha Kevin
Published: March 2009

This paper presents SiC CVD epitaxy for MESFET fabrication in a horizontal hot-wall
reactor with gas foil rotation. Excellent uniformity of < 2% for thickness and < 10% for doping has
been routinely obtained for both 3x2-in. and 1x3-in. growth. The highly uniform epitaxy is
maintained for the growth of a large range of doping concentrations (less than 5x1015 to greater than
1.5x1019 cm-3) and thicknesses (0.25 – 60 μm). MESFET buffer/channel structure has been
characterized with SIMS measurement showing sharp interface transition. Pinch-off voltages are
extracted from CV measurements over a full 2-in. wafer.
High Purity SiC Epitaxial Growth by Chemical Vapor Deposition Using CH3SiH3 and C3H8 Sources
Authors: Hatayama Tomoaki , Yano Hiroshi , Uraoka Yukiharu , Fuyuki Takashi
Published: March 2009

The epitaxial growth of SiC by a hot-wall CVD system using monomethylsilane (CH3SiH3)
as a precursor is described. In the case of CH3SiH3 source only, an undoped homoepitaxial layer
showed an n-type conduction around 1016-1017cm-3 on the Si face. To improve the quality of
epilayers, the simultaneous supply of CH3SiH3 and C3H8 was carried out. The pit density of grown
layers was reduced from 105 to 103cm-2, and a donor concentration as low as 1.6×1014cm-3 was
achieved. An attempt to increase of the growth rate was also investigated.
Proposal of the Thermal Equilibrium Model for SiC Hydrogen Etching Phenomena
Authors: Ishida Yuuki , Takahashi Tetsuo , Okumura Hajime , Arai Kazuo , Kimura K. , Nakamura K. , Yoshida Sadafumi
Published: March 2009

We have proposed a novel model of hydrogen etching of SiC based on thermal
equilibrium and have confirmed the validity of our model through the analysis of H2 etching
experiments. The experimental results obtained showed that the etching rate is expressed by a linear
equation with the H2 flow rate, by an exponential function with the reciprocal of the temperature
and by a power law with the pressure. These results agree well with the theoretical behaviors
derived from our model.
Using Vapour-Liquid-Solid Mechanism for SiC Homoepitaxial Growth on on-axis α-SiC (0001) at Low Temperature
Authors: Soueidan Maher , Ferro Gabriel , Cauwet François , Mollet L. , Jacquier Christophe , Younes Ghassan , Monteil Yves
Published: March 2009

The vapour-Liquid-Solid mechanism was used for growing epitaxial SiC layers on onaxis
6H-SiC and 4H-SiC substrates. By feeding Al70Si30 melts with propane, homoepitaxial growth
was demonstrated down to 1100°C on both polytypes. At this temperature, the surface morphology
is rough and non uniform with spiral growth forming large hillocks at the places where screw
dislocations emerge from the substrate. Raman spectroscopy confirms the absence of the 3C-SiC
polytype and shows the high Al doping of the layers. This growth temperature of 1100°C is the
lowest one ever reported for growing homoepitaxial layers on low tilt angle SiC substrates.
Increasing the temperature to 1200°C eliminates these hillocks but creates other morphological
features due to fast substrate etching at this high temperature before growth starts.
Single-Domain 3C-SiC Epitaxially Grown on 6H-SiC by the VLS Mechanism
Authors: Soueidan Maher , Ferro Gabriel , Stoemenos J. , Polychroniadis Efstathios K. , Chaussende Didier , Soares F. , Juillaguet Sandrine , Camassel Jean , Monteil Yves
Published: March 2009

Using the Vapor-Liquid-Solid mechanism in Ge-Si melts we have grown 3C-SiC
layers on top of <0001>-oriented, Si face, 6H-SiC substrates. The surface morphology was
free of spiral growth but highly step bunched. The 3C-SiC polytype was identified by micro-
Raman spectroscopy and confirmed by low temperature photoluminescence. Electron
backscattering diffraction mapping showed that the upper side of the layers is single-domain,
i.e. that the 3C-SiC material displays only one in-plane orientation. Cross-sectional and planeview
TEM investigations allowed detection of double positioning boundaries but only
confined at the substrate/epilayer interface. The main additional defects found were stacking
faults (SF) with a density of ~ 4.103 cm-1. Forming at the interface, they propagate through the
epitaxial layer.
Reduction of Dislocations in the Bulk Growth of SiC Crystals
Authors: Nakamura Daisuke
Published: March 2009

Recent reports on the impact of elementary dislocations on device performance and
reliability suggest not only micropipe defects but also dislocations should be reduced or eliminated
perfectly. This paper presents bulk growth process for reduction of the dislocations, and quality of the
crystals grown by the process. Etch pit density of the best crystals grown by the process was lower by
three orders of magnitude than that of conventional crystals. Moreover, large diameter crystals (>2”)
with low dislocation density were successfully grown by the process.
Peierls Barriers and Core Properties of Partial Dislocations in SiC
Authors: Savini G. , Heggie M.I. , Öberg Sven
Published: March 2009

First-principles calculations are used to investigate the partial dislocations in 4H-SiC. We
show that the stability of the dislocation cores and the Peierls barriers of the first kind are chargestate
dependent. In intrinsic bulk the partials are stable in the neutral asymmetric reconstructions.
These reconstructions have no deep states and are characterized by high Peierls barriers. In strongly
doped regime the symmetric reconstructions can become more stable. These reconstructions are
always electrically active with a half filled band across the band gap. In particular the symmetric
reconstructions of the 30° partial have a lower Peierls barriers than the respective asymmetric ones
and could be the cause of the 1.8 eV electroluminescence peak observed under carrier injection
conditions.
Characterization of Stacking Fault-Induced Behavior in 4H-SiC p-i-n Diodes
Authors: Wang Y. , Chen L. , Mikhov M.K. , Samson G. , Skromme B.J.
Published: March 2009

Formation of I1 Shockley stacking faults by recombination-enhanced defect glide in 4HSiC
p-i-n diodes subject to high forward current stress is studied in diodes on both c-oriented and aoriented
substrates. The forward voltage increases during stressing for both orientations,
accompanied by nucleation and expansion of faults visible in electroluminescence (EL) imaging.
Low temperature photoluminescence (PL) measurements on degraded diodes of both orientations
reveal the same set of exciton peaks, confirming that the electronic structure of the faults is the
same in both cases. The spectroscopic data are compared to self-consistent solutions of the
Schrödinger and Poisson equations including polarization charge. Dislocations nucleating the
faults are bright in EL images but dark in electron beam-induced current (EBIC) imaging,
confirming that they are sites of enhanced radiative recombination.
Recombination Behaviour of Stacking Faults in SiC p-i-n Diodes
Authors: Maximenko S.I. , Pirouz P. , Sudarshan Tangali S.
Published: March 2009

In this paper the electrical activity of stacking faults and that of their bounding partial
dislocations in degraded PiN diodes has been investigated by the technique of electron beam
induced current (EBIC). The recombination behavior of C- and Si-core dislocations is discussed. It
is proposed that nonradiative recombination significantly exceeds radiative recombination on both
the C- and Si-core partial dislocations. At the same time, predominantly radiative recombination
takes place in the faulted planes that presumably act as quantum wells.
Origin of Surface Morphological Defects in 4H-SiC Homoepitaxial Films
Authors: Okada Tatsuya , Okamoto Kouichi , Ochi Kengo , Higashimine Kouichi , Kimoto Tsunenobu
Published: March 2009

Plan-view transmission electron microscopy (TEM) was applied to investigate the origin of
surface defects in 4H-SiC homoepitaxial films. Their origin existed at the substrate/epi-film interface.
Hence, almost the entire thickness of the epi-film was removed by plasma etching leaving a very thin
film. Then, the etched epi-crystal was thinned from the substrate side so that we could observe the
crystallographic imperfections at the substrate/epi-film interface in plan-view TEM. Morphological
features of the epi-film surface remained unchanged after the plasma etching process. Hence,
one-to-one correspondence between surface defects and crystallographic imperfections was
confirmed by comparing optical micrographs and TEM images. Crystallographic imperfections
associated with “carrot defects” were observed. They were composed of stacking faults on the (0001)
plane and partial dislocations bounding them. These imperfections originated from foreign particles
at the interface. From X-ray energy-dispersive spectrometry (XEDS), it was confirmed that particles
contained zirconium (Zr). Selected area diffraction patterns showed that the particles were
crystalline.
Structure of “Star” Defect in 4H-SiC Substrates and Epilayers
Authors: Lee Jae Won , Skowronski Marek
Published: March 2009

The structure of the “star” defect in 4H-SiC substrates and its effects on the extended defect
structures in the epilayers were studied by molten KOH etching and transmission x-ray topography.
Star defects consist of a center region with high densities of threading dislocations (both edge and
screw types) and six arms of dislocation arrays extending along <11-20> directions. In addition,
multiple linear dislocation arrays extending perpendicular to the off-cut direction were observed in
the epilayers. Dislocation arrays extending along <11-20> directions are consistent with the slip
bands generated by the prismatic slip: a/3<11-20>{1-100}. Bands of linear dislocation arrays
extending perpendicular to the off-cut direction correspond to the threading edge dislocations
nucleated during epitaxial growth.
Growth and Characterization of Large Diameter 6H and 4H SiC Single Crystals
Authors: Gupta A. , Semenas E. , Emorhokpor Ejiro , Chen J. , Zwieback Ilya , Souzis Andrew E. , Anderson Thomas
Published: March 2009

Over the past year, II-VI has transitioned from 2” to 3” commercial SiC
substrates. Large-diameter semi-insulating 6H-SiC and n-type 4H-SiC single crystals are
grown using the Advanced PVT growth process. Expansion of boule diameter from 2 to 3
and up to 4.25 inches has been carried out using a specially designed growth technique.
Stable semi-insulating properties in 6H-SiC are achieved by precise vanadium compensation.
The technique of compensation is optimized to produce a controlled and spatially uniform
distribution of vanadium and high and spatially uniform electrical resistivity reaching 10
10
–
1011 ·cm. N-type 3-inch 4H-SiC crystals are grown using doping with nitrogen, and 3-inch
4H-SiC substrates show uniform resistivity of about 0.018 ·cm. The best quality semiinsulating
(SI) 3” 6H-SiC substrates demonstrate micropipe density of 3 cm-2, and n-type 3”
4H-SiC substrates - about 1 cm-2. X-ray rocking curve topography of the produced 3” SiC
substrates is used for evaluation of their crystal quality.
Structural Defects and Critical Electric Field in 3C-SiC
Authors: Capano Michael A. , Smith A.R. , Kim Byeung C. , Kvam E.P. , Tsoi S. , Ramdas A.K. , Cooper James A.
Published: March 2009

3C-SiC p-type epilayers were grown to thicknesses of 1.5, 3, 6 and 10 μm on 2.5° off-axis
Si(001) substrates by chemical vapor deposition (CVD). Silane and propane were used as precursors.
Structural analysis of epilayers was performed using transmission electron microscopy (TEM),
high-resolution x-ray diffractometry (HRXRD), and Raman spectroscopy. TEM showed defect
densities (stacking faults, twins and dislocations) decreasing with increasing distance from the SiC/Si
interface as the lattice mismatch stress is relaxed. This observation was corroborated by a monotonic
decrease in HRXRD peak width (FWHM) from 780 arcsecs (1.5 μm thick epilayer) to 350 arcsecs (10
μm thick epilayer). Significant further reduction in x-ray FWHM is possible because the minimum
FWHM detected is greater than the theoretical FWHM for SiC (about 12 arcsecs). Raman
spectroscopy also indicates that the residual biaxial in-plane strain decreases with increasing epilayer
thickness initially, but becomes essentially constant between 6 and 10 μm. Structural defect density
shows the most significant reduction in the first 2 μm of growth. Phosphorus implantation was used
to generate n+/p junctions for the measurement of the critical electric field in 3C-SiC. Based on
current-voltage analyses, the critical electric field in p-type 3C-SiC with a doping of 2x1017 cm-3 is
1.3x106 V/cm.
Giant Burgers Vector Micropipe-Dislocations in Silicon Carbide Investigated by Atomic Force Microscopy
Authors: Pernot Etienne , Härtwig J. , Pons Michel , Madar Roland
Published: March 2009

Recently, in some silicon carbide single crystals, some micropipes associated with
screw dislocation have been observed by X-ray topography and the strain field around them
produced images similar to those of screw dislocations with a very large Burgers vector, about
667 nm. The radius of the hole in the centre of the micropipe is less than 10 'm. This value
and the theoretical predictions by Frank (about 7.8 mm) using the Burgers vector magnitude
show a large discrepancy. In this paper we present Atomic Force Microscopy experiments
around this kind of defects. The Burgers vector magnitude of the screw dislocation and the
value of the radius have been measured by this technique. Not only one dislocation, but
several have been observed around the micropipe. We concluded that it is in better agreement
with the Frank theory modified by Cabrera and Levine concerning kinetic effects during the
growth.
Open Core Dislocations and Surface Energy of SiC
Authors: Maximenko S.I. , Pirouz P. , Sudarshan Tangali S.
Published: March 2009

More than fifty years ago Frank proposed that a dislocation with a Burgers vector larger
than a critical value would have an open core. Since then, there has been controversy as to whether
micropipes in SiC are examples of open core screw dislocations. In this work open core dislocations
in 4H-SiC material are investigated by AFM. The results are interpreted on the basis of Frank’s
theory and the surface energy of SiC is estimated from the critical value of Burgers vector. Finally,
the extracted surface energy is compared with the results of other research.
Comparison between Measurement Techniques Used for Determination of the Micropipe Density in SiC Substrates
Authors: Emorhokpor Ejiro , Carlson E.P. , Wan Jian Wei , Weber Arnd Dietrich , Basceri C. , Jenny Jason R. , Sandhu R. , Oliver James D. , Burkeen F. , Somanchi A. , Velidandla V. , Orazio F. , Blew A. , Goorsky M.S. , Dudley Michael , Vetter William M.
Published: March 2009

Micropipe density (MPD) is a crucial parameter for silicon carbide (SiC) substrates
that determines the quality, stability and yield of the semiconductor devices built on these
substrates. The importance of MPD is underscored by the fact that all existing specifications for
6H- and 4H-SiC substrates set upper limits for it. Several methods for measuring the MPD are
known, however, their reliability and applicability to various types of substrates (e.g. semiinsulating,
conducting, etc.) has not been systematically studied.
The subject of this paper is a comparative study of various techniques used for the MPD
measurement accompanied by statistical analysis of the results. The study was initiated by several
organizations working in the immediate field of silicon carbide or in closely related fields and
included SiC substrate manufacturers, substrate consumers, equipment manufacturers and
universities. The study represented a round robin experiment in which MPD was measured on
thirty SiC wafers of various pedigrees. The values of MPD have been determined using both
destructive and non-destructive techniques. The repeatability of each technique is analyzed and
compared with that of other techniques.
High Energy Local Vibrational Modes of Carbon Aggregates in SiC: Experimental and Theoretical Insight
Authors: Mattausch Alexander , Bockstedte M. , Pankratov Oleg , Steeds John W. , Furkert S.A. , Hayes J.M. , Sullivan W. , Wright Nicolas G.
Published: March 2009

We observe new photoluminescence centers in electron-irradiated 6H-SiC with phonon
replicas up to 250 meV and clear threefold isotope splitting of the highest energy mode. Based on ab
initio calculations, we discuss the tri-carbon anti-site (C3)Si and the di-interstitial (C2)Hex as models
for these centers.
Growth of SiC Boules with Low Boron Concentration
Authors: Fanton Mark A. , Cavalero R.L. , Ray R.G , Weiland B.E. , Everson W.J. , Snyder David , Gamble Rick D. , Oslosky Ed
Published: March 2009

The effects of growth conditions, diffusion barrier coatings, and hot zone materials
on B incorporation in 6H-SiC crystals grown by physical vapor transport (PVT) were evaluated.
Development of high purity source material with a B concentration less than 1.8x1015 atoms/cm3,
was critical to the growth of boules with a B concentration less than 3.0x1016 atoms/cm3.
Application of refractory metal carbide coatings to commercial graphite to serve as boron diffusion
barriers and the use of very high purity pyrolytic graphite components ultimately led to the growth
of SiC boules with boron concentrations as low as 2.4x1015 atoms/cm3. The effect of growth
temperature and pressure were closely examined over a range from 2100°C to 2300°C and 5 to 13.5
Torr. This range of growth conditions and growth rates had no effect on B incorporation. Attempts
to alter the gas phase stoichiometry through addition of hydrogen gas to the growth environment
also had no impact on B incorporation. These results are explained by considering site competition
effects and the ability of B to diffuse through the graphite growth cell components.
A Combined Photoluminescence and Electron Paramagnetic Resonance Study of Low Energy Electron Irradiated 4H SiC
Authors: Sullivan W. , Steeds John W. , von Bardeleben Hans Jürgen , Cantin J.L.
Published: March 2009

Several 4H SiC samples have been electron-irradiated at near threshold energies at low
fluence, either along the [0001] or [000-1] direction. PL and EPR techniques have been used to
investigate the dependence of the beam direction on defect generation and, together with a sample
irradiated at a higher fluence, to correlate differences brought about by irradiating with a change in
electron fluence. Attempts are made to correlate the information derived from the two techniques.
Deep Level Defects Related to Carbon Displacements in n- and p-Type 4H-SiC
Authors: Storasta L. , Kamata Isaho , Nakamura Tomonori , Tsuchida Hidekazu
Published: March 2009

We have investigated the electrically active deep level defects in p- and n-type 4H-SiC after
low energy electron irradiation. Intrinsic defects were created by irradiation with 200 keV electrons,
with energy sufficient to move only the carbon atoms in SiC lattice. Defect spectra were compared
between the p- and n-doped samples prepared under identical irradiation conditions. We probed both
conduction and valence band sides of the band-gap by using capacitance transient techniques with
electrical and optical trap filling. We have found that the defect spectrum in the p-type epilayers
differs significantly from the n-type. The Z1/Z2, EH1 and EH3 electron traps which are usually present
in irradiated n-type material could not be detected in p-type samples. An electron trap at 1.6 eV below
the conduction band edge is present in both n- and p-type samples at the same energy position and
with similar concentration, therefore it is probably related to the same type of defect. We have also
found a new hole trap in p-type epilayers at energy EV + 0.66 eV.
Deep Level Point Defects in Semi-Insulating SiC
Authors: Zvanut Mary Ellen , Lee Won Woo , Wang Hai Yan , Mitchel W.C. , Mitchell William D.
Published: March 2009

The high resistivity of SiC required for many device applications is achieved by
compensating residual donors or acceptors with vanadium or intrinsic defects. This work addresses the
defect levels of substitutional vanadium and the positively charged carbon vacancy (VC
+) in semiinsulating
(SI) SiC. After reviewing the earlier studies related to both defects, the paper focuses on
temperature-dependent Hall measurements and photo-induced electron paramagnetic resonance (EPR)
experiments of 4H and 6H SI SiC. In vanadium-doped samples, a V3+/4+ level near Ec-1.1 eV (4H) and
Ec-0.85 eV (6H) is estimated by a comparison of dark EPR spectra and the activation energy
determined from the Hall data, assuming that vanadium controls the Fermi level. In high purity semiinsulating
substrates, analysis of time-dependent and steady-state photo-EPR data suggests that the
plus-to-neutral transition of the carbon vacancy involves a structural relaxation of about 0.6 eV.
Signature of the Negative Carbon Vacancy-Antisite Complex
Authors: Bockstedte M. , Gali Adam , Umeda T. , Son Nguyen Tien , Isoya Junichi , Janzén Erik
Published: March 2009

The negative carbon vacancy antisite complex is analysed by ab initio theory in view of the
SI5 EPR-center. The complex occurs in a Jahn-Teller distorted ground state and a meta stable state.
This and the calculated hyperfine structure agree nicely with the temperature dependent EPR spectra
of SI5. An interpretation of the photo-EPR experiments is proposed.
Identification of the Triplet State N-V Defect in Neutron Irradiated Silicon Carbide by Electron Paramagnetic Resonance
Authors: Muzafarova Marina V. , Ilyin Ivan V. , Mokhov E.N. , Sankin Vladimir Ilich , Baranov P.G.
Published: March 2009

Two types of a new triplet centers labeled as N-V have been observed in heavily neutron
irradiated (dose of 1021 cm-2) and high-temperature annealed (2000°C) 6H-SiC crystals. The centers
have an axial symmetry along c-axis. Anisotropic hyperfine splitting due to the one 14N nucleus has
been observed. The EPR spectra of N-V defects in the triplet state in 6H-SiC reveal strong
temperature dependence. The parameters of these centers are similar to that for well-known N-V
center in diamond. It seems to consist of silicon vacancy and carbon substitutional nitrogen in the
adjacent lattice cites oriented along c-axis. Similar to the diamond N-V centers in SiC have been
produced by neutron irradiation and high-temperature annealing of the crystals containing nitrogen.
For the first shell the structure of the N-V defect in 6H-SiC is practically identical with that in
diamond. The charge state of this defect seems to be +1 compare with neutral state for nitrogensilicon
vacancy defect in 6H-SiC with S=1/2.
Clustering of Vacancies in Semi-Insulating SiC Observed with Positron Spectroscopy
Authors: Aavikko Reino , Saarinen Kimmo , Magnusson Björn , Janzén Erik
Published: March 2009

Positron annihilation radiation Doppler broadening spectroscopy was used to study defects
in semi-insulating (SI) silicon carbide (SiC) substrates grown by high-temperature chemical vapour
deposition (HTCVD). The Doppler broadening measurements show (i) that the measured samples
contain vacancy clusters (ii) that the positron trapping to the clusters is increased in annealing (iii)
that the chemical environment of the defects in the un-annealed samples is different from those of the
annealed samples.
Photoluminescence of Phosphorous Doped SiC
Authors: Henry Anne , Janzén Erik
Published: March 2009

We report the results of a photoluminescence (PL) study of n-type phosphorus-doped SiC
epilayers. The PL spectra consist of a set of sharp lines that are interpreted as excitons bound to the
P donor with zero-phonon lines which have photon energies very close to the nitrogen-bound
excitons and followed by phonon assisted replicas.
Kinetic Mechanisms for the Deactivation of Nitrogen in SiC
Authors: Bockstedte M. , Mattausch Alexander , Pankratov Oleg
Published: March 2009

Kinetic mechanisms for the deactivation of nitrogen are investigated by ab initio
theory. We find that the interaction of nitrogen with self-interstitials can lead to a deactivation
of nitrogen, yet it cannot explain the experimentally observed nitrogen deactivation at high
temperatures in silicon co-implanted samples. Our analysis suggests the aggregation of vacancies
at high temperatures and the subsequent formation of passive nitrogen-vacancy complexes as
a likely explanation.
Europium Induced Deep Levels in Hexagonal Silicon Carbide
Authors: Pasold G. , Albrecht F. , Hülsen C. , Sielemann R. , Witthuhn W.
Published: March 2009

Silicon carbide (SiC) was investigated for deep band gap states of europium
by means of deep level transient spectroscopy (DLTS). The knowledge of the properties of
optoelectrically active impurities or defects is essential for a detailed understanding of the
energy-transfer process resulting in the observable excitations [1].
SiC-samples of the polytypes 4H as well as 6H are ion-implanted by different europium-
isotopes in order to obtain a chemical identification of the characterized energy levels. Here
the concentration sensitivity of the DLTS is applied to observe the elemental transmutation
of the incorporated radioactive tracer atoms 146Eu (t1/2=4.51 d) and 147Eu (t1/2=24.6 d).
DLTS on samples implanted with stable Eu-ions (153Eu) was carried out for comparison
and manifestation of the results. From these studies 5 Eu-related deep band gap levels are
established: in 4H-SiC two levels at EV+0.86(2) eV and EC−0.47(2) eV, and in 6H-SiC three
levels at EV+0.88(2) eV, EC−0.29(2) eV and EC−0.67(2) eV.
A Comparison of Various Surface Finishes and the Effects on the Early Stages of Pore Formation during High Field Etching of SiC
Authors: Ke Yue , Moisson Catherine , Gaan S. , Feenstra R.M. , Devaty Robert P. , Choyke Wolfgang J.
Published: March 2009

The effects of initial surface morphology on the early stages of porous SiC formation
under highly biased photoelectrochemical etching conditions are discussed. We etched both Si-face
and C-face polished n-type 6H SiC with different surface finishes prepared either by mechanical
polishing or by chemical mechanical polishing at NOVASiC. For both Si-face and C-face porous
SiC samples, a variety of surface and cross sectional porous morphologies, due to different surface
finishes, are observed. The proposed explanation is based on the spatial distribution of holes at the
interface of the SiC and electrolyte inside the semiconductor.
Formation, Morphology and Optical Properties of SiC Nanopowder
Authors: Nychyporuk Tetyana , Marty Olivier , Bluet Jean Marie , Lysenko Vladimir , Perrin Robert , Guillot Gérard , Barbier Daniel
Published: March 2009

SiC nanopowder has been formed using an original technological approach based on
grinding of bulk porous SiC nanostructures. The initial porous SiC nanostructures were obtained by
anodization of n+-type 4H-SiC substrate in HF/Ethanol solution under UV illumination. Large
single SiC nanoparticles (~ 30 nm in diameter) constituting the nanopowder have a porous structure
which can be clearly visible. On the other hand, small single SiC nanoparticles (~ 4 nm in diameter)
exhibit a clear crystalline structure. A broad and very intense luminescence band (400 – 900 nm)
provided from the nanopowder corresponds to the radiative processes involving nanoparticle
surface states. A smaller photoluminescence peak centred at 358 nm may correspond to radiative
recombination of the photogenerated excitons confined in the individual and spatially separated 4HSiC
nanoparticles.
Variations in the Effects of Implanting Al at Different Concentrations into SiC
Authors: Jones Kenneth A. , Zheleva T.S. , Shah Pankaj B. , Derenge Michael A. , Freitas Jaime A. , Gerardi G.J. , Vispute R.D. , Hullavarad Shiva S. , Dar S.
Published: March 2009

SiC samples implanted at 600°C with 1018, 1019, or 1020 cm-3 of Al to a depth of ~ 0.3
μm and annealed with a (BN)AlN cap at temperatures ranging from 1300 – 1700°C were studied.
Some of the samples have been co-implanted with C or Si. They are examined using Hall, sheet
resistivity, CL, EPR, RBS, and TEM measurements. In all instances the sheet resistance is larger
than a comparably doped epitaxial layer, with the difference being larger for samples doped to
higher levels. The results suggest that not all of the damage can be annealed out, as stable defects
appear to form, and a greater number or more complex defects form at the higher concentrations.
Further, the defects affect the properties of the Al as no EPR peak is detected for implanted Al, and
the implanted Al reduces the AlSi peak intensity in bulk SiC. CL measurements show that there is a
peak near 2.9941 eV that disappears only at the highest annealing temperature suggesting it is
associated with a complex defect. The DI peaks persist at all annealing temperatures, and are
possibly associated with a Si terminated partial dislocation. TEM analyses indicate that the defects
are stacking faults and/or dislocations, and that these faulted regions can grow during annealing.
This is confirmed by RBS measurements.
Hydrogen-Induced Blistering of SiC: The Role of Post-Implant Multi-Step Annealing Sequences
Authors: Malouf G. , Poust B. , Hayashi S. , Yoshizawa G. , Goorsky M.S.
Published: March 2009

Hydrogen-exfoliation has become a viable approach to transfer SiC thin layers onto
different substrate materials. However, little attention has been paid to the exfoliation-inducing
annealing conditions. To investigate the annealing conditions, 4H SiC wafers were implanted with
either 2.5×1016 H2
+ cm-2 or 5.0×1016 cm-2at 37 KeV. Post-implant, multi-step annealing sequences
were examined in order to promote more efficient blistering, and it was found that a low
temperature initial annealing step (T ≈ 500°C) can decrease the annealing time necessary in the
high temperature regime; this was attributed to a nucleation of hydrogen induced platelet defects
during the low temperature annealing regime and efficient splitting during a higher temperature
(900 °C) anneal. This process is similar to what is observed for InP and Si exfoliation, except that
the annealing processes occur at higher temperature.
Structural Properties of Titanium-Nickel Films on Silicon Carbide Following High Temperature Annealing
Authors: Vassilevski Konstantin , Nikitina Irina P. , Horsfall Alton B. , Wright Nicolas G. , Johnson C. Mark , Malhan Rajesh Kumar , Yamamoto Tetsuya
Published: March 2009

Structural properties of Ni/Ti films deposited on 4H-SiC and annealed at temperatures
from 800 to 1040°C have been studied. Films with three different metal deposition sequences were
investigated by X-ray diffraction and Auger electron spectroscopy: (A) Ti(100 nm)/Ni(50 nm); (B)
Ti(4 nm)/Ni(50 nm)/Ti(100 nm); and (C) Ti(4 nm)/Ni(150 nm). A distinct spatial separation of
nickel silicide and titanium carbide layers was observed in all samples. It was discovered that the
distribution of the products of the solid state chemical reaction in samples (A) and (B) was
independent on the deposition sequence of Ti and Ni layers. The titanium carbide layer located on
the interface and covered by the clearly separated nickel silicide layer was detected in both samples
after heat treatments.
Composite Ohmic Contacts to SiC
Authors: Adedeji A.V. , Ahyi Ayayi Claude , Williams John R. , Bozack M.J. , Mohney S.E. , Liu B. , Scofield James D.
Published: March 2009

Composite ohmic contacts designed for SiC devices operating in air at 350°C have
been studied. Ohmic contacts to n- and p-4H-SiC were protected against inter-diffusion and
oxidation by Ta-Si-N layers obtained by sputter deposition from a TaSi2 target in a mixture of
Ar and N2. Platinum was sputter-deposited at 250°C to promote adhesion between the Ta-Si-
N barrier layer and a thick Au cap layer. Platinum also acts as a barrier to the diffusion of
Au. The electrical and mechanical characteristics of the composite contacts were stable after
hundreds of hours of annealing in air at 350°C. We report the effects of thermal aging on the
specific contact resistance and the semiconductor sheet resistance, and the results of wire
bond pull and shear tests following aging for Ta-Si-N / Pt / Au stacks deposited on both SiO2
dielectric layers and the ohmic contact layers.