bluuebunny/crossref_metadata_2025 huggingface dataset:
Efficacy of Triamcinolone Hexacetonide versus Methylprednisolone Acetate Intraarticular Injections in Knee Osteoarthritis: A Randomized, Double-blinded, 24-week Study
Authors: Lomonte Andrea Barranjard Vannucci , de Morais Marina Gonçalves Veras , de Carvalho Lina Oliveira , Zerbini Cristiano Augusto de Freitas
Published: July 2015

Objective.

Intraarticular (IA) corticosteroid injections are broadly used in knee osteoarthritis (OA); however, the best corticosteroid agent is not well defined. The aim of the present study was to compare the efficacy of triamcinolone hexacetonide (TH) and methylprednisolone acetate (MA) injections in knee OA.

Methods.

Patients with symptomatic knee OA and Kellgren-Lawrence grade II or III were randomized to receive 40 mg of IA TH or MA. Evaluations were performed at 4, 12, and 24 weeks. The primary outcome was a change in the patient’s assessment of pain by visual analog scale from baseline to Week 4. Secondary outcomes included a global assessment of the disease by patients and physicians, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Lequesne index (LI), and Outcome Measures in Rheumatology Clinical Trials and Osteoarthritis Research Society International (OMERACT-OARSI) criteria of response. Generalized estimating equations were used in statistical analysis.

Results.

The intention-to-treat population included 100 patients; 50 in each study arm. A significant improvement in pain was observed at Week 4 for both groups (p < 0.0001), with no difference between them (p = 0.352). This improvement was sustained up to Week 24. A significant improvement from the baseline was observed for both the patient’s and the physician’s global assessments, WOMAC questionnaire, and LI, with no differences between the groups. Improvements in the secondary outcomes were sustained during the study. The OMERACT-OARSI criteria of response was achieved by 74% and 72% of patients in the TH and the MA groups, respectively.

Conclusion.

Both IA therapies are equally effective, and improvement in pain and function can be sustained for up to 24 weeks.Controlled-trials.comidentifier:ISRCTN15077843.
Into the ears, through the head, out on the lips. How listening errors can trigger new instances of palatalisation
Authors: Glain Olivier
Published: July 2015

Le présent article a une double visée. Il introduit tout d’abord des changements de sons qui ont été notés depuis quelques années dans différents pays anglophones et se propose de les rassembler sous une appellation commune. Ce qui permet de faire le lien entre ces divers changements est la production commune de palato-alvéolaires, phénomène qui s’inscrit dans le prolongement d’une tendance historique à la palatalisation en langue anglaise. Dans un deuxième temps, l’accent est mis sur l’un des paramètres pouvant en partie expliquer l’évolution linguistique, celui des erreurs de perception qui peuvent entraîner un changement dans la représentation phonologique d’items lexicaux chez certains récepteurs, et donc conduire à un véritable changement de son. La question de la diffusion d’une innovation à la communauté linguistique, c’est-à-dire l’actuation du changement, est ensuite abordée. L’auteur propose une hypothèse selon laquelle les grandes mutations sociales et idéologiques qui ont caractérisé le monde anglo-saxon après la Seconde Guerre Mondiale ont favorisé le développement de palato-alvéolaires à l’origine non-standard.
Genre et pronoms en anglais
Authors: Cotte Pierre
Published: July 2015

The grammatical category of gender, when it is ‘natural’, is a semantic property of linguistic units with independent grammatical functions. In this paper the gender of English pronouns is examined, with special emphasis on personal gender. It is argued that the nominal bases of the indefinite pronouns someone, somebody or something signify genders, not just categories. It is also argued that the interrogative pronouns who and what are subsequent to these pronouns logically. The paper finishes with some remarks about the affinities between personal gender and indefiniteness on one hand and sex-based gender and definiteness on the other. These point to a single encompassing system of gender and nominal determination.
Anaphore et fonction attribut du sujet : le cas de SO
Authors: Johansson-Manoury Elisabet
Published: July 2015

This article deals with a particular kind of subject complement, and in so doing discusses the notions of “defining feature” and “subjective feature” in utterances where the adverb SO acts as an anaphora for the subject complement. The feature referred to by SO qualifies the subject, thus constituting a defining feature or a subjective qualification of the subject. The problem under scrutiny is the fact that I have stated elsewhere that the marker SO is linked to the notion of alterity: a feature of subjective origin involves the notion of alterity whereas a defining feature normally does not. In order to make these traits stand out the marker SO is opposed to one and Ø.
Sort of/kind of : réalisations prosodiques
Authors: Horgues Céline
Published: July 2015

This paper aims to explore the relationship between prosodic form and the different linguistic functions of the sort of/kind of constructions. Certain previous research has given a simplistic outlook on this relationship, where the prosodic correlates systematically cue the two main types of functions: the nominal use (Type use) is associated with accentual prominence realised with a full form of sort/kind whereas the discourse marker use is realised as non-prominent and phonologically reduced. However, the analysis of a few counter-examples to this generalisation will show that prosody should not be regarded as a simple reflexion of the linguistic function of sort of/kind of but rather as a linguistic marker in its own right contributing to the expression of discourse-specific meanings.
L’Empathie comme base de réflexion sur l’identité des marqueurs HAVE et WANT
Authors: Muller Philippe
Published: July 2015

In the wake of previous papers from French linguists who used the word “empathy” to describe the operators AVOIR and HAVE, it is suggested that this notion should be conceived of as an interpretation process connected with the localization operation as defined in enunciative theories. It is proposed that this process hinges on the speaker and co-speaker assessing the necessity of establishing a relation between a located term and a locator through an operator. Such a relation must bring about a (re)qualification of the locator capable of justifying its status as the central topic in the situation being described. This state of affair creates a whole-part relationship between the redefined locator and the situation itself whereby the latter undergoes a differentiation process. It is then suggested that empathy is what lets the HAVE-predication sometimes be analysed as a subjectified existential phrase. It is also what really underlies the recent claims about WANT concerning the development of volition out of a notion of deficit. This process seems to remain synchronically relevant for that marker and complements the concept of “intentionality” that is used in Culioli’s speaker-centred approach and which could serve as a basis for distinguishing between WANT and NEED. Finally, it is shown that the empathy associated with WANT can be advantageously utilised in discourse in a specific narrative pattern, that of the “circle story”.
When Journalism Met the Internet
Authors: Dillon Mike
Published: July 2015

American news organizations have long been criticized for failing to anticipate, appreciate and exploit the Internet as it became a fact of daily life in the mid-1990s. This chapter explores and analyzes the lack of planning that stymied the development of journalism on the Web and cast doubt on the viability of traditional public-service journalism with its enduring values of accuracy, fairness and advocacy. Specifically, the essay documents and analyzes the online debuts of two venerable “old media” news outlets (The New York Times and The Los Angeles Times) and two “new media” Web news outlets (Salon and Slate) in the mid-1990s by exploring the claims they made about their aims, purposes and expectations as they introduced themselves to the public via their salutatory editorials. It is a cautionary tale for a digital world that reconfigures itself in ever-quickening cycles.
Tool Orchestration in e-Collaboration
Authors: Magnisalis Ioannis , Demetriadis Stavros
Published: July 2015

In this study the authors start by highlighting the lack of a “tool orchestration” framework in e-collaboration environments (either for work or learning purposes). To address this issue, they propose the MAPIS3 software architecture to efficiently manage the key problem in tool orchestration, which is the efficient data transfer among various tools used in e-collaboration activities. To evaluate their proposal, they present a case study of a flexible e-collaboration scenario that cannot be implemented automatically with any known architectures or tools. This scenario entails transfer and processing of students' collaboration data emerging originally in a chat tool to an IMS-LD compatible application (“player”) and, finally, to a Moodle installment forum. The overall implementation was evaluated both from the developer's and the student's perspective. Results indicate that seamless data flow establishing tool orchestration can be achieved by the proposed approach in a cost-efficient and flexible manner. Moreover, the authors highlight and discuss how data flow and flexible management supported by the architecture may have a profound impact on the quality of users' collaboration.
Born Fast, Die Young?
Authors: Han Bo
Published: July 2015

How to keep users has become the most desirable knowledge to social network site (SNS) managers. In the current study, the author proposes a user's SNS continuance model by incorporating the information system continuance model and the impression management theory. The author finds that a user's actualization of the hoped for possible self and perceived informativeness of an SNS are two critical factors that can significantly positively influence the user's perceived usefulness of the SNS, perceived enjoyment on the Web site, and his or her SNS continuance intention. The author suggests that these findings provide several practical implications to SNS management and development.
Heat Treatment of Ultrafine Grained AA 6061 Consolidation by Equal Channel Angular Pressing
Authors: Pramono Agus , Kollo Lauri , Veinthal Renno , Kallip Kaspar , Gomon Jaana Kateriina
Published: July 2015

During the last decade Equal Channel Angular Pressing (ECAP) has emerged as a widely known procedure for the fabrication of ultrafine grained metals and alloys. This review examines recent developments related to the use of ECAP for grain refinement. In the current study the part of capsules wrapper for powder material to be compressed where the powder AA6061 was wrapped in copper sheet and heated at a temperature of 400 OC in hot pressed under the pressure of 400 MPa. Afterward the powder in solid condition was cooled in the air and then does analysis characterization. The sample results of AA6061 are ECAP as is and heat treatment with type Anneal and Artificial Aging (T6) where heat treatment is heated at a temperature of 530 °C for 1 h followed by heating at a temperature of 100 °C for one day and the other for heating at a temperature of 415°C for 2.5 hours followed by heating at a temperature of 177 °C for 8 hours. This paper explains the characteristics of each sample where analyses are based on the mechanism of properties to determine how much change of mechanical properties and microstructure. Heat treatment effect on grain coarsening so that the mechanical properties can be engineered.
Triptolide: A Critical Review on Antiangiogenesis in Cancer and Scope in Therapeutics
Authors: Naila Ahmed , Zhang Ya Fang
Published: July 2015

Triptolide (TPL) is a traditional Chinese medicine and an active component of a Chinese herbTripterygium wilfordiiF. (Celastraceae). Triptolide has been used to treat a variety of ailments, including rheumatoid arthritis, nephritic syndrome and Lupus erythematosus. It is also a strong antitumor agent. Several angiogenesis assays in numerous research studies have shown that triptolide is an angiogenesis inhibitor. Numerous preclinical studies have shown that TPL inhibits cell proliferation, induces apoptosis and limits tumor metastasis. TPL also has a synergistic action with other treatment methods whereby, it enhances the effects of other antitumor treatments, as studied in various cancer cell lines. This review summarizes the recent developments and discussion of antiangiogenic mechanisms of TPL in cancer, brief outline of its clinical trials and its future in cancer therapeutics.
Effects of Number of Porous Insert, Spindle Speed and Gap Thickness on Characteristics of a Partially Porous Aerostatic Journal Bearing
Authors: Huang Te Yen , Hsu Shao Yu , Shen Song Chiang , Lin Sheam Chyun , Chou Ta Hsin
Published: July 2015

The effects of the rotating speed of the spindle, the number of the porous medium inserted into the partially porous aerostatic journal bearing and the thickness of the bearing gap on the characteristics of the bearing such as the pressure distribution, the load carrying capacity and the stiffness of the bearing were studied. Based on the finite volume method and the pressure-velocity coupling scheme of the SIMPLE algorithm with the standard k-ε turbulent model, the CFD software was used to solve the Navier-Stokes equations to calculate the pressure field in the bearing gap. The computed results revealed the faster the spindle rotated, the higher the gap pressure. As the gap thickness increased, the gap pressure, the load carrying capacity and the stiffness of the bearing decreased. The more the porous inserts, the higher the gap pressure and the load carrying capacity, but the less the bearing stiffness would be.
Study of Al Incorporation in Chemical Vapor Deposition of p-Doped SiC
Authors: Segal A.S. , Karpov S.Yu. , Lobanova A.V. , YAKOVLEV Eugene , Hara K. , Naito Masami
Published: July 2015

Quasi-thermodynamic model of SiC doping with Al in CVD from C3H8, SiH4, and Al (CH3)3 on the Si-face is developed. The model is validated by quantitative agreement of calculated and experimental data on the Al concentration in SiC as a function of temperature, pressure, SiC growth rate, and TMAl flow rate. The model is shown to be consistent with the site competition mechanism of Al incorporation into SiC.
Residual Stress Analysis of Indentation on 4H-SiC by Deep-Ultraviolet Excited Raman Spectroscopy
Authors: Kozu Tomomi , Yamaguchi Makoto , Fujitsuka Masayuki , Milikofu Olga , Nishida Ken
Published: July 2015

In this work, we analyze residual stress on 4H-SiC with Raman spectroscopy that excitation wavelength is deep ultraviolet (DUV) laser 266nm. The residual stress area is created by Vickers Hardness test technique and the area is measured by 2D DUV Raman map. The result is different from visible light excited Raman, because DUV light penetration is shallower than visible light. DUV Raman signal has exactly brings only the sample surface information. We present the advantage of DUV excited Raman to analyze sample surface.
Conductivity Compensation in CVD-Grown n-4H-SiC under Irradiation with 0.9 MeV Electrons
Authors: Kozlovski Vitalii V. , Lebedev Alexander A. , Bogdanova Elena V. , Seredova Natalia. V.
Published: July 2015

Effects of electron irradiation in n-4H-SiC have been studied by the methods of the capacitance--voltage characteristics and photoluminescence. It was found that the carrier removal rate (Vd) reached a value of ~0, 25 cm- 1. Full compensation of samples with an initial concentration of 1.2 1015 cm -3 was observed at doses of about 5 1015 cm -2. Simultaneously with the increase in the degree of compensation, the intensity of the “defect luminescence”, typical of 4H SiC, became higher. The physical compensation mechanisms were analyzed for the samples under study.
Improvement of Surface Morphology by Solution Flow Control in Solution Growth of SiC on Off-Axis Seeds
Authors: Umezaki Tomonori , Koike Daiki , Harada Shunta , Ujihara Toru
Published: July 2015

The solution growth of SiC on an off-axis seed is effective on the reduction of threading dislocations. We proposed a novel method to grow a SiC crystal on an off-axis seed by top-seeded solution growth (TSSG). In our previous study, a unidirectional solution flow above a seed crystal is effective to suppress surface roughness in the growth on the off-axis seed. However, it is difficult to apply the unidirectional flow in an axisymmetric TSSG set-up. In this study, the unidirectional flow could be achieved by shifting the rotational axis away from the center of the seed crystal. As a result, the smooth surface was obtained in the wider area where the solution flow direction was opposite to the step-flow direction.
Photoluminescence Study of Oxidation-Induced Stacking Faults in 4H-SiC Epilayers
Authors: Miyano Yutaro , Yagi Shuhei , Hijikata Yasuto , Yaguchi Hiroyuki
Published: July 2015

We have investigated the effect of thermal oxidation on stacking faults (SFs) in 4H-SiC epilayers using photoluminescence imaging. We found that a comb-shaped dislocation array was deformed by thermal oxidation and that SFs were formed on both sides of the comb-shaped dislocation array by a laser irradiation. Transmission electron microscopy has been performed in the comb-shaped dislocation array to observe the stacking pattern of SF near the dislocation. As a result, the SF turned out to be a single Shockley SF (1SSF). We also found that line-shaped faults perpendicular to the off-cut direction were formed during oxidation and were stretched with oxidation time. Moreover, triangle-shaped SFs were formed/expanded from the line-shaped faults by a laser irradiation. The characteristics of these line-shaped faults were discussed.
Simple Models for Stacking-Fault Formations in 4H-SiС Epitaxial Layer
Authors: Kitabatake Makoto
Published: July 2015

Simple models for Shockley-type stacking-fault formations during 4H-SiC epitaxial growth are proposed. The model consists of the accidentally-faulted mis-stacking and the Shockley single-gliding events. At first, the mis-stacking event caused by imperfect step-flow growth is considered. Then the single-gliding event is followed to make more stable stacking sequences. Simple single-gliding is considered rather than complicated double, triple, or quadruple Shockley gliding. All possible mis-stacking and single-gliding events are considered. All of the reported Shockley-type SFs are derived without excess and deficiency from the proposed models.
4H-SiC Defects Analysis by Micro Raman Spectroscopy
Authors: Piluso Nicolo’ , Camarda Massimo , Anzalone Ruggero , La Via Francesco
Published: July 2015

Recently, a new Micro-Raman technique has been used to detect extended defects in 4H-SiC homoepitaxy. The method is based on the local increase of free carriers in undoped epitaxies (n < 1016 at/cm-3) produced by a high power laser. The Longitudinal optical Raman mode (LO) is coupled with the electronic plasma generated by the laser pumping; such a Raman signal is sensitive to crystallographic defects that lead to trapping (or dispersion) of the free carriers which results in a loss of coupling. The monitoring of the LOPC allows determining the spatial morphology of extended defects. The results show that the detection of defects via the induced-LOPC (i-LOPC) is totally independent from the stacking fault photoluminescence signals that cover a large energy range up to 0,7eV thus allowing for a single-scan simultaneous determination of any kind of stacking fault. Also, the i-LOPC method shows the connection between the carrier concentration and the carrier lifetime for undoped film, obtaining meaningful information related to electrical properties of the film, and demonstrating that this technique is a fast, reliable and powerful method to characterize most of crystallographic defects (extended and point-like defects) in the semiconductor field.
Structural Perfection of Silicon Carbide Crystals Grown on Profiled Seeds by Sublimation Method
Authors: Mokhov Evgeniy , Nagalyuk Sergey , Soltamov Victor A.
Published: July 2015

— The distribution of extended defects in silicon carbide (SiC) crystals grown on profiled seeds by the sublimation (physical vapor transport) method has been studied by optical microscopy in combination with chemical etching and AFM. It is established that free lateral growth on protruding relief elements (mesas) is accompanied by a sharp decrease in the density of threading dislocations and micropipes. The decreased density of dislocations is retained after growing a thick layer that involves the overgrowth of grooves that separated individual mesas.
Research on Solvent Composition for Different Surface Morphology on C Face during 4H-SiC Solution Growth
Authors: Xiao S. , Hara Natsumi , Harada Shunta , Murayama Kenta , Aoyagi Kenta , Sakai Takenobu , Ujihara Toru
Published: July 2015

Surface morphology of the SiC crystal grown on the C face of the 4H-SiC seed crystal by TSSG method using pure Si, Si-1at%Ti-C, Si-5at%Ti-C and Si-20at%Ti-C solvents was investigated. The surface morphology of the crystal grown from pure Si solvent was smooth. By the addition of Ti to the solvent, the surface morphology became rougher. The RMS value is not proportional to the concentration of Ti. The formation of macrosteps with several micrometers was observed when the addition of Ti increased to 5at% indicating the possibility of the threading screw dislocation conversion on the C face of the 4H-SiC crystal.
Effect of Porous Graphite for High Quality SiC Crystal Growth by PVT Method
Authors: Lee Hee Jun , Lee Hee Tae , Shin Hee Won , Park Mi Seon , Jang Yeon Suk , Lee Won Jae , Yeo Im Gyu , Eun Tai Hee , Kim Jang Yul , Chun Myoung Chul , Lee Si Hyun , Kim Jung Gon
Published: July 2015

The effect of the porous graphite plate above the source material on properties of silicon carbide (SiC) crystals grown by Physical Vapor Transport method has been investigated. The porous graphite plate was inserted on source powder to produce a more C-rich for the polytype stability of 4H-SiC crystal and a uniform radial temperature gradient. The dendrite structure obtained from SiC source powder in the crucible with porous graphite plate was more densely formed than that in the conventional crucible. The crystal quality of 4H-SiC single crystals grown in porous graphite inserted crucible was revealed to be better than that of crystal grown SiC crystals in the conventional crucible.
Direct Observation of Dielectric Breakdown at Step-Bunching on 4H-SiC
Authors: Mori Yuki , Matsumura Mieko , Hamamura Hirotaka , Mine Toshiyuki , Shima Akio , Yamada Renichi , Shimamoto Yasuhiro
Published: July 2015

The mechanism of dielectric breakdown of oxide on step-bunching of 4H-silicon carbide (SiC) was investigated. Comparing the surface morphology obtained before forming metal-oxide-semiconductor (MOS) capacitor and optical emission on the capacitor under electrical stress, it was cleared that current concentrates on step-bunching and it often caused preferential dielectric breakdown. Based on TEM analysis and the observation of time dependence of emission under the stress, a new model was proposed to explain the dielectric breakdown on step-bunching.
Influence of Phosphorus Implantation on Electrical Properties of Al/SiO2/4H-SiC MOS Structure
Authors: Krol Krystian , Sochacki Mariusz , Turek Marcin , Żuk Jerzy , Borowicz Pawel , Teklińska Dominika , Konarski Piotr , Miśnik Maciej , Domanowska Alina , Michalewicz Anna , Szmidt Jan
Published: July 2015

This paper describes the effects of phosphorus implantation into n-type 4H-SiC substrate prior to standard dry oxidation process. Phosphorus incorporation has been reported to be one of the most efficient means of increasing SiC MOSFET field mobility however the physical basis of this phenomenon is still not clear. The aim of this research is to investigate the influence of phosphorus implantation on trap density profile close to conduction band of silicon carbide and to gain understanding of physical processes responsible for observed trap density improvement in phosphorus related oxidation technologies of silicon carbide.
Comparison of Different Novel Chip Separation Methods for 4H-SiC
Authors: Dohnke Karl Otto , Kaspar Korbinian , Lewke Dirk
Published: July 2015

Mechanical blade dicing is a state-of-the-art technique for the chip separation of SiC devices. Due to the hardness of SiC this technique suffers from low feed rate and high wear of the diamond coated dicing blade, resulting in the risk of uncontrolled tool breakage during the dicing process. With the upcoming transition to 150 mm diameter of SiC wafers this technique will most probably reach its limit. For dicing SiC wafers of those diameters on a productive scale three alternative dicing technologies are considered in this paper: ablation laser dicing, Stealth Dicing and Thermal Laser Separation. All these methods are based on laser processing. The benefits of these technologies are discussed in detail and compared to the classical mechanical diamond blade dicing, including a brief summary of first experimental results on each of the three laser dicing technologies.
Improvement of I-V Characteristics of Schottky Barrier Diode by 4H-SiC Surface Planarization
Authors: Fujiwara Hirokazu , Onogi A. , Katsuno Takashi , Morino Tomoo , Endo Takeshi , Sano Yasuhisa
Published: July 2015

Leakage current points in 4H-SiC Schottky barrier diodes (SBDs) were found to be in the same location as rough surface morphologies. Rough surfaces after activation annealing at the Schottky interface of diodes were removed by chemical mechanical polishing (CMP) or catalyst-referred etching (CARE). As a result, this study succeeded in reducing the leakage current and barrier height variation of 1.2 kV SBDs by eliminating surface roughness.
Ion-Induced Anomalous Charge Collection Mechanisms in SiC Schottky Barrier Diodes
Authors: Makino Takahiro , Deki Manato , Onoda Shinobu , Hoshino Norihiro , Tsuchida Hidekazu , Ohshima Takeshi
Published: July 2015

The charge induced in SiC-SBDs with different epi-layer thicknesses by ion incidence was measured to understand the mechanism of heavy-ion-induced anomalous charge collection in SiC-SBDs. SiC SBD of which epitaxial-layer thicknesses is close to ion range show larger anomalous charge collection than SBD with thicker epi-layer although the former one has lower electric field than the later one. The gains of collected charge from the SBDs suggest that the impact ionization under 0.16 - 0.18 MV/cm of the static electric field in depletion layer is not dominant mechanisms for the anomalous charge collection. It is suggested that the epitaxial-layer thickness and ion-induced transient high electric field are key to understand the anomalous charge collection mechanisms in SBDs.
Industrial Approach for Next Generation of Power Devices Based on 4H-SiC
Authors: Saggio Mario , Guarnera Alfio , Zanetti Edoardo , Rascunà Simone , Frazzetto Alessia M. , Salinas Dario , Giannazzo Filippo , Fiorenza Patrick , Roccaforte Fabrizio
Published: July 2015

Silicon Carbide metal-oxide-semiconductor field effect transistor (4H-SiC MOSFET) can be considered as the next revolution in power electronics applications. However, a wide market introduction of 4H-SiC MOSFET requires a special focus on device reliability and simplicity of use to replace Silicon switches in existing applications. This paper describes STMicroelectronics (STM) approach to define methodology and design solutions able to guarantee the end-users and to drive their choice toward 4H-SiC MOSFET as an ideal power component.
Exact Characterization of Threshold Voltage Instability in 4H-SiC MOSFETs by Non-Relaxation Method
Authors: Sometani Mitsuru , Okamoto Dai , Harada Shinsuke , Ishimori Hitoshi , Takasu Shinji , Hatakeyama Tetsuo , Takei Manabu , Yonezawa Yoshiyuki , Fukuda Kenji , Okumura Hajime
Published: July 2015

In this work, we investigated the methods that measure the threshold voltage (Vth) instability without relaxation of the gate stress during the Vth measurement. We propose a non-relaxation method that demonstrates exact Vth shifts compared with conventional methods that are not as accurate. In the non-relaxation method, the constant gate-source voltage (Vgs) is continuously applied as a gate stress while the drain voltage (Vds) shift required to maintain a constant drain current (Id) is measured. Then, the Vds shift is converted to a Vth shift. The Vth shift values measured by the non-relaxation method are larger than those measured by the other methods, which means that the non-relaxation method can very accurately measure the Vth shift.
Next-Generation Planar SiC MOSFETs from 900 V to 15 kV
Authors: Allen Scott , Pala Vipindas , VanBrunt E. , Hull Brett , Cheng Lin , Ryu S. , Richmond Jim , O’Loughlin M. , Burk Albert A. , Palmour J.
Published: July 2015

A family of planar MOSFETs with voltage ratings from 900 V to 15 kV are demonstrated. This family of planar MOSFETs represents Cree’s next generation MOSFET design and process, in which we continue to refine and evolve device design and processing to further shrink die sizes and enhance device performance. At voltage ratings of 3.3 kV and above, the specific on-resistance of the MOSFETs is approaching the theoretical limit. MOSFET switching performance in a clamped inductive switching circuit for the full range of voltage ratings is also demonstrated. Finally, improved threshold voltage and body diode stability under long-term stresses are presented.
Reliable 4H-SiC MOSFET with High Threshold Voltage by Al2O3-Inserted Gate Insulator
Authors: Shima Akio , Watanabe Kikuo , Mine Toshiyuki , Tega Naoki , Hamamura Hirotaka , Shimamoto Yasuhiro
Published: July 2015

We investigated the effect of an Al2O3 insertion layer in the gate insulator to make Vth higher and to improve the transconductance Gm in a SiC-MOSFET. Insertion of the Al2O3 layer successfully enlarged Vth by about 4 V. The Vth difference sub-threshold Id-Vg characteristics measured by sweeping the gate voltage bi-directionally indicates that insertion of the Al2O3 layer decreased the number of traps of electrons in the gate insulator. Due to this decrease, device reliability in long-term operation was improveed by smaller Vth shift in PBTI. It was also found that the insertion of the Al2O3 layer improved Gm by two times. Using this gate insulator, we succeeded in fabricating 600 V 20 A-class vertical SiC DMOSFETs with a high Vth (>5 V) and low Ron of 3 mΩcm2.
Effect of Fixed Oxide Charges and Donor-Like Interface Traps on the Breakdown Voltage of SiC Devices with FGR and JTE Terminations
Authors: Yen Cheng Tyng , Hung Hsiang Ting , Hung Chien Chung , Lee Chwan Ying , Lee Lurng Shehng , Huang Yao Feng , Yang Tzu Ming , Cheng Chi Yin
Published: July 2015

The influences of positive fixed oxide charges and donor-like interface traps on breakdown voltages of SiC devices with FGR and JTE terminations were studied. The breakdown voltages of devices with both FGR and JTE terminations were found to degrade when the level of fixed oxide charges overs 1×1012 cm-2 due to enhancement of junction curvature by fixed oxide charges. The introduction of donor-like interface traps at the interface shows similar behaviors as fixed positive charges, suggested that both fixed oxide charges and interface traps should be taken into account when one optimizes device designs and processes.
Electrical Characterization of 3C-SiC Lateral MOSFETs Fabricated on Heteroepitaxial Films Including High Density of Defects
Authors: Watanabe Yukimune , Kawana Noriyasu , Horikawa Tsuyoshi , Kamimura Kiichi
Published: July 2015

We have fabricated lateral MOSFETs on heteroepitaxial 3C-SiC films included high density of defects. Electrical characteristics of 3C-SiC MOSFETs and their temperature dependence were measured to discuss effects of defects on the electrical characteristics. A field effect mobility of 156 cm2/Vs was obtained at room temperature. After applying a drain voltage of 10 V or higher, the drain current - gate voltage curve shifted toward the positive gate voltage. This shift was caused mainly by the charge trapping in the gate oxide. The light emission was observed on the surface of the active MOSFET. The spatial distribution of the emission light from MOSFETs indicated that the charge was generated at the source edge of the gate channel.
Effect of Bulk Potential Engineering on the Transport Properties of SiC MOSFETs: Characterization and Interpretation
Authors: Uhnevionak Viktoryia , Burenkov Alex , Strenger Christian , Ortiz Guillermo , Mortet Vincent , Bedel-Pereira Elena , Cristiano Fuccio , Bauer Anton J. , Pichler Peter
Published: July 2015

The effect of bulk potential engineering on the transport properties in the channel of SiC MOSFETs has been studied. For this purpose, n-channel SiC MOSFETs have been manufactured with different background doping concentrations and characterized electrically at room temperature by current-voltage as well as by Hall-effect measurements. To interpret the measurements performed, numerical simulations have been carried out using Sentaurus Device of Synopsys. The main finding of the simulation analysis is that the change in the depth of the band-bending has to be considered to explain the doping dependence of SiC MOSFET characteristics.
Gate Oxide Reliability of 4H-SiC V-Groove Trench MOSFET with Thick Bottom Oxide
Authors: Hiyoshi Toru , Masuda Takeyoshi , Saito Yu , Wada Keiji , Tsuno Takashi , Mikamura Yasuki
Published: July 2015

The authors reported the DMOSFETs fabricated on the 4H-SiC(0-33-8) in ECSCRM2012 and the novel V-groove MOSFETs, having (0-33-8) on the trench sidewall in ICSCRM2013. In this paper, we applied both the thick bottom oxide and the buried p+ regions to the V-groove MOSFETs for the protection of the trench bottom oxide. The V-groove MOSFET showed the low specific on-resistance of 3.2 mΩcm2 and the high blocking voltage of 1700 V on the bounty of the high channel mobility and the gate oxide protection, respectively. We also tested the gate oxide reliability of the V-groove MOSFET by constant-voltage stress TDDB measurement. The charge-to-breakdown was 18.0 C/cm2 at room temperature and 4.4 C/cm2 at 145°C. In addition, the stability of the threshold voltage was characterized with the VMOSFETs.
Introduction of Depletion Stopper for Reduction of JFET Resistance for 4H-SiC Trench MOSFET
Authors: Kagawa Yasuhiro , Tanaka Rina , Fujiwara Nobuo , Sugawara Katsutoshi , Fukui Yutaka , Miura Naruhisa , Imaizumi Masayuki , Nakata Shuhei , Yamakawa Satoshi
Published: July 2015

This paper investigates thereduction of parasitic resistance (JFET resistance) betweenthe p-well and the grounded p-type gate-oxide protection layer (BPW)of a trench-gate SiC-MOSFET. Forming a deeptrench is a way to reducethe JFET resistance, but this consequently leads to high electric field at thebottom oxide. In order to improve the trade-off between the specific on-resistance (Ron,sp) and the maximum bottom oxide electric field (Eox), wenewly developed a trench-gate SiC-MOSFET with an n-type region, named DepletionStopper (DS), formed under the entire p-welllayer. As aresult of fabrication, Ron,sp of the trench-gate SiC-MOSFET with DS is70 % lower than that without DS at a trench depth (dt) of about 1.5 mm. The dtof the trench-gate SiC-MOSFET with DS can be designed 25 % shallower than thatwithout DS at a Ron,sp of about 3.0 mWcm2.Therefore, it can reduce the JFET resistance and allow to shrinkthe trench depth. Optimizing the parametersof DS, the structure having DS is an effective means of reducing the JFETresistance, while reducing Eox by minimizing the depth of the trench.
Low Rons in 3kV 4H-SiC UMOSFET with MeV Implanted Buried P-Base Region
Authors: Harada Shinsuke , Kato Makoto , Shinozaki Megumi , Kobayashi Yusuke , Ariyoshi Keiko , Kojima Takahito , Sometani Mitsuru , Senzaki Junji , Tanaka Yasunori , Okumura Hajime
Published: July 2015

3kV UMOSFET with buried p-base regions was developed to realize the low on-resistance with low electric field in the gate oxide for off-state. The buried p-base region was formed simultaneously with the p-base region by utilizing MeV ion implantation. Influence by the structural parameter such as cell geometry and space between the buried p-base region and the trench gate was investigated. The hexagonal cell with high channel density exhibits an extremely low on-resistance of 6.8 mΩcm2 with threshold voltage of 5.0 V at room temperature.
Electrical Characterization of a 4H-SiC JFET Wafer: DC Parameter Variations for Extreme Temperature IC Design
Authors: Neudeck Philip G. , Chen Liang Yu , Spry David J. , Beheim Glenn M. , Chang Carl W.
Published: July 2015

This work reports DC electrical characterization of a 76 mm diameter 4H-SiC JFET test wafer fabricated as part of NASA’s on-going efforts to realize medium-scale ICs with prolonged and stable circuit operation at temperatures as high as 500 °C. In particular, these measurements provide quantitative parameter ranges for use in JFET IC design and simulation. Larger than expected parameter variations were observed both as a function of position across the wafer as well as a function of ambient testing temperature from 23 °C to 500 °C.
4H-SiC VJFETs with Self-Aligned Contacts
Authors: Zekentes Konstantinos , Stavrinidis Antonis , Konstantinidis George , Kayambaki Maria , Vamvoukakis Konstantinos , Vassakis Emmanouil , Vasilevskiy Konstantin , Horsfall Alton B. , Wright Nick G. , Brosselard Pierre , Niu Shi Qin , Lazar Mihai , Planson Dominique , Tournier Dominique , Camara Nicolas , Bucher Matthias
Published: July 2015

Trenched-implanted-gate 4H–SiC vertical-channel JFET (TI-VJFET) have been fabricated with self-aligned nickel silicide source and gate contacts using a process sequence that greatly reduces process complexity as it includes only four lithography steps. The effect of the channel geometry on the electrical characteristics has been studied by varying its length (0.3 and 1.2μm) and its width (1.5-5μm). The transistors exhibited high current handling capabilities (Direct Current density 330A/cm2). The output current reduces with the increase of the measurements temperature due to the decrease of the electron mobility value. The voltage breakdown exhibits a triode shape, which is typical for a static-induction transistor operation.
Bulk Thickness and Short Circuit Capacity of a 1200V 4H-SiC VJFET
Authors: Niu Shi , Berthou Maxime , Tournier Dominique
Published: July 2015

In many power electronic inverters, the gate drive failure may put the switch normally-on in short-circuit (SC) risk. The high power density generated thus leads rapidly to the transistor failure. This paper presents our study via electro-thermal simulation of a 1200 V JFET under short circuit. It provides deep insight of physical phenomena present in the JFET during the short-circuit and will allow further improvements and understanding of it.
IR Lock-In Thermography Analysis to Evidence Dynamic Mis-Behavior of SiC Device Prototypes
Authors: Chevalier Florian , Leon Javier , Perpiña X. , Tournier Dominique , Jordá Xavier , Montserrat Josep , Godignon Philippe
Published: July 2015

This paper deals with the geometry of a high voltage (1200 V) vertical JFET made with 4H silicon carbide, inspired by SIT or commercial solutions like Semisouth's one (principle exposed in Fig. 1). A first layout was designed allowing an easy integration of a free-wheeling diode. Indeed with the maturity of SiC JFET fabrication process, nowadays' trend is the high integration level of a complete power electronics system. This paper will focus on the distribution of the gate potential or the source current across the device and the relation that could be done with the switching delay. The measurements start with the classical I–V static characterization from room temperature till 225°C. After packaging the best dies, the switching behavior is studied. Gate bias and temperature dependence is also investigated. In order to fully understand the conducting/blocking or switching mechanisms, some further measurements using lock-in infrared thermography (LIRT) technique was led. Thus, with this complete characterization methodology the device layout can be improved.
Improvement of the Current Gain Stability of SiC Junction Transistors
Authors: Sundaresan Siddarth G. , Grummel Brian , Hamilton Dean , Singh Ranbir
Published: July 2015

SiC Junction Transistors (SJTs) with 1900 V Drain-Source breakdown voltages, current gain (hFE) higher than 120 and low on-resistance of 22 mΩ (3.5 mΩ-cm2) are reported in this paper. SJTs with a pre-stress hFE of 90 suffer only a 10% reduction of the hFE after 190 hours under a 200 A/cm2 DC current stress at a TJ of 125°C, while a similar stress on earlier generation SJTs resulted in over 25% hFE reduction in only 25 hours. SJT die with pre-stress hFE in the range of 120-125 show absolutely no current gain degradation even after a 300°C/ 2 hour stress at 60 A/cm2 DC drain current.
SiC UV Detectors under Heavy Ions Irradiation
Authors: Kalinina Evgenia V. , Lebedev Alexander A. , Berenguier Baptiste , Ottaviani Laurent , Skuratov Vladimir A.
Published: July 2015

4H-SiC ultraviolet photodetectors based on Schottky barriers have been formed on lightly doped n-type epitaxial layers grown by chemical vapor deposition method on industrial substrates. The diode structures were irradiated at 25°C with 167 MeV Xe ions at a fluence of 6x109 cm-2. Comparative studies of the optical and electrical properties of initial and irradiated structures with Schottky barriers were carried out in temperature range 23-180°C. Swift heavy ion stimulated changes in photosensitivity and electrical characteristics of the initial and irradiated detectors are explained in terms of the fluctuation traps model with the subsequent thermal dissociation.
ECL-Based SiC Logic Circuits for Extreme Temperatures
Authors: Lanni Luigia , Malm B. Gunnar , Östling Mikael , Zetterling Carl Mikael
Published: July 2015

Integrated digital circuits, fabricated in a bipolar SiC technology, have been successfully tested up to 600 °C. Operated with-15 V supply voltage from 27 up to 600 °C OR-NOR gates exhibit stable noise margins of about 1 or 1.5 V depending on the gate design, and increasing delay-power consumption product in the range 100 - 200 nJ. In the same temperature range an oscillation frequency of about 1 MHz is also reported for an 11-stage ring oscillator.
Pressureless Ag Thin-Film Die-Attach for SiC Devices
Authors: Oh Chulmin , Nagao Shijo , Sugahara Tohru , Suganuma Katsuaki
Published: July 2015

The electronic packaging has developed in the changing trend from soldering to solderless technology bonding to achieve higher performance of devices. Moreover, power electronic devices have searching for an alternative interconnection technology to replace the high temperature solder with high Pb contents, particularly suitable for next-generation wide band-gap (WBG) semiconductors such as SiC or GaN. In this study, our pressureless Ag thin-film die-attach gives an opportunity to produce the mass production by realizing low-temperature process. We demonstrate the pressureless Ag thin-film die-attach with Si and SiC to explain the mechanisms underlying the bonding process. The variation of the substrate material modifies the thermal expansion mismatch between sputtered Ag film and the substrate, and changes the bonding property, in particular die-shear strength. We reveal that the thermal stress generated by heating plays one of key roles to control the pressureless Ag thin-film die-attach process.
Electrical Properties of Hydrogen Intercalated Epitaxial Graphene/SiC Interface Investigated by Nanoscale Current Mapping
Authors: Giannazzo Filippo , Hertel Stefan , Albert Andreas , Fisichella Gabriele , La Magna Antonino , Roccaforte Fabrizio , Krieger M. , Weber Heiko B.
Published: July 2015

The electrical properties of the interface between quasi free standing bilayer graphene (QFBLG) and SiC(0001) have been investigated by nanoscale resolution current measurements using conductive atomic force microscopy (CAFM). I-V analyses were carried out on Au-capped QFBLG contacts with different sizes (from 200 down to 0.5 μm) fabricated on SiC samples with different miscut angles (from on-axis to 3.5° off-axis). The extracted QFBLG/SiC Schottky barrier height (SBH) was found to depend on the contact size. SBH values ∼0.9-1 eV were obtained for large contacts, whereas a gradual increase was observed below a critical (micrometer scale) contact size (depending on the SiC miscut angle) up to values approaching ∼1.5 eV. Nanoscale resolution current mapping on bare QFLBG contacts revealed that SiC step edges and facets represent preferential current paths causing the effective SBH lowering for larger contacts. The reduced barrier height in these regions can be explained in terms of a reduced doping of QFBLG from SiC substrate at (11-20) step edges with respect to the p-type doping on the (0001) terraces.
Structure Ordering in Mg-Zn Ferrite Nanopowders Obtained by the Method of Sol-Gel Autocombustion
Authors: Kopayev A.V. , Mokljak V.V. , Gasyuk I.M. , Yaremiy I.P. , Kozub V.V.
Published: July 2015

The Mg1-xZnxFe2O4 (x = 0, 0.2, 0.44, 0.5, 0.6) ferrite nanopowders of the spinel structure obtained by the sol-gel autocombustion (SGA) have been investigated using the X-ray diffraction and Mössbauer methods. The proofs were revealed verifying the potential occurrence of structural heterogeneity as solid solutions of various compositions of ferrites can be observed in a single phase system. In case of magnesium–zinc replacement, structural components occur, having different distribution of ferrum cations in crystallographic positions of the spinel lattice. The abnormal strength of nuclear effective fields is the indicator thereof. In addition, paramagnetic and superparamagnetic components were discovered there as well. This effect cannot be observed in the ferrite synthesis by the ceramic method.
Investigations of Non-Linear Absorption of Q-Switching Saturable Absorbers and Determination of their Main Parameters
Authors: Mlynczak Jaroslaw , Kopczynski Krzysztof , Belghachem Nabil
Published: July 2015

Investigations of non-linear absorption of q-switching absorbers were carried out. Three types of saturable absorbers were examined (Cr4+:YAG at the wavelength of 1064 nm, V3+:YAG and Co2+:YAG at the wavelength of 1332 nm) and their principal parameters were estimated. To appropriately determine these parameters 48 samples of Cr4+:YAG, 42 samples of V3+:YAG and 26 samples of Co2+:YAG were investigated making the results more reliable. Three different models of analysis of saturation effect were described and the best one chosen. Using the best model for the analysis the main parameters of the saturable absorbers were determined. On the basis of so many samples the standard deviation of the ground state absorption cross section, the excited state absorption cross section and the unsaturable losses were calculated showing how the value of these parameters may differ even for the same type of crystal.
Positron Annihilation in IR Transmitting GeS2-Ga2S3 Glasses
Authors: Klym Halyna , Ingram A. , Shpotyuk O. , Szatanik R. , Petracovschi E. , Calvez L. , Lin C.
Published: July 2015

Positron annihilation lifetime spectroscopy combined with Doppler broadening of annihilation radiation was applied to study free-volume entities in GeS2-Ga2S3glasses affected by Ga additions. It is shown that Ga-related void sub-system plays a decisive role in positron trapping process, while the overall density variation is defined mainly by Ge-related sub-system. These results serve as basis for new characterization route for inner free-volume structure of these glasses.
Coloring Changes of Congruent LiNbO3 Crystals under Redox Annealing
Authors: Sugak Dmytro Yu.
Published: July 2015

The paper is to discuss the main characteristics of the influence of high temperature annealing in different gas environments on the optical and structural properties of congruent lithium niobate crystals.