bluuebunny/crossref_metadata_2025 huggingface dataset:
The Influence of Radiation Defects on the Charge Transport in SiC Nuclear Detectors in Conditions of Elevated Temperatures and Deep Compensation of the Conductivity
Authors: Ivanov Alexander M. , Strokan Nikita B. , Lebedev Alexander A. , Kozlovski Vitalii V.
Published: March 2009

P+–n–n+-detector structures based on CVD films with an uncompensated donor
concentration of 2×1014 cm-3 have been studied. The p+-region was created by implantation of Al
ions. Preliminarily, the detectors were irradiated with 8 MeV protons at a fluence of 3×1014 cm-2
and then annealed in a vacuum at 600°C for 1 h and 700°C for 1 h. Nuclear spectrometric
techniques with 5.4 MeV a-particles were employed to test the detectors. In measurements
performed in the temperature range 20–150°C, the forward- and reverse-bias modes were
compared. It is shown that the annealing leads to a higher collection efficiency of carriers generated
by nuclear radiation and to a decrease in the amount of charge accumulated by traps in the course of
testing. Despite the positive effect of the annealing, there remains a considerable amount of
radiation defects, which is manifested, in particular, in the kinetics of the forward current.
High Power-Density SiC Converter
Authors: Kinouchi Shin Ichi , Nakatake Hiroshi , Kitamura T. , Azuma S. , Tominaga S. , Nakata Shuhei , Nakao Yukiyasu , Oi T. , Oomori Tatsuo
Published: March 2009

A compact SiC converter having power densities about 9 W/cm3 is designed and
fabricated. It is confirmed that the converter operates in a thermally permissive range. The power
loss of the module of the converter measured under motor operations is less than 50% of the
similar-rating Si module loss. The shrink of the effective volume of DC-link capacitor is necessary
to achieve the high power-density SiC converter, in addition to the decrease of the cooling system
volume due to the loss reduction caused by SiC devices.
A High Performance CCM PFC Circuit Using a SiC Schottky Diode and a Si SuperFETTM Switch
Authors: Choi Won Suk , Young Sung Mo , Woodin Richard L. , Witt A.W. , Shovlin J.
Published: March 2009

SuperFETTM MOSFETs and silicon carbide (SiC) Schottky diodes are applied to
continuous conduction mode active power factor correction pre-regulators. SuperFETTM MOSFETs
can reduce power losses dramatically with their extremely low RDS(ON) and fast switching. The SiC
Schottky diode has virtually zero reverse recovery current and high thermal conductivity, and is close
to an ideal diode for a CCM PFC circuit. Due to these outstanding switching characteristics,
frequency can be increased. In this paper, the SiC Schottky diode’s and SuperFETTM MOSFET’s
performance have been verified in a CCM PFC boost converter. These products can reduce the total
power losses and enhance the system efficiency.
Growth of Thick AlN Layers by High Temperature CVD (HTCVD)
Authors: Claudel Arnaud , Blanquet Elisabeth , Chaussende Didier , Audier M. , Pique D. , Pons Michel
Published: March 2009

To achieve AlN bulk growth, HTCVD chlorinated process is investigated. High growth
rate and high crystalline quality are targeted for AlN films grown on (0001) α-Al2O3 and (0001) 4H
or 6H SiC substrates between 1100 °C and 1750 °C. The precursors used are ammonia NH3 and
aluminium chlorides AlClx species formed in situ by action of Cl2 on high purity Al wire. Both
influences of temperature and carrier gas on microstructure, crystalline state and growth rate are
presented. Growth rates higher than 190 μm.h-1 have been reached. Thermodynamic calculations
were carried out to understand the chemistry of AlN deposition. AlN layers were characterized by
SEM and θ/2θ X-Ray Diffraction. Their epitaxial relationships with substrates were deduced from
pole figures obtained by X-Ray diffraction on a texture goniometer.
Epitaxial Lateral Overgrowth of (1-100) m-Plane GaN on m-Plane 6H-SiC by Metalorganic Chemical Vapor Deposition
Authors: Ni X. , Özgür Ü. , Chevtchenko S. , Nie J. , Morkoç Hadis , Devaty Robert P. , Choyke Wolfgang J.
Published: March 2009

Planar m-plane GaN was grown on (1100) m-plane 6H-SiC substrates using
high-temperature AlN nucleation layers by metalorganic chemical vapor deposition. Scanning
electron microscopy (SEM) and atomic force microscopy (AFM) images showed striated features on
the sample surface aligned along the GaN [1120] direction, which are perpendicular to those
associated with (1120) a-plane GaN. The epitaxial relationship between the m-GaN and 6H-SiC was
analyzed using high-resolution x-ray diffraction (XRD). In order to reduce the defect density,
epitaxial lateral overgrowth (ELO) was carried out on an m-GaN template with mask stripes along the
GaN [1120] direction, which makes the lateral growth fronts advance along the GaN c-axis. On-axis
XRD rocking curves show that the full width at half maximum (FWHM) values for the ELO samples
were reduced by nearly half when compared to those of the m-plane template without ELO. Clear
atomic steps were observed in the wing regions by AFM. The absence of the striated features that are
associated with the template could be indicative of the reduction of basal stacking faults in the ELO
wings. Low-temperature photoluminescence (PL) spectra showed an excitonic emission at 3.47eV, a
basal stacking fault (BSF)-related emission at 3.41 eV, and other defect-related emissions at 3.29 eV
and 3.34 eV.
Surface Morphology of AlN Epitaxial Layer Grown on Various SiC Substrates by Sublimation Closed Space Technique
Authors: Lee Gi Sub , Kyun Myung Ok , Hwang Hyun Hee , An Joon Ho , Lee Won Jae , Shin Byoung Chul , Nishino Shigehiro
Published: March 2009

A sublimation epitaxial method, referred to as the Closed Space Technique (CST) was
adopted to produce AlN epitaxial layers. In this study, we report the surface morphology of AlN
epitaxial layer grown on various substrates such as 3C-SiC (100), 4H-SiC (0001) with 8o off-axis
(0001) plane tilted toward the <11 2 0> direction and on-axis 4H-SiC (0001). An average growth rate
of AlN layer at 2350oC in 500 Torr of N2 was measured to be about 6μm/hr. While AlN layer grown
on the 3C-SiC (100) substrate at 2350oC exhibited polycrystalline structure, AlN epitaxial layer
grown on on-axis and off-axis 4H-SiC (0001) substrates had highly c-axis oriented epitaxial structure.
In particular, the stacked structure of hexagonal plates was observed on off-axis substrate and the size
of the hexagonal plates increased with growth time. Hexagonal plates were observed to be coalesced
and the step-bunching was finally disappeared.
Raman Scattering Analysis of Electrical Property and Crystallinity in Freestanding GaN Crystals with Various Impurity Concentrations
Authors: Kitamura T. , Nakashima Shinichi , Okumura Hajime
Published: March 2009

We characterized the HVPE grown freestanding GaN crystals with various shallow impurity
concentrations by Raman scattering spectroscopy. Electrical properties such as free carrier
density were examined for the GaN crystals through Raman measurements of the A1 LO-phonon
plasmon coupled (LOPC) mode and its line shape analysis. The asymmetric broadening and the
up-shift of the LOPC band were clearly observed as the carrier density increased from 1017 to 1019
cm-3. The line shape analysis revealed that the carrier density in the GaN crystals can be simply estimated
from measured frequency shift of LOPC mode. The variations of the width for TO phonon
bands were also observed in this carrier density range. The band widths were slightly increased by 0.2
cm-1 as the impurity concentration increased from 1018 to 1019 cm-3 in samples with low dislocation
density.
DC and RF Performance of Diamond MISFETs with Alumina Gate Insulator
Authors: Hirama Kazuyuki , Jingu Yoshikatsu , Ichikawa Masaru , Umezawa Hitoshi , Kawarada Hiroshi
Published: March 2009

We fabricated diamond MISFETs on polycrystalline films using alumina gate insulator. A
hole accumulation layer has been utilized as hole current channel. The hydrogen-termination was
achieved by remote hydrogen plasma. The sheet resistance strongly depends on the substrate
temperature during hydrogen-termination process. The polycrystalline diamond MISFETs showed
high drain current density of -650 mA/mm and cut-off frequency of 42 GHz. These values are higher
than those of single crystal diamond FETs ever reported.
Theoretical Monte Carlo Study of the Formation and Evolution of Defects in the Homoepitaxial Growth of SiC
Authors: Camarda Massimo , La Magna Antonino , Fiorenza Patrick , Izzo Gaetano , La Via Francesco
Published: March 2009

A novel Monte Carlo kinetic model has been developed and implemented to predict growth rate regimes and defect formation for the homo-epitaxial growth of various SiC polytypes on different substrates. Using this model we have studied the generation of both point like and extended defects in terms of the growth rate and off-cut angle, finding qualitative agreement with both electrical and optical characterization and analytical results.
Annealing Behavior of Defects in Multiple-Energy Nitrogen Implanted ZnO Bulk Single Crystal
Authors: Kuriyama K. , Matsumoto K. , Ooi M. , Kushida K.
Published: March 2009

Multiple-energy nitrogen ions (energies:1 to 100 keV and a net concentration:2.24 x 1020
cm-3) are implanted into ZnO bulk single crystals grown by the hydrothermal method. Rutherford
backscattering-channeling studies show the presence of displaced Zn atoms (Zni) of about 4 % in
as-implanted samples. An A-emission band related to the interstitial oxygen (Oi) is observed at 580
nm in 600 oC-annealed samples, and a new emission appears at 515 nm in 800 oC-annealed samples.
It is proposed that the new emission band consists of the superposition of the green band (~525 nm)
observed in unimplanted ZnO and the residual A-emission band. In 800 oC-annealed samples, a
band to acceptor transition at 3.26 eV is also observed in addition to a donor to acceptor pair
transition, suggesting that nitrogen acceptor is located at about 180 meV above the valence band. A
thermally stimulated current peak, P1 (165 meV), which has been attributed to a native point defect,
observed in unimplanted samples almost disappears in nitrogen-implanted samples annealed at 800
oC.
Growth of 6H-SiC Single Crystals under Quasi-Equilibrium Conditions
Authors: Tymicki Emil , Grasza Krzysztof , Hofman Władysław , Diduszko Ryszard , Bożek Rafał
Published: March 2009

Silicon carbide single crystals grown by the seeded physical vapour transport method have been investigated. These crystals were grown on the Si-face (0001) of 6H-SiC seeds. The growth proceeded under quasi-equilibrium conditions with the growth rate in the range 0.05-0.2 mm/h, that was extremely low as compared to used in standard growth processes. The shape and morphology of the crystallization fronts have been studied. Moreover, defects in crystals and wafers cut from these crystals were examined by optical and atomic force microscopy combined with KOH etching and X-Ray diffraction.
Effect of Substrates Thermal Etching on CVD Growth of Epitaxial Silicon Carbide Layers
Authors: Strupiński Wlodek , Kościewicz Kinga , Weyher Jan , Olszyna Andrzej Roman
Published: March 2009

The influence of in situ etching of Si-face n-4H-SiC wafers in H2 and propane on the surface morphology of the grown epi-layers were examined using differential interference contrast (DIC) optical microscopy and atomic force microscope (AFM). Two defect-selective etching techniques were applied in order to reveal the type and spatial distribution of defects in the substrates and epi-layers. It was found that for the flow applied in this experiment propane plays a significant role for the etching process. Depending on temperature and etching time we obtained completely different picture of substrate surface morphology. The propane etching was verified as a tool for substrate surface improvement.
Local-Loading Effect in Low-Temperature Selective Epitaxial Growth of 4H-SiC by Halo-Carbon Method
Authors: Das Hrishikesh , Krishnan Bharat , Melnychuk Galyna , Koshka Yaroslav
Published: March 2009

In this work, the local-loading effect and its influence on the growth rate enhancement and the growth rate non-homogeneity is investigated during the halo-carbon low-temperature selective epitaxial growth (LTSEG) using an SiO2 mask. The average growth rate during the LTSEG can be more than three-times higher than in blanket epitaxy at the same growth conditions. Both the size of the LTSEG seed windows and the surrounding area covered with the mask determine the growth rate non-homogeneity. A model for predicting the growth rate distribution is suggested.
In Situ Nitrogen and Aluminum Doping in Migration Enhanced Embedded Epitaxial Growth of 4H-SiC
Authors: Schöner Adolf , Sugiyama Naohiro , Takeuchi Yuuichi , Malhan Rajesh Kumar
Published: March 2009

The in-situ doping of aluminum and nitrogen in migration enhanced embedded epitaxy (ME3) is investigated with the aim to apply it to the realization and fabrication of all-epitaxial, normally-off 4H-SiC JFET devices. This ME3 process consists of the epitaxial growth of an n-doped channel and a highly p-doped top gate in narrow trenches. We found that the nitrogen doping in the n-channel (a-face) is a factor 1.5 higher than layers grown with the same process on Si-face wafers. Due to the low C/Si ratio and the low silane flow rate used in the ME3 process, the growth of the p-doped top gate needs high flow rates of the aluminum precursor trimethylaluminum for several hours, which contaminates the CVD reactor and causes aluminum memory effects. These aluminum memory effects can be reduced by an extra high temperature bake-out run.
Epitaxial TaC Films for the Selective Area Growth of SiC
Authors: Jones Kenneth A. , Zheleva T.S. , Vispute R.D. , Hullavarad Shiva S. , Ervin M. , Dhar S.
Published: March 2009

At sufficiently high temperatures PLD deposited TaC films can be grown epitaxially on 4H-SiC (0001) substrates; at lower temperatures the films recrystallize and ball up forming a large number of pinholes. The growth temperature for epitaxy was found to be 1000°C, and it was facilitated by the epitaxial growth of a thin (2 nm) transition layer of hexagonal Ta2C. High temperature annealing produced changes in the surface morphology, caused grain growth, and created pin holes through a recrystallization process in the films deposited at the lower temperatures, while the films deposited at the higher temperatures remained virtually unchanged. Using TEM it is shown that the (0001) basal planes of the hexagonal 4H-SiC and Ta2C phases are aligned, and they were also parallel to the (111) plane in the cubic TaC with the [101] cubic direction being parallel to the hexagonal [2110] hexagonal direction. The Ta2C interlayer most likely is formed because its lattice parameter in the basel plane (3.103 Ǻ) is intermediate between that of the 4H-SiC (3.08 Ǻ) and the TaC (3.150 Ǻ). Given that Al.5Ga.5N is lattice matched to TaC, it could be an excellent substrate for the growth of GaN/AlGaN heterostructures.
Aluminum P-Type Doping of Bulk SiC Single Crystals by Tri-Methyl-Aluminum
Authors: Hens Philip , Künecke Ulrike , Wellmann Peter J.
Published: March 2009

We present p-type doping of bulk SiC crystals by the modified physical vapor transport (M-PVT) technique using TMA (Tri-Methyl-Aluminum). Using TMA as a dopant precursor allows a quite well defined crystal growth process control. The issue of improvement of conductivity (reduction of substrate resistivity) by reduction of unintentional acceptor compensation by nitrogen is addressed. It is shown that a decrease of compensation from approx. 3%...10% to approx. 0.5%...2.5% leads to a charge carrier mobility and, hence, conductivity increase of about factor two.
Solution Growth of 3C-SiC Single Crystals by Cold Crucible Technique
Authors: Tanaka Takashi , Yashiro Nobuyoshi , Kusunoki Kazuhiko , Kamei Kazuhito , Yauchi Akihiro
Published: March 2009

We have successfully grown 3C-SiC(111) single crystals 10mm x 10mm in dimension on 6H-SiC(0001) substrate by the solution growth method using cold crucible technique. The growth rate of 60μm/hr was achieved. The use of Si-Ti-C ternary solution as well as the electromagnetic stirring are responsible for the relatively high growth rate in solution method. The threading dislocation density is low and the etch pit density amounts to 105-106 /cm2 at the lowest region. Polytype of the grown layer has changed from 3C to 6H with an increase in the dip depth of substrate. A mathematical model was applied to get better understanding of what happened in the crucible.
3C-SiC Islands Formation on 6H-SiC(0001) Substrate from a Liquid Phase
Authors: Kim-Hak Olivier , Soueidan Maher , Ferro Gabriel , Dezellus Olivier , Andreadou Ariadne , Carole Davy , Polychroniadis Efstathios K. , Viala Jean Claude
Published: March 2009

Twin-free 3C-SiC layers were recently obtained by Vapour-Liquid-Solid mechanism on a a-SiC(0001) substrate using Si-Ge melt. The formation of cubic layers is rather unexpected since growth from the melt is known to promote lateral growth and should thus give homoepitaxial layers. The study of the early stage of such growth, after a simple contact between the melt and the substrate (without adding propane), reveals the precipitation of 3C-SiC elongated islands upon the substrate surface. The chemical interactions inside the Ge-Si-C ternary phase diagram suggest an initial dissolution of the SiC seed in contact with a Ge-rich melt (below 1200°C). When the Si content of the melt subsequently increases upon heating, the dissolved carbon atoms precipitate on the seed surface under the form of 3C-SiC islands. When propane is added, these islands enlarge and coalesce to form a complete 3C layer.
Structural and Morphological Characterization of 3C-SiC Films Grown on (111), (211) and (100) Silicon Substrates
Authors: Portail Marc , Nemoz M. , Zielinski Marcin , Chassagne Thierry
Published: March 2009

The structural and morphological modifications induced by the carbonization stage upon 3C-SiC heteroepitaxial films grown on (111) and (100) oriented silicon substrates have been investigated. The crystalline quality of the films is strongly dependent on the carbonization parameters (propane flow rate and duration of carbonization). The (111) heteroepitaxial films coalesce more rapidly and present a lower dependence on the carbonization conditions than (100) films. By comparing the evolution of the interfacial defects (voids) density with existing models, we show that this is related to the initial mechanisms occurring during the carbonization stage. The twin defects densities on (111), (100) and (211) films are also investigated and the role of the only carbonization stage on their formation is studied.
Buckling Stabilization and Stress Reduction in SiC on Si by i-FLASiC Processing
Authors: Andreadou Ariadne , Pezoldt Joerg , Förster Christian , Polychroniadis Efstathios K. , Voelskow M. , Skorupa Wolfgang
Published: March 2009

One of the main challenging tasks in the prospective technology is the buckling suppression of the 3C-SiC film due to the melting and solidification process and the stress relief as a consequence of the short time Si melting during the Flash Lamp Annealing. To overcome this effect and to stabilize a flat surface morphology an alternative i-FlASiC process was developed. This work refers to the influence of the layer stack modifications by doping and meltstop formation by ion implantation on the wafer buckling. The samples were studied by transmission electron microscopy, high resolution x-ray diffraction and infrared ellipsometry. The aim was to optimize the doping and flash lamp annealing conditions in relation to the i-FLASiC layer stack modification.
Hetero-Epitaxial Growth of 3C-SiC with Smooth Surface on Si(001) Using Acetylene Gas
Authors: Hirabayashi Yasuo , Kaneko Satoru , Akiyama Kensuke
Published: March 2009

The carbonization conditions (acetylene pressure and heating rate) to obtain close carbonized layer covered on Si(001) substrate without thermal pits is studied. Subsequent hetero-epitaxial 3C-SiC with smooth surface have been grown by low-pressure CVD. Single-crystalline carbonized layers could be grown at 1050°C by using suitable carbonization processes. The surfaces of Si were covered with single-crystalline 3C-SiC layers at an early stage of carbonization, preventing out-diffusion of Si atoms from Si substrates. 3C-SiC epi-film have RMS = 0.4nm but no single domain. The protrusion density of the film was an order of 1000 cm-2.
Characteristics of Polycrystalline 3C-SiC Thin Films Grown on AlN Buffer Layer by CVD
Authors: Chung Gwiy Sang , Kim Kang San
Published: March 2009

This paper describes the characteristics of poly (Polycrystalline) 3C-SiC grown on SiO2 and AlN buffers, respectively. The crystallinity and the bonding structure of poly 3C-SiC grown on each buffer layer were investigated according to various growth temperatures. The crystalline quality of poly 3C-SiC was improved from resulting in decrease of FWHM (Full width half maximum) of XRD and FT-IR by increasing the growth temperature. The minimum growth temperature of poly 3C-SiC was 1100 °C. The surface chemical composition and the electron mobility of poly 3C-SiC grown on each buffer layer were investigated by XPS and Hall Effect. The chemical compositions of surface of poly 3C-SiC grown on SiO2 and AlN were not different. However, their electron mobilities were 7.65 ㎝2/V.s and 14.8 ㎝2/V.s, respectively. Therefore, since the electron mobility of 3C-SiC/AlN was two times higher than that of 3C-SiC/SiO2, AlN is a suitable material, as buffer layer, for SiC growth with excellent crystalline quality.
Investigation of Defect Formation in 4H-SiC(0001) and (000-1) Epitaxy
Authors: Tsuchida Hidekazu , Kamata Isaho , Nagano Masahiro
Published: March 2009

Defect formation in 4H-SiC(0001) and (000-1) epitaxy is investigated by grazing
incidence synchrotron reflection X-ray topography and transmission electron microscopy. Frank-type
faults, which are terminated by four Frank partials with a 1/4[0001] type Burgers vector with the same
sign on four different basal planes, are confirmed to be formed by conversion of a 1c threading edge
dislocation (TSD) in the substrate as well as simultaneous generation of a 1c TSD during epitaxy. The
collation between the topography appearance and the microscopic structure and the variety of Frank
faults are shown. Formation of carrot defects and threading dislocation clusters are also investigated.
Temperature Dependence of Shockley Stacking Fault Expansion and Contraction in 4H-SiC p-i-n Diodes
Authors: Caldwell Joshua D. , Stahlbush Robert E. , Glembocki Orest J. , Hobart Karl D. , Liu Kendrick X. , Tadjer Marko J.
Published: March 2009

The nucleation and expansion of Shockley stacking faults (SSFs) in 4H-SiC is known to
induce an increase in the forward voltage drop (Vf) of bipolar devices such as pin diodes. However,
recent annealing experiments have shown that SSFs can not only expand, but that low temperature
annealing (210-7000C) induces a contraction of the SSFs that is coupled with a full and repeatable
recovery of the Vf drift. Here we report that following extended periods of forward bias operation that
the Vf drift of 10kV 4H-SiC pin diodes saturates, with the saturation Vf drift dropping with increasing
stressing temperature. Upon reaching saturation, increases in temperature during forward bias
operation at the same injection conditions also lead to a partial recovery of the Vf drift. Furthermore,
the magnitude of this current-induced recovery is dependent upon the injection current, as reductions
in the current cause a slower, but larger overall Vf drift recovery. All of these results clearly indicate
that the current driving force models for SSF expansion are either incomplete or incorrect and that
further efforts are required for a more complete understanding of SSF dynamics to be obtained.
EPR Identification of Defects and Impurities in SiC: To be Decisive
Authors: Isoya Junichi , Umeda T. , Mizuochi N. , Son Nguyen Tien , Janzén Erik , Ohshima Takeshi
Published: March 2009

In EPR (electron paramagnetic resonance) identification of point defects, hyperfine (HF)
interaction is decisive information not only for chemical identity but also for the local geometry and
the electronic state. In some intrinsic defects in SiC, the wave function of the unpaired electron
extends quite unevenly among major atoms comprising the defects. In such a case, the determination
of the number of equivalent atoms and the chemical identity (Si or C) of those atoms even with weak
HF splitting are useful to compare with HF parameters obtained theoretically. For vacancy-related
defects of relatively deep levels, the sum of the spin densities on the nearest-neighbor shell is found to
be 60-68%.
Defects Identified in SiC and Their Implications
Authors: Bockstedte M. , Marini A. , Gali Adam , Pankratov Oleg , Rubio A.
Published: March 2009

Defect signatures, such as deep level positions, hyperfine parameters, local vibrational
modes and optical transitions characterize a defect and enable the identification of defect centers. This
identification is a key to an understanding of complex phenomena like the defect kinetics. Albeit
density functional theory enabled the identification of several defects and their kinetic properties, a
new approach is needed to address the optical excitation of defect. Within a quasiparticle theory and
taking into account excitonic effects we analyze the excited states of VC
+.
High-Resolution Topography Analysis on Threading Edge Dislocations in 4H-SiC Epilayers
Authors: Kamata Isaho , Nagano Masahiro , Tsuchida Hidekazu , Chen Yi , Dudley Michael
Published: March 2009

Threading edge dislocations (TEDs) in a 4H-SiC epitaxial layer are investigated using
high-resolution synchrotron topography. Six types of TED image are confirmed to correspond to the
Burgers vector directions by a comparison of computer simulated images and observed topography
images in crystal boundaries. Using a mapping method, a wide spatial distribution of the six types
of TED is examined in a quarter section of a 2-inch wafer.
Pair-Generation of the Basal-Plane-Dislocation during Crystal Growth of SiC
Authors: Nishiguchi Taro , Furusho Tomoaki , Isshiki Toshiyuki , Nishio Koji , Shiomi Hiromu , Nishino Shigehiro
Published: March 2009

4H-SiC was grown on 4H-SiC (1100) substrates by sublimation boule growth, and
transmission electron microscopic investigation was carried out. Two basal-plane-dislocations in the
same basal plane (the BPD pair), whose dislocation line extend toward the [1100] growth direction,
were observed as aligned along [0001]. The density of the BPD pairs along [0001] was in the same
order with that of the stacking faults in the sample. A threading screw-dislocation was observed in
between aligned BPD pairs. It is proposed that the interaction between stacking faults and threading
screw-dislocations on the grown surface generates the BPD pairs. Since a high density of stacking
faults is inherent to the growth on the substrates perpendicular to (0001), keeping an atomically flat
grown surface is important to prevent the generation of the threading screw-dislocations, and thus to
suppress the generation of the BPD pairs in case of the growth on (1100) and/or (11 2 0) substrates.
Stacking Fault Formation in Highly Nitrogen-Doped 4H-SiC Substrates with Different Surface Preparation Conditions
Authors: Katsuno Masakazu , Nakabayashi Masashi , Fujimoto Tatsuo , Ohtani Noboru , Yashiro Hirokatsu , Tsuge Hiroshi , Aigo Takashi , Hoshino Taizo , Tatsumi Kohei
Published: March 2009

The stacking fault formation in highly nitrogen-doped n+ 4H-SiC single crystal substrates
during high temperature treatment has been investigated in terms of the surface preparation
conditions of substrates. Substrates with a relatively large surface roughness showed a resistivity
increase after annealing at 1100°C, which was confirmed to be caused by the formation and
expansion of double Shockley-type basal plane stacking faults in the substrates. The occurrence of
the stacking faults largely depended on the surface preparation conditions of the substrates, which
indicates that the primary nucleation sites of stacking faults exist in the near-surface regions of
substrates. In this regard, mechano-chemically polished (MCP) substrates with a minimum surface
roughness (< 0.3 nm) exhibited no resistivity increase and very few stacking faults after annealing
even when the nitrogen concentration of the substrates exceeded 1×1019 cm-3.
Expansion of Stacking Faults in 4H-SiC Epitaxial Layer under Laser Light Excitation during Room Temperature Photoluminescence Mapping
Authors: Hoshino Norihiro , Tajima Michio , Naitoh M. , Okuno Eiichi , Onda Shoichi
Published: March 2009

We investigated the expansion of single Shockley stacking faults (SSFs) in a 4H-SiC
epitaxial layer under high-intensity scanning laser beam during room temperature photoluminescence
mapping, which is similar to the degradation of bipolar pin diodes during forward current injection.
In an epitaxial layer on an 8 off-axis (0001) substrate, the SSF-related intensity patterns induced by
scanning high-intensity laser beam were classified into two types. The first one was a triangular
pattern and the second a pattern which expanded in accordance with the motion of the scanning laser
beam. The origins of the SSFs responsible for both patterns are presumably due to the preexisting
basal plane dislocations and the dislocation-loops on the basal plane in the epitaxial layer,
respectively. On the other hand, most of the SSF-expansion in on-axis (11 2 0) epitaxial layers were
similar to the second type in the (0001) epitaxial layer. We, therefore, suggest that the
dislocation-loops, which were located close to the surface, were dominant nucleation-sites of the
SSFs in the (11 2 0) epitaxial layers.
Status of Large Diameter SiC Single Crystals at II-VI
Authors: Gupta Avinash K. , Zwieback Ilya , Souzis Andrew E. , Yoganathan Murugesu , Anderson Thomas
Published: March 2009

II-VI is developing large-diameter SiC crystals to be used as lattice-matched, high thermal conductivity substrates for new generation GaN-based and SiC-based semiconductor devices. Large-diameter 6H SiC single crystals are grown at II-VI using our Advanced PVT sublimation growth process. Stable SI properties are achieved by compensation with vanadium, which results in high and spatially uniform resistivity, on the order of 1011 Ohm-cm. The quality of the presently grown 100 mm 6H SI substrates has been dramatically improved [1], and they are free of edge defects. Micropipe density in the 100 mm 6H SI substrates ranges from 2 to 8 cm-2 and dislocation density from 3·104 to 6·104 cm-2. X-ray rocking curves measured on as-sawn 100 mm 6H wafers showed edge-to-edge lattice curvature () between 0.1° and 0.3° and FWHM of the rocking curve between 50 and 100 arc-seconds
Synchrotron X-Ray Topographic Studies of Recombination Activated Shockley Partial Dislocations in 4H-Silicon Carbide Epitaxial Layers
Authors: Chen Yi , Huang Xian Rong , Zhang Ning , Dudley Michael , Caldwell Joshua D. , Liu Kendrick X. , Stahlbush Robert E.
Published: March 2009

Electron-hole recombination activated Shockley partial dislocations bounding expanding
stacking faults and their interactions with threading dislocations have been studied in 4H-SiC
epitaxial layers using synchrotron x-ray topography. The bounding partials appear as white stripes
or narrow dark lines in back-reflection X-ray topographs recorded using the basal plane reflections.
Such contrast variations are attributable to the defocusing/focusing of the diffracted X-rays due to
the edge component of the partial dislocations, which creates a convex/concave distortion of the
basal planes. Simulation results based on the ray-tracing principle confirm our argument. The sign
of the partial dislocations can be subsequently determined.
Characterization of Traps in Semi-Insulating 4H-SiC by Discharge Current Transient Spectroscopy
Authors: Takahashi Miyuki , Matsuura Hideharu
Published: March 2009

In order to characterize traps in semi-insulating 4H-SiC that is regarded as an attractive
semiconductor for X-ray detectors, we apply discharge current transient spectroscopy (DCTS) that
is a graphical peak analysis method based on the transient reverse current of a diode. We have
found at least three types of traps whose emission rates at 373 K are 4.9×10-3, 8.3×10-3 and 8.0×10-2
s-1. Since it is difficult to characterize traps in semi-insulating semiconductors by transient
capacitance methods, it is demonstrated that DCTS is a powerful method for determining the
densities and emission rates of traps in semi-insulating semiconductors.
Contact-Less Electrical Defect Characterization of Semi-Insulating 6H-SiC Bulk Material
Authors: Hahn S. , Beyer Franziska Christine , Gällström Andreas , Carlsson Patrick , Henry Anne , Magnusson Björn , Niklas J.R. , Janzén Erik
Published: March 2009

The novel technique microwave detected photo induced current transient spectroscopy
(MD-PICTS) was applied to semi-insulating 6H-SiC in order to investigate the properties of inherent
defect levels. Defect spectra can be obtained in the similar way to conventional PICTS and DLTS.
However, there is no need for contacting the samples, which allows for non-destructive and spatially
resolved electrical characterization. This work is focused on the investigation of semi-insulating
6H-SiC grown under different C/Si-ratios. In the corresponding MD-PICTS spectra several shallow
defect levels appear in the low temperature range. However the peak assignment needs further
investigation. Additionally different trap reemission dynamics are obtained for higher temperatures,
which are supposed to be due to different compensation effects.
Photo-EPR Study of Vacancy-Type Defects in Irradiated n-Type 4H-SiC
Authors: Umeda T. , Morishita Norio , Ohshima Takeshi , Itoh Hisayoshi , Isoya Junichi
Published: March 2009

We report photo-induced electron paramagnetic resonance (photo-EPR) data for irradiated
n-type 4H-SiC. Energy levels and associated photo-induced transitions are discussed for silicon
vacancy (VSi), carbon vacancy (VC), carbon antisite-vacancy pair (CSiVC), and divacancy (VSiVC).
Infrared PL Signatures of n-Type Bulk SiC Substrates with Nitrogen Impurity Concentration between 1016 and 1017 cm-3
Authors: Glaser E.R. , Garces N.Y. , Caldwell Joshua D. , Carlos W.E. , Zvanut Mary Ellen , Magnusson Björn , Hansen Darren M. , Chung Gil Yong , Loboda Mark J.
Published: March 2009

Low temperature infrared photoluminescence (PL) performed on a large set of bulk SiC
substrates has revealed distinct series of lines between 0.8 and 1.5 eV for samples with nitrogen
levels between ~ 1016 and 1017 cm-3. Semi-insulating and intentionally N-doped wafers grown by
PVT and HTCVD were investigated. Two groups of PL lines clustered near 1.0 and 1.35 eV,
respectively, were observed in n-type 4H-SiC. Not surprisingly, a multiplicity of features at slightly
different energy positions was found for this emission from the 6H- and 15R-SiC polytypes. Both
sets of lines were not observed for substrates with N doping concentrations greater than 3x1017cm-3.
Thus, it appears this IR emission can serve as optical “fingerprints” of bulk n-type substrate with
moderate levels of N impurities. Models for the possible origins of these lines will also be
discussed.
A Comparison of Transient Boron Diffusion in Silicon, Silicon Carbide and Diamond
Authors: Linnarsson Margareta K. , Isberg J. , Schöner Adolf , Hallén Anders
Published: March 2009

The boron diffusion in three kinds of group IV semiconductors: silicon, silicon carbide
and synthetic diamond has been studied by secondary ion mass spectrometry. Ion implantation of
300 keV, 11B-ions to a dose of 21014 cm-2 has been performed. The samples are subsequently
annealed at temperatures ranging from 800 to 1650 °C for 5 minutes up to 8 hours. In silicon and
silicon carbide, the boron diffusion is attributed to a transient process and the level of out-diffusion
is correlated to intrinsic carrier concentration. No transient, out-diffused, boron tail is revealed in
diamond at these temperatures.
Titanium Related Luminescence in SiC
Authors: Henry Anne , Bergman Peder , Janzén Erik
Published: March 2009

We report on the luminescence spectra related to Ti impurity in both 4H- and 6H-SiC
polytypes. The spectrum depends strongly on the polarization. They are two families of lines in 4H
and three in 6H. The main no-phonon line of each family is shown as a triplet and its phonon structure
contains both sharp and broad replicas. The higher energy family has also extra lines at high energy
appearing when the temperature increases. The spectra can be detected with excitation energy below
the excitonic bandgap and even with excitation energy below the spectrum itself. Time-resolved
photoluminescence reveals 0.1 ms long lifetime at low temperature.
Raman Investigation of the Effect of Metal Impurities at Gettering Sites on Phonon and Electron Related Properties of 4H-SiC n-n+ Junctions
Authors: Kazan Michel , Ottaviani Laurent , Masri Pierre M.
Published: March 2009

We report on the application of introducing gettering sites as an approach to control some
phonons and charge carrier related properties in 4H-SiC epilayer. Helium implantation (at room
temperature or 750°C) was first carried out, followed by a proper annealing and gold diffusion, in
order to check the gettering efficiency. Raman measurements showed the presence of the desired
defect, introduced by ion implantation at RT. The shift of the Fano interference allowed us to
calculate the free carriers’ density in each sample. The lowest value was found for the sample
implanted at RT. The gettering sites can act as majority carrier traps and reducers of recombination
processes, which can be interesting for devices designed for the detection of radiations.
Improvement of the Thermal Conductivity in 4H-SiC Epitaxial Layer by Introducing Gettering Sites
Authors: Ottaviani Laurent , Kazan Michel , Masri Pierre M. , Sauvage Thierry
Published: March 2009

Metal impurities are known to degrade dramatically the performances of silicon-based
devices, even at concentrations as low as 1012 cm-3. A specific process, named proximity gettering,
has been optimised by some authors in order to reduce the influence of these impurities [1]. This
process consists in the building of a favourable impurity trapping zone in a non-active area of the
device, by introducing implantation defects. This paper reports on the application of introducing
such gettering sites as an approach to control phonon properties in 4H-SiC epilayer, and increase
the thermal conductivity.
Optical Study of Ge Incorporation in Cubic SiC Layers Grown by VLS
Authors: Habka Nada , Soulière Véronique , Bluet Jean Marie , Soueidan Maher , Ferro Gabriel , Nsouli Bilal
Published: March 2009

We report an optical study of 3C-SiC layers grown on 6H-SiC substrates by VLS
mechanism using a Si-Ge melt. The photoluminescence and μ-Raman results show a clear and
significant incorporation of germanium in the layers from the melt. A photoluminescence emission
attributed to Ge related transitions is observed in the infrared region. μ-Raman spectra exhibit two
peaks related to the Ge-Ge and Si-Ge bonds. From the characteristics of these Raman peaks, it was
found that the amount of Ge incorporated inside the 3C layers increases with increasing Ge content
of the melt. This has been verified by Particle-Induced X-rays Emission (PIXE) measurements
which gave a Ge concentration varying from ~ 1x1019 to ~ 1x1020 at.cm-3. All these results suggest
that Ge incorporates in the VLS grown 3C layers by forming Si-Ge-(C) nanoclusters.
Galvanomagnetic Properties of 3C-SiC/6H-SiC Heterostructures
Authors: Lebedev Alexander A. , Abramov Pavel L. , Agrinskaya Nina V. , Kozub Ven I. , Kuznetsov Alexey N. , Lebedev Sergey P. , Oganesyan Gagik A. , Sorokin L.M. , Chernyaev A.V. , Shamshur Dmitrii
Published: March 2009

3C-SiC epitaxial layers were grown by method of sublimation epitaxy in vacuum on 6HSiC
substrates. It was done investigation of magneto resistance and Hall effect of 3C-SiC/6H-SiC
heterostructures in temperature range 1,4 – 300 К. At helium temperatures it was founded low
samples resistance and negative magneto-resistance in week magnetic field ( ~ 1 T). Analysis of
obtained results shows, that low samples resistance can be connected with metal-isolation junction
in 3C-SiC epitaxial films..
Rapid Characterization of SiC Crystals by Full-Wafer Photoluminescence Imaging under Below-Gap Excitation
Authors: Isono H. , Tajima Michio , Hoshino Norihiro , Sugimoto H.
Published: March 2009

We demonstrated the rapid and nondestructive observation of structural defects in SiC
wafers by full-wafer photoluminescence (PL) imaging under below-gap excitation. The use of
visible light emitting diode arrays as an excitation source is essential to the simplification of an
optical system and the light excitation covering the whole wafer. We were able to observe the
defect-related intensity patterns similar to those obtained by conventional laser-scanning PL mapping.
The measurement time of the PL imaging was more than fifty times faster than that of the PL
mapping.
Growth of 2H-SiC Single Crystals in a C-Li-Si Ternary Melt System
Authors: Imade Mamoru , Ogura Takashi , Uemura Masahiro , Kawamura Fumio , Yoshimura Masashi , Kitaoka Yasuo , Mori Yusuke , Sasaki Takatomo , Yamazaki Masanobu , Suwabe Shigekazu
Published: March 2009

We have achieved the first successful growth of 2H-SiC single crystals using the C-Li-Si melt system. Li-Si melt, whose melting point is lower than 1000 oC, was chosen because the 2H-SiC polytype is more stable at lower temperatures than other polytypes such as 3C-, 4H-, and 6H-SiC. Many hexagonal-shaped crystals of approximately 100 m in diameter were observed via a scanning electron microscope (SEM). A high resolution transmission electron microscope (HR-TEM) lattice image of the grown crystals showed a periodical structure with A-B stacking along the <0001> direction. These results indicated that the Li-based flux was useful for growing bulk 2H-SiC single crystals.
Crystalline Recovery after Activation Annealing of Al Implanted 4H-SiC
Authors: Hattori Ryo , Watanabe Tomokatsu , Mitani T. , Sumitani Hiroaki , Oomori Tatsuo
Published: March 2009

Crystalline recovery mechanism in the activation annealing process of Al implanted 4H-SiC crystals
were experimentally investigated. Annealing temperature and annealing time dependence of acceptor
activation and activated hole’s behavior were examined. Poly-type recovery from the implantation
induced lattice disordering during the annealing was investigated. The existence of meta-stable
crystalline states for acceptor activation, and related scattering centers due to annealing is reported
To achieve 100% acceptor activation and to reduce strain after ion implantation, annealing at 2000°C
for 10 min. was required.
Influence of the Oxidation Temperature and Atmosphere on the Reliability of Thick Gate Oxides on the 4H-SiC C(000-1) Face
Authors: Grieb Michael , Peters Dethard , Bauer Anton J. , Friedrichs Peter , Ryssel Heiner
Published: March 2009

The reliability of thermal oxides grown on n-type 4H-SiC C(000-1) face wafer has been
investigated. In order to examine the influence of different oxidation atmospheres and temperatures
on the reliability, metal-oxide-semiconductor capacitors were manufactured and the different oxides
were characterized by C-V measurements and constant-current-stress. The N2O-oxides show the
smallest flat band voltage shift compared to the ideal C-V curve and so the lowest number of effective
oxide charges. They reveal also the lowest density of interface states in comparison to the other oxides
grown on the C(000-1) face, but it is still higher than the best oxides on the Si(000-1) face. Higher
oxidation temperatures result in smaller flat band voltage shifts and lower interface state densities.
Time to breakdown measurements show that the charge-to-breakdown value of 63% cumulative
failure for the N2O-oxide on the C(000-1) face is more than one order of magnitude higher than the
highest values measured on the Si(000-1) face. Therefore it can be concluded that a smaller density of
interface states results in a higher reliability of the oxide.
Annealing Temperature Dependence of the Electrically Active Profiles and Surface Roughness in Multiple Al Implanted 4H-SiC
Authors: Giannazzo Filippo , Roccaforte Fabrizio , Salinas Dario , Raineri Vito
Published: March 2009

In the present work, we systematically studied the effect of the annealing temperature
(from 1400 °C to 1650 °C) on the electrical activation of 4H-SiC implanted with multiple energy
(from 40 to 550 keV) and medium dose (1×1013 cm-2) Al ions. The evolution of the acceptor (NA)
and compensating donor (ND) depth profiles was monitored by the combined use of scanning
capacitance microscopy (SCM) and scanning spreading resistance microscopy (SSRM). We
demonstrated that the electrical activation of the implanted layer with increasing annealing
temperature is the result of the increase in the acceptor concentration and of the decrease in the
ND/NA ratio. Atomic force microscopy (AFM) morphological analyses indicated that the surface
quality is preserved even after the 1650 °C annealing process.
Stability Growth Condition for 3C-SiC Crystals by Solution Technique
Authors: Ujihara Toru , Maekawa Ryosuke , Tanaka Ryo , Sasaki Katsuhiro , Kuroda Kotaro , Takeda Yoshikazu
Published: March 2009

A solution growth of 3C-SiC was performed on (111)Si-face or )111(C-face of 3C-SiC seed crystal at around 1700 °C by dipping method. The polytype of the crystal grown on the Si-face immediately changed to 6H-SiC. On the other hand, 3C-SiC stably grew on the C-face except for a small number of 6H-SiC precipitates. The polytype transition phenomenon can be explained by the difference of the chemical potential and the solution-crystal interfacial energy between 3C-SiC and 6H-SiC. To grow a larger 3C-SiC crystal, we carried out a long-term growth for 30 hours on the C-face. In the first 10 hours, the polytype of the grown crystal was 3C-SiC. In the next 10 hours, however, the polytype changed from 3C-SiC to 6H-SiC. According to our studies, 6H-SiC tends to grow on 6H-SiC at around 1700 °C, while both of 3C-SiC and 6H-SiC can grow on 3C-SiC at around the same temperature. In this case, 6H-SiC grows on 6H-SiC precipitates and then the dominant polytype changes to 6H-SiC after several 6H-SiC precipitations. To grow 3C-SiC crystal stably, it is necessary to surpress completely the polytype transition by the growth on C-face at lower growth temperatures.
Backside Nickel Based Ohmic Contacts to n-Type Silicon Carbide
Authors: Ghandi Reza , Lee Hyung Seok , Domeij Martin , Zetterling Carl Mikael , Östling Mikael
Published: March 2009

This work focuses on Ni ohmic contacts to the C-face (backside) of n-type 4H-SiC
substrates. Low-resistive ohmic contacts to the wafer backside are important especially for vertical
power devices. Ni contacts were deposited using E-beam evaporation and annealed at different
temperatures (700-1050 °C) in RTP to obtain optimum conditions for forming low resistive ohmic
contacts. Our results indicate that 1 min annealing at temperatures between 950 and 1000 °C
provides high quality ohmic contacts with a contact resistivity of 2.3x10-5 Ωcm2. Also our XRD
results show that different Ni silicide phases appear in this annealing temperature range.
Isotropic Etching of SiC
Authors: Stauden Thomas , Niebelschütz Florentina , Tonisch Katja , Cimalla Volker , Ecke Gernot , Haupt Christian , Pezoldt Joerg
Published: March 2009

Isotropic etching of silicon carbide was achieved using a capacitive coupled parallel plate
reactor in plasma etching mode and SF6 at elevated substrate temperatures. It was observed to be
remarkable at substrate temperatures above 350°C. The influence of chamber pressure, masking
materials, rf-power and substrate temperature were analyzed. Thereby, 8.5° off-axis oriented 4HSiC
wafers exhibit a larger vertical and lateral etching rate compared to on-axis oriented SiC
wafers. Additionally, the erosion of nitrogen containing masking material results in a reduction of
the etching rates.