bluuebunny/crossref_metadata_2025 huggingface dataset:
1950°C Annealing of Al+ Implanted 4H-SiC: Sheet Resistance Dependence on the Annealing Time
Authors: Nipoti Roberta , Parisini Antonella , Vantaggio Salvatore , Alfieri Giovanni , Carnera Alberto , Centurioni Emanuele , Elmi Ivan , Grossner Ulrike
Published: May 2016

This study shows that, after annealing at 1950°C, a 1×1020 cm-3 Al+ implanted 4H-SiC material shows a decreasing resistivity with increasing annealing time in the range 5-25 min. After this, the resistivity remains constant up to an annealing time of 40 min. The estimated minimum time to gain the thermal equilibrium in this implanted material at 1950°C is 12 min. Electrical characterization has been performed in the 20-680 K temperature range.
Al Doping from Laser Irradiated Al Film Deposited on 4H-SiC
Authors: Ikeda Akihiro , Sumina Rikuho , Ikenoue Hiroshi , Asano Tanemasa
Published: May 2016

Al doping of 4H-SiC with high surface concentration and deep depth profile is found to be realized by irradiating single-pulse excimer laser to an Al film deposited on the surface. Optical emission spectra suggest that high-temperature molten Al is produced behind the laser-generated high-density Al plasma and Al is diffused from the molten Al into 4H-SiC. The Al doping depth reaches to ~200 nm by irradiating a single laser pulse. A pn junction diode fabricated by the doping with the molten Al shows on/off ratio over 10 orders of magnitude.
Silicon Carbide Recrystallization Mechanism by Non-Equilibrium Melting Laser Anneal
Authors: Mazzamuto Fulvio , Halty Sebastien , Mori Yoshihiro
Published: May 2016

We have demonstrated the possibility for epitaxial regrowth of crystalline SiC by laser melt annealing. The quality of the recrystallization is analyzed by XTEM, EELS, electron diffraction and XRD. The annealing guarantees a uniform activation achieved both in melting and solid phase. Carbon graphitization on the top surface and a crystallized silicon layer below is observed as an effect of the high temperature and the melting phase.
Ohmic Contact for Silicon Carbide by Carbon Nanotubes
Authors: Inaba Masafumi , Suzuki Kazuma , Hirano Yu , Norimatsu Wataru , Kusunoki Michiko , Kawarada Hiroshi
Published: May 2016

The electrical contact properties of silicon carbide (SiC) and carbon nanotubes (CNTs) were measured by conductive atomic force microscopy (C-AFM). A CNT forest was synthesized by SiC surface decomposition. Trenches, which electrically separate the conduction area, were fabricated using a focused ion beam (FIB) without a cover layer, and the resistance of each island was measured by C-AFM. From the dependence of the resistance on the CNT forest island size, the contact resistance between the CNTs and the SiC substrate was measured. By varying the dopant density in the SiC substrate, the Schottky barrier height was evaluated to be ~0.5 eV. This is slightly higher than a previously reported result obtained from a similar setup with a metal covering the CNT forest. We assumed that the damaged region existed in the islands, which is due to the trench formation by the FIB. The commensurate barrier height was obtained with the length of the damaged region assumed to be ~3 μm. Here, we could estimate the resistivity of a CNT/SiC interface without a cover layer. This indicates that a CNT forest on SiC is useful as a brief contact electrode.
Impact of NO Annealing on Flatband Voltage Instability due to Charge Trapping in SiС MOS Devices
Authors: Katsu Yoshihito , Hosoi Takuji , Nanen Yuichiro , Kimoto Tsunenobu , Shimura Takayoshi , Watanabe Heiji
Published: May 2016

We evaluated the effect of NO annealing on hole trapping characteristic of SiC metal-oxide-semiconductor (MOS) capacitor by measuring flatband voltage (VFB) shifts during a constant negative gate voltage stress under UV illumination. Under low stress voltages, the VFB shift due to hole trapping was found to be suppressed by NO annealing. However, the VFB shift of the NO-annealed device increases significantly with stress time under high stress voltage conditions, while the device without NO annealing showed only a slight shift. This result implies that NO annealing enhances generation of hole traps, leading to the degradation of SiC-MOS devices in long-term reliability.
Impact of Al Doping Concentration at Channel Region on Mobility and Threshold Voltage Instability in 4H-SiC Trench N-MOSFETs
Authors: Kutsuki Katsuhiro , Kawaji Sachiko , Watanabe Yukihiko , Tsujimura Masatoshi , Onishi Toru , Fujiwara Hirokazu , Yamamoto Kensaku , Kanemura Takashi
Published: May 2016

The effect of Al doping concentration (NA) at channel regions ranging from 1.0×1017 to 4.0×1017 cm-3 on the effective channel mobility of electron (μeff) and the threshold voltage (Vth) instability under the positive bias-temperature-stress conditions has been investigated througu the use of trench-gate 4H-SiC MOSFETs with m-face (1-100) channel regions. It was found that μeff degraded with an increase in NA. On the other hand, the increase of NA enlarged the Vth instability. These results indicate that NA has a large impact not only on the Vth value but also on the channel resistance and reliability in 4H-SiC trench MOSFETs.
Systematic Investigation of 4H-SiC Trench Properties Dependence on Channel Concentration, Crystallographic Plane, and MOS Interface Treatment
Authors: Kitai Hidenori , Hatayama Tomoaki , Tamaso Hideto , Kyogoku Shinaya , Masuda Takeyoshi , Shiomi Hiromu , Harada Shinsuke , Fukuda Kenji
Published: May 2016

We have systematically investigated the trench properties of 4H-SiC for p-type channel doping level formed by epitaxial growth, crystallographic plane, and MOS interface treatment. Our results show that the channel mobilities on the (1-100), (11-20), (-1100), and (-1-120) planes gradually decreased in the range from 1 × 1016 to 1 × 1017 cm-3 as the epitaxial channel concentration increased. An inevitable tradeoff existed between channel mobility (field-effect mobility, µFE) and threshold voltage (Vth) in trench MOSFETs. Furthermore, the maximum µFE at a channel concentration of 1 × 1017 cm-3 was 95 cm2·V-1·s-1 on the (11-20) plane with wet + hydrogen (H2) annealing, 83 cm2·V-1·s-1 on the (1-100) plane with wet + H2 annealing and 57 cm2·V-1·s-1 on the (1-100) plane with nitric oxide annealing.
Effect of Solution Drift on Crystalline Morphology in the Solution Growth of Off-Axis 4H-SiC Crystals
Authors: Kato Takashi , Kusunoki Kazuhiko , Seki Kazuaki , Okada Nobuhiro , Kamei Kazuhito
Published: May 2016

We investigated the effect of the solution flow on crystalline morphology in the off-axis 4H-SiC solution growth. In particular, we focused on the relation between the Si solution flow and step flow directions. In step parallel flow in which the solution drifted transversely to the step flow direction of the off-axis substrate, it was possible to attain a better surface morphology than in the flow in which the solution drifted toward the other direction. Furthermore, it was found that the surface morphology was found to be improved as the solution flow velocity increased. These improvements in the morphological stability are presumed to be caused by aligning the solute concentration fluctuation along the steps.
X-Ray Irradiation on 4H-SiC MOS Capacitors Processed under Different Annealing Conditions
Authors: Vivona Marilena , Fiorenza Patrick , Di Franco Salvatore , Marcandella Claude , Gaillardin Marc , Girard Sylvain , Roccaforte Fabrizio
Published: May 2016

The overall radiation response to X-ray exposure of metal-oxide-semiconductor (MOS) capacitors, subjected to two different post-deposition-annealing (PDA) processes in N2O or POCl3 atmospheres, was investigated by capacitance-voltage (C-V) analyses. The production rate and saturation density of electrically active defects, different for the two oxides, demonstrated an additional contribution to the defects formation coming from the annealing treatements. The higher susceptibility of the POCl3-annealed oxide respect to the N2O annealed is discussed.
Improved Channel Mobility by Oxide Nitridation for N-Channel MOSFET on 3C-SiC(100)/Si
Authors: Li Fan , Sharma Yogesh K. , Jennings Michael R. , Pérez-Tomás A. , Shah Vishal A. , Rong Hua , Russell Stephen , Martin David M. , Mawby Philip  Andrew
Published: May 2016

In this work we studied the gate oxidation temperature and nitridation influences on the resultant 3C-SiC MOSFET forward characteristics. Conventional long channel lateral MOSFETs were fabricated on 3C-SiC(100) epilayers grown on Si substrates using five different oxidation process. Both room temperature and high temperature (up to 500K) forward IV performance were characterised, and channel mobility as high as 90cm2/V.s was obtained for devices with nitrided gate oxide, considerable higher than the ones without nitridation process (~70 cm2/V.s).
Alkali Metal Re-Distribution after Oxidation of 4H-SiC
Authors: Linnarsson Margareta K. , Suvanam Sethu Saveda , Vines Lasse , Hallén Anders
Published: May 2016

Relocation of alkali metals sodium, potassium and cesium during oxidation of 4H-SiC has been studied by secondary ion mass spectrometry. The alkali metal source has been introduced by ion implantation before oxidation into n-and p-type 4H-SiC samples. Dry oxidation of SiC has been performed at 1150 oC during 4, 8 and 16 h. In the formed oxide, the main part of the alkali metals diffuses out via the SiO2 surface. Close to the moving SiO2/SiC interface, a minor amount of alkali metals is retained. In the SiC material, the main amount of implanted alkali atoms is not redistributed during the oxidation, although a minor amount diffuses deeper into the samples. For p-type 4H-SiC, the diffusion deeper into the samples of the studied alkali metals decreases as the mass increases, Na+<K+<Cs+, but the sodium mobility is substantial already at 1150 °C.
Investigation of Interface State Density with Varied SiO2 Thickness in La2O3/SiO2/4H-SiC MOS Capacitors
Authors: Wang Yu Cheng , Zhang Yu Ming , Jia Ren Xu
Published: May 2016

SiO2 with varying thickness (0, 4.45, and 8.05 nm) were grown on n type 4H-SiC epilayer by thermal oxidation and La2O3 were stacked on them using atomic layer deposition (ALD). The La2O3/SiO2/4H-SiC metal-oxide-semiconductor (MOS) capacitors were analyzed by X-ray photoelectron spectroscopy (XPS) and capacitance-voltage (C-V) measurements. C-V curves show that introducing an ultrathin SiO2 can reduce the effect of lattice mismatch of La2O3/4H-SiC structure and then improve interface property. However, the interface quality is reduced as SiO2 was grown thicker. XPS data show that more carbon cluster remains at the interfacial between SiO2 and 4H-SiC as the oxidation time increases.
Passivation and Generation of States at P-Implanted Thermally Grown and Deposited N-Type 4H-SiC/SiO2 Interfaces
Authors: Sledziewski Tomasz , Weber Heiko B. , Krieger M.
Published: May 2016

In this work the effect of phosphorus on the electrical properties of n-type 4H-SiC MOS capacitors is studied. Phosphorus ions are implanted into the epitaxial layers prior to the deposition of SiO2 by PECVD, in shallow depths and at concentrations at the oxide-semiconductor interface in the range of (5 x 1017…1 x 1019) cm-3. Those samples are compared with 31P-implanted 4H-SiC MOS capacitors with thermally grown oxides, which were primarily investigated in the previous work of the authors. It is shown that independently of the oxide technology phosphorus may lead to decrease of the density of interface traps, whose response time to the AC voltage is longer than 1 µs. The side-effect of the implantation of phosphorus is generation of the very fast interface states, which are able to follow the frequencies over 1 MHz.
Conduction Mechanisms at SiO2/4H-SiC Interfaces in MOS-Based Devices Subjected to Post Deposition Annealing in N2O
Authors: Fiorenza Patrick , Giannazzo Filippo , Frazzetto Alessia M. , Guarnera Alfio , Saggio Mario , Roccaforte Fabrizio
Published: May 2016

This paper reports on the conduction mechanisms through the gate oxide and trapping effects at SiO2/4H-SiC interfaces in MOS-based devices subjected to post deposition annealing in N2O. The phenomena were studied by temperature dependent current–voltage measurements. The analysis of both n and p-MOS capacitors and of n-channel MOSFETs operating in the “gate-controlled-diode” configuration revealed an anomalous hole conduction behaviour through the SiO2/4H-SiC interface, with the onset of current conduction moving towards more negative values during subsequent voltage sweeps. The observed gate current instabilities upon subsequent voltage sweeps were deeply investigated by temperature dependent cyclic gate current measurements. The results were explained by the charge-discharge mechanism of hole traps in the oxide.
Evolution of Threading Edge Dislocations at Earlier Stages of PVT Growth for 4H-SiC Single Crystals
Authors: Tani Komomo , Fujimoto Tatsuo , Kamei Kazuhito , Kusunoki Kazuhiko , Seki Kazuaki , Yano Takayuki
Published: May 2016

Dislocation structures at the seed/grown-crystal interface in PVT-grown 4H-SiC crystals are investigated. The dislocation density is found to show a sharp increase at the interface and its main contribution is probably ascribable to TEDs which stem from BPDs generating at the interface through the structural transformation. Intense TEM observations reveal an intriguing in-plane distribution structure of the interface BPDs; the BPDs form a two-dimensional dislocation network comprising of {-1100} partial dislocations associated with expanded areas of stacking faults at the nodes of the network.
Study of 4H-SiC Junction Barrier Schottky(JBS) Diode Using Various Junction Structures
Authors: Kim Ki Hyun , Kang Ye Hwan , Lee Jung Hun , Jung Eun Sik , Kang In Ho , Yang Chang Heon
Published: May 2016

In this paper, to verify implant effect characteristics variation by stripe type, grid type and circle type, the P+ implant patterning was studied. The result of two-dimensional simulation was controlled by adjusting the relative area of Schottky and p–n junction dimensions of the device, which is easily implemented during the device layout design. 4H-SiC JBSs with three types have been successfully fabricated and breakdown voltage in the range of 1694–2051 V has been achieved. The results of fabricated JBSs, show that the stripe type JBSs combine the best features of the P+ implant patterns.
Modeling of Inhomogeneous 4H-SiC Schottky and JBS Diodes in a Wide Temperature Range
Authors: Asllani Besar , Berthou Maxime , Tournier Dominique , Brosselard Pierre , Godignon Philippe
Published: May 2016

This paper presents a study of the Schottky barrier evolution on SBD and JBS diodes over a wide range of temperatures from 80 to 500 K. We show that inhomogeneities of the Schottky contact have a strong impact on the dependence of barrier characteristics with temperature, especially below 200 K. Analysis of the reverse bias current of such diodes at low temperature show that the barrier height depends on temperature but also on voltage.
Optimum Design of 4H-SiC Junction Barrier Schottky Diode with Consideration of the Anisotropic Impact Ionization
Authors: Jiang Hua Ping , Ke Mao Long , Sharma Yogesh K. , Dai Xiao Ping , Deviny Ian , Zheng Chang Wei
Published: May 2016

Optimum n-drift region of a 4H-SiC Junction Barrier Schottky Diode (JBS) was analyzed by simulation with consideration of the anisotropic impact ionization. According to the detailed simulations using SRIM and Sentaurus, model parameters of empirical equations were obtained through fitting, which showed that the anisotropic avalanche model (2D-ANISO) differs significantly from the 1-dimensional empirical model (1D-Cooper) and the old isotropic avalanche model (2D-ISO). These initial results suggested that the JFET resistance and anisotropic impact ionization should be taken into account during the optimization of a 4H-SiC JBS in which field crowding at the corner of p-grid causes higher reverse leakage current.
Epitaxial Layer Thickness Dependence on Heavy Ion Induced Charge Collection in 4H-SiC Schottky Barrier Diodes
Authors: Makino Takahiro , Onoda Shinobu , Hoshino Norihiro , Tsuchida Hidekazu , Ohshima Takeshi
Published: May 2016

The charge enhancement in SiC-Schottky Barrier Didoes (SBDs) with different epi-layer thicknesses under the condition of the single-species ion irradiation was simulated to find out the mechanism of heavy-ion-induced anomalous charge collection in SiC-SBDs. The value of ion induced charge depended on the thickness of epitaxial-layer in the SBDs. The simulation result suggests that the impact ionization is one of the key effects to lead ion induced charge enhancement.
Comparison of 2.5D and 3D Simulation Methods for Limiting Electrode Debiasing of 4H-SiC Interdigitated Devices
Authors: Thierry-Jebali Nicolas , Kempf Thibault , Mandorlo Fabien
Published: May 2016

This paper assesses the 2.5D simulation method for limiting the electrodes debiasing of interdigitated devices. This method uses both spice and finite element method simulations where a resistance grid models the electrodes and a 2D finite elements structure models the device. A lateral 4H-SiC PiN diode has been selected for this study. In order to assess this method, 2.5D simulation method has been compared to 3D simulations.
Low Resistivity SiC Devices with a Drift Layer Optimized by Variational Approach
Authors: Tominaga Takaaki , Kawabata Naoyuki , Koyama Akihiro , Tanaka Takanori , Watanabe Hiroshi , Tomita Nobuyuki , Miura Naruhisa , Kuroiwa Takeharu , Yamakawa Satoshi
Published: May 2016

A reduction of drift resistivity by an optimized epitaxial layer has been theoretically calculated using variational approach. An epitaxial growth was carried out based on the calculated design of the drift layer for a 1.7 kV SBD, with a conventional epitaxial growth for comparison, to experimentally prove a reduction of drift resistivity. An improvement of trade-off relationships for the SBD with an optimized epitaxial layer has been revealed through the investigation of their electrical characteristics.
A New Type of Single Carrier Conduction Rectifier on SiC
Authors: Tanimoto Satoshi , Ueoka Kenichi , Fujita Takaya , Araki Sawa , Kojima Kazu , Makino Toshiharu , Yamasaki Satoshi
Published: May 2016

A new rectifier, called SPND or SNPD (Schottky-PN or -NP junction diode) and inherently showing low on-resistance and unipolar operation, was experimentally demonstrated for the first time on 4H-SiC. It is structured with an n– or a p– region of very low doping that is sandwiched and completely depleted between a Schottky junction and a one-sided PN junction. Either electrons or holes, but not both, contribute to the current conduction process. Clear and sharp rectifying properties are observed over the entire range of applied voltage.
Growth of Low Resistivity p-Type 4H-SiC Crystals by Sublimation with Using Aluminum and Nitrogen Co-Doping
Authors: Eto Kazuma , Suo Hiromasa , Kato Tomohisa , Okumura Hajime
Published: May 2016

Low resistivity p-type SiC bulk crystals were grown by the sublimation method with using aluminum and nitrogen co-doping. In the sublimation growth of 4H-SiC, to obtain low-resistive p-type crystals are not easy because of the instability of 4H-SiC polytype with highly Al-doping. We have grown < 90 mΩcm p-type 4H-SiC bulk crystals with the co-doping condition. The results of SIMS and Raman spectroscopy show that high concentration of nitrogen co-doping could be effective to the stabilization of 4H polytype with p-type SiC growth.
Optimization of 1700V 4H-SiC JBS Diode Parameters
Authors: Sharma Rupendra Kumar , Hazdra Pavel , Popelka Stanislav , Mihaila Andrei , Bartolf Holger
Published: May 2016

The in-depth design optimization of the active layer of the 1700V class 4H-SiC JBS/MPS diode structure is discussed. The important design parameters such as junction depth (d), width (w) of p+ areas, and spacing (s) between them were optimized for the best possible trade-off between the unipolar ON-state voltage drop, the OFF-state breakdown voltage, and the bipolar surge current capability. The optimization was performed using a state-of-the-art simulator using device models calibrated on a commercially available JBS rectifier. The results show that the spacing s between the p+ regions is the most decisive parameter which has to be properly designed according to the required voltage class. For the 1700 V voltage class, s should be between 2 to 4 μm and the s/w ratio should be kept low. The depth d of the p+ pattern has a pronounced impact on the ignition of bipolar action such that with decreasing d the surge current capability decreases significantly.
Experimental Investigation of the Seeding Stage during SiC Solution Growth Using Si and Al-Si Solvents
Authors: Shin Yun Ji , Ariyawong Kanaparin , Doisneau Beatrice , Dedulle Jean Marc , Brosselard Pierre , Chaussende Didier
Published: May 2016

In this work, we have investigated the seeding stage of 4H-SiC top seeded solution growth through the systematic observation of surface morphologies and numerical simulation. Different growth temperatures, C- and Si-polarities, and different solvents have been studied. This is the first report of transient nucleation of parasitic 3C-SiC at the early stage of solution growth in pure Si solvent even at high temperature. This unusual phenomenon was attributed to a huge temperature difference between the seed crystal and solvent surface at the seeding stage. We demonstrated that preheating of the seed crystals or addition of Al were effective to prevent such parasitic 3C-SiC nucleation.
Comparison of Test Methods for Proper Characterization of VT in SiC MOSFETs
Authors: Habersat Daniel B. , Lelis Aivars J. , Green Ronald , El Mooro
Published: May 2016

A survey of methods for characterizing threshold voltage (VT) drift when applied to commercial SiC DMOSFETs was conducted to explore how results can vary from one test to another. Typical linear-with-log-stress-time VT drift was observed with a rate of increase near 50–60 mV/dec for all methods. However, the magnitude of the drift varied greatly depending on the time delay between stress and measurement. A power law recovery ( ) common to all methods results in much smaller VT drifts when using slower methods, meaning long delays between stress and measurement can lead to tests that are unable to adequately discriminate bad devices from good.
Influence of Impurities in SiC Powder on High Quality SiC Crystal Growth
Authors: Heo S. , Son H.R. , Kim Byung Sook , Kim M.S. , Han J.E. , Lee Dong Hoon , Min K.S. , Kim S.I. , Ha S. , Shin Dong Geun
Published: May 2016

SiC powders having different purities were prepared by carbothermal reduction under different conditions from traditional process and SiC single crystals were grown by the PVT method from the powders. After crystal growth, boule was cut to wafers and they were polished for chemical and defect analyses. Total impurities including Al, B and Ti which were derived from powders decreased remarkably during crystal growth. The formation of defects including micropipe and dislocations such as TED, TSD and BPD was strongly influenced by impurity content. The effect of impurity seemed to be negligible at below 1ppm level for MPD. On the other hand, dislocations continuously decreased even more when higher purity SiC powder below 1ppm level was used.
Change in Characteristics of SiC MOSFETs by Gamma-Ray Irradiation at High Temperature
Authors: Matsuda Takuma , Yokoseki Takashi , Mitomo Satoshi , Murata Koichi , Makino Takahiro , Abe Hiroshi , Takeyama Akinori , Onoda Shinobu , Tanaka Yuki , Kandori Mikio , Yoshie Toru , Hijikata Yasuto , Ohshima Takeshi
Published: May 2016

Radiation response of 4H-SiC vertical power Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs) was investigated at 150°C up to 10.4 MGy. Until irradiation at 1.2 MGy, the drain current – gate voltage curves of the SiC MOSFETs shifted to the negative voltage side, and the leakage of drain current at gate voltages below threshold voltage increased with increasing absorbed dose. However, no significant change in the electrical characteristics of SiC MOSFETs was observed at doses above 1.2 MGy. For blocking characteristics, there were no degradations of the SiC MOSFETs irradiated at 150°C even after irradiated at 10.4 MGy.
Processing and Prolonged 500 °C Testing of 4H-SiC JFET Integrated Circuits with Two Levels of Metal Interconnect
Authors: Spry David J. , Neudeck Philip G. , Chen Liang Yu , Lukco Dorothy , Chang Carl W. , Beheim Glenn M. , Krasowski Michael J. , Prokop Norman F.
Published: May 2016

Complex integrated circuit (IC) chips rely on more than one level of interconnect metallization for routing of electrical power and signals. This work reports the processing and testing of 4H-SiC junction field effect transistor (JFET) prototype IC’s with two levels of metal interconnect capable of prolonged operation at 500 °C. Packaged functional circuits including 3- and 11-stage ring oscillators, a 4-bit digital to analog converter, and a 4-bit address decoder and random access memory cell have been demonstrated at 500 °C. A 3-stage oscillator functioned for over 3000 hours at 500 °C in air ambient. Improved reproducibility remains to be accomplished.
Modelling of 4H-SiC VJFETs with Self-Aligned Contacts
Authors: Zekentes Konstantinos , Vassilevski Konstantin , Stavrinidis Antonis , Konstantinidis George , Kayambaki Maria , Vamvoukakis Konstantinos , Vassakis Emmanouil , Peyre Hervé , Makris Nikolaos , Bucher Matthias , Schmid Patrick , Stefanakis Dionyssios , Tassis Dimitrios
Published: May 2016

Purely vertical 4H-SiC JFETs have been modeled by using three different approaches: the analytical model, the finite element model and the compact model. The results of the modeling have been compared with experimental results on a series of fabricated self-aligned devices with two different channel lengths (0.3 and 1.1μm) and various channel widths (1.5, 2, 2.5, 3, 4 and 5 μm). For all the considered models I-V and C-V characteristics could be satisfactorily simulated.
Comparison of Energy Losses in High-Current 1700 V Switches
Authors: Sundaresan Siddarth G. , Grummel Brian , Singh Ranbir
Published: May 2016

1700 V/20 mΩ SiC Junction Transistors (SJTs) were recently released by GeneSiC with specific on-resistance as low as 2.3 mΩ-cm2, and current gain > 100. This paper benchmarks the electrical characteristics of the 1700 V SJTs against two best-in-class Si IGBTs. The SJT features 47% and 49% lower on-state voltage drops than the two Si IGBTs, respectively, with the SJT operating at 175°C, and the IGBTs at 150°C. The conduction power loss of the best Si IGBT is 2.2 times larger than the SJT at 25°C, and 1.6 times larger at 150°C. The leakage currents measured on the best IGBT at 1700 V and 150°C is 0.93 mA, as compared to 200 nA for the SJT at 175°C. As compared to the SJT, 3.6x and 3.3x higher (hard) switching energy losses are measured on the best 1700 V Si IGBT, at 25°C, and 150°C, respectively, when switching at a DC link voltage of 1200 V.
6.5 kV n-Channel 4H-SiC IGBT with Low Switching Loss Achieved by Extremely Thin Drift Layer
Authors: Watanabe Naoki , Yoshimoto Hiroyuki , Shima Akio , Yamada Renichi , Shimamoto Yasuhiro
Published: May 2016

Thin drift layers were used to realize n-channel 4H-SiC IGBTs with an extremely low switching loss. The thickness of a drift layer was 60 μm, which was designed for a blocking voltage of 6.5 kV. An on-voltage of 5.4 V was obtained at a collector current of 100 A/cm2 and the specific differential on-resistance at 100 A/cm2 was 20 mΩcm2 at room temperature, indicating proper bipolar operation. A switching evaluation of the SiC IGBTs was performed with a bus voltage of 3.6 kV and a load current of 10 A, and a turn-off loss of 1.2 mJ was obtained. This turn-off loss is very small compared to the values in the current literatures, and was estimated to be an over 80% reduction. The series operation of thin-drift-layer 6.5 kV SiC IGBTs can ensure a lower switching loss than the single operation of higher blocking voltage devices in power conversion systems.
Improved Simulation Models for Designing Novel Edge Termination and Current Spreading Layers for 3300-V-Class 4H-SiC Implantation–Epitaxial MOSFETs with Low On-Resistance and Robustness
Authors: Shiomi Hiromu , Tsuji Takashi , Ohse Naoyuki , Onishi Yasuhiko , Fukuda Kenji
Published: May 2016

Impact ionization coefficients are important material properties that determine the breakdown voltage and safe operating area of power devices. This paper presents an anisotropy breakdown model with modified parameters that reproduces well experimental results for both peak breakdown voltages and sharp drops in breakdown voltage at high junction–termination–extension (JTE) acceptor concentrations. Using a newly developed simulation model, we optimized the edge termination and current-spreading layers (CSLs) and obtained a low specific on-resistance (RONA) of 11.6 mΩcm2 for a breakdown voltage (BVDSS) of approximately 4 kV and a high-avalanche-withstanding energy robustness of 4.6 Jcm-2.
Structural Transformation from TSDs to Frank-Type Stacking Faults by Giant Bunched Steps in PVT-Grown 4H-SiC Single Crystals
Authors: Sato Shinya , Fujimoto Tatsuo , Tsuge Hiroshi , Katsuno Masakazu , Nakabayashi Masashi , Ushio Shoji , Tani Komomo , Yano Takayuki
Published: May 2016

Structural transformation from threading screw dislocations (TSDs) to stacking faults (SFs) has been investigated for PVT-grown 4H-SiC single crystals using X-ray topography and transmission electron microscopy (TEM). The transformation of TSDs is induced by the structural interference with bunched surface macrosteps over 100 nm in height. The stacking sequence of a SF was determined to be (433) in Zadanov's notation by using high-resolution TEM. Our detailed analyses revealed that the (433) stacking structure can be constructed by a combination of five faults including both four Frank type faults and one Shockley type fault.
High Performance of 5.7kV 4H-SiC JBSs with Optimized Non-Uniform Field Limiting Rings Termination
Authors: Yuan Hao , Song Qing Wen , Tang Xiao Yan , Zhang Yu Ming , Guo Hui , Wang Yue Hu , Zhang Yi Meng , Jia Ren Xu , Zhang Yi Men
Published: May 2016

In this paper, a 5.7kV 4H-SiC Junction Barrier Schottky diode(JBS) with non-uniform field limiting rings termination is simulated and fabricated successfully based on a epitaxial thickness of 49μm and the doping concentration about 1.04×1015cm-3 respectively. The reverse breakdown voltage could reach to 5.7kV at least at reverse current of 200μA. And the on-state voltage is 3V at the forward current of 2A, corresponding to an on-resistance of 32mΩ•cm2. The corresponding figure-of- merit of VB2/ RSP-ON for our fabricated device is 1.026 GW/cm2, which is closing to the optimal levels among several reported SiC JBS.
Exploring the Gas Sensing Performance of Catalytic Metal/Metal Oxide 4H-SiC Field Effect Transistors
Authors: Puglisi Donatella , Eriksson Jens , Andersson Mike , Huotari Joni , Bastuck Manuel , Bur Christian , Lappalainen Jyrki , Schuetze Andreas , Lloyd Spetz Anita
Published: May 2016

Gas sensitive metal/metal-oxide field effect transistors based on silicon carbide were used to study the sensor response to benzene (C6H6) at the low parts per billion (ppb) concentration range. A combination of iridium and tungsten trioxide was used to develop the sensing layer. High sensitivity to 10 ppb C6H6 was demonstrated during several repeated measurements at a constant temperature from 180 to 300 °C. The sensor performance were studied also as a function of the electrical operating point of the device, i.e., linear, onset of saturation, and saturation mode. Measurements performed in saturation mode gave a sensor response up to 52 % higher than those performed in linear mode.
Characteristics and Regeneration Properties of Manganese Oxide Sorbent under O2 Atmosphere
Authors: Liu Li Ping , Ju Shang Guan , Wang Hui Qing , Zhao Xiao Wei , Mi Jie
Published: May 2016

The regeneration behavior of manganese oxide sorbent under O2atmosphere was investigated in a fixed bed micro-reactor under the influence of different temperatures and O2 concentrations. The change in phase of the sulﬁded and the regenerated sorbents was analyzed by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) techniques. MnS, Mn3O4 and MnSO4 were found in regenerated sorbent at 400 °C, which indicated that the regeneration of the sulﬁded sorbent was not complete, however, MnS was converted to Mn3O4, Mn2O3 and few MnSO4 at 800 °C. The manganese sulfate formed during the regeneration but decomposed to Mn2O3 at 800 °C. MnS reacts with O2 to form Mn3O4 and MnSO4, and then MnSO4 was decomposed at 800 °C. The results show that the optimum regeneration temperature and O2 concentration obtained from this experiment are 800 °C and 2.2 vol %, respectively, and the regeneration conversion ratio was about 95%.
Semiconducting Materials for Photonic Technology
Authors: Zhang Dao Hua
Published: May 2016

Semiconducting materials are important photonic materials and the technologies developed have been utilized in many fields of the modern society and they are closely related to the quality of our life. The main applications of the materials are for light source and sensing originated from interaction of photons and matters. In this invited talk, I will first present our work on the properties of the semiconducting materials and their applications as lasers and photodetectors, and then present integrated hybrid subwavelength structures which show significant enhancement on device performance. It is believed that complex hybrid structures which combine quantum-and hetero-structures made of semiconducting materials, and subwavelength structure for performance enhancement are the main focus in the near future.
Linear estimation of girth as a covariate on yield parameters of rubber (Hevea brasiliensis Muell.Arg.): correlation of girth with latex volume and weight
Authors: Karunaratne P. M. A. S. , Wijeratne A. W. , Kumara J. B. D. A. P.
Published: May 2016

Rubber, (Hevea brasiliensis Mull.Arg). plays an important role in the Sri Lankan economy as one of the main export agricultural crops in the country. Latex is the economically important part of rubber tree for which the girth increment is a very important factor to ensure higher latex yield. It is known fact that girth related to the latex yield of rubber. Therefore the current study was conducted to estimate the girth as covariate for rubber yield and to predict the correct out come of future experiments related to rubber. The relationships of latex yield and girth of rubber were estimated using a linear regression model. Three clones RRIC 100, RRIC 121 and PB 86 were used for the experiment. Latex yield was determined by latex volume of individual trees and Grams per Tree per Tapping (GTT). Each clone was categorized into 3 girth classes as poor girth (class 1,50-64 cm), medium girth (class 2, 65-79 cm) and high girth (class 3, >80 cm). The regression coefficient for RRIC 100 was +1.520 and +0.466 for GTT and latex volume respectively. The recorded regression coefficients for clone RRIC 121 were +0.690 for GTT and +1.192 for latex volume. Similarly PB 86 produced regression coefficients +0.602 for GTT and +1.582 for latex volume. The significance by positive correlation between latex yield and girth in tested clones suggested that tree girth can be taken as a covariate in rubber experiments.
Correlates of adoption of composite fish culture practices by fish farmers of Assam, India
Authors: Talukdar P. K. , Sontaki B. S.
Published: May 2016

The present study carried out during 1999 - 2000 in the purposively selected Sonitpur district of Assam focused on the factors influencing adoption of composite fish culture practices by the fish farmers. The data were gathered using a structured and pre-tested interview schedule from 60 randomly selected fish farmers. The findings revealed that majority (63%) of fish farmers belonged to medium category of adoption. The adoption behaviour of composite fish culture practices was positively influenced by the factors like extension participation, economic motivation, cosmopoliteness, scientific orientation and knowledge of fish farmers, and negatively by their age. In view of the above findings, the study recommends that efforts should be made by extension agencies through their various programmes to highlight the economic benefits of composite fish farming to promote large-scale adoption of this technology. Study tours, exposure visits, participation in fairs and exhibitions could be the ideal methods for promoting adoption of composite fish culture
CSF-1R–Dependent Lethal Hepatotoxicity When Agonistic CD40 Antibody Is Given before but Not after Chemotherapy
Authors: Byrne Katelyn T. , Leisenring Nathan H. , Bajor David L. , Vonderheide Robert H.
Published: May 2016

Cancer immunotherapies are increasingly effective in the clinic, especially immune checkpoint blockade delivered to patients who have T cell–infiltrated tumors. Agonistic CD40 mAb promotes stromal degradation and, in combination with chemotherapy, drives T cell infiltration and de novo responses against tumors, rendering resistant tumors susceptible to current immunotherapies. Partnering anti-CD40 with different treatments is an attractive approach for the next phase of cancer immunotherapies, with a number of clinical trials using anti-CD40 combinations ongoing, but the optimal therapeutic regimens with anti-CD40 are not well understood. Pancreatic ductal adenocarcinoma (PDA) is classically resistant to immunotherapy and lacks baseline T cell infiltration. In this study, we used a tumor cell line derived from a genetically engineered mouse model of PDA to investigate alterations in the sequence of anti-CD40 and chemotherapy as an approach to enhance pharmacological delivery of chemotherapy. Unexpectedly, despite our previous studies showing anti-CD40 treatment after chemotherapy is safe in both mice and patients with PDA, we report in this article that anti-CD40 administration <3 d in advance of chemotherapy is lethal in more than half of treated C57BL/6 mice. Anti-CD40 treatment 2 or 3 d before chemotherapy resulted in significantly increased populations of both activated myeloid cells and macrophages and lethal hepatotoxicity. Liver damage was fully abrogated when macrophage activation was blocked using anti–CSF-1R mAb. These studies highlight the dual nature of CD40 in activating both macrophages and T cell responses, and the need for preclinical investigation of optimal anti-CD40 treatment regimens for safe design of clinical trials.
Isolation of Madre de Dios Virus (Orthobunyavirus; Bunyaviridae), an Oropouche Virus Species Reassortant, from a Monkey in Venezuela
Authors: Navarro Juan-Carlos , Giambalvo Dileyvic , Hernandez Rosa , Auguste Albert J. , Tesh Robert B. , Weaver Scott C. , Montañez Humberto , Liria Jonathan , Lima Anderson , Travassos da Rosa Jorge Fernando Soares , da Silva Sandro P. , Vasconcelos Janaina M. , Oliveira Rodrigo , Vianez João L. S. G. , Nunes Marcio R. T.
Published: May 2016

Oropouche virus (OROV), genus Orthobunyavirus, family Bunyaviridae, is an important cause of human illness in tropical South America. Herein, we report the isolation, complete genome sequence, genetic characterization, and phylogenetic analysis of an OROV species reassortant, Madre de Dios virus (MDDV), obtained from a sick monkey (Cebus olivaceus Schomburgk) collected in a forest near Atapirire, a small rural village located in Anzoategui State, Venezuela. MDDV is one of a growing number of naturally occurring OROV species reassortants isolated in South America and was known previously only from southern Peru.
Extended Occupational Therapy Reintegration Strategies for a Woman With Guillain-Barré Syndrome: Case Report
Authors: Tomita Machiko R. , Buckner Kathryn , Saharan Sumandeep , Persons Kimberley , Liao Sheng Hui
Published: May 2016

This case report describes a unique long-term functional recovery process to promote successful community reintegration for a woman with Guillain-Barré syndrome (GBS), a rare autoimmune disease. Her main symptoms were very limited mobility and depressive symptoms due to the unknown cause of and cure for the illness. Holistic occupational strategies helped the client stabilize her emotional state, create a safe home environment, improve a communication method, increase physical activity, and promote social participation. Participation in a fall prevention clinical trial lowered her risk of falling; at 9 mo, she reached 75% of the maximum Social Integration score; at 13 mo, she reached near-normal level for activities of daily living (ADLs) and her fastest time for the Timed Up and Go test; and at 2 yr, she achieved a 100% score in instrumental ADLs. For community integration of clients with GBS, a comprehensive strategic self-management approach should be prescribed for long-term recovery.
Detection of dimming/brightening in Italy from homogenized all-sky and clear-sky surface solar radiation records and underlying causes (1959–2013)
Authors: Manara Veronica , Brunetti Michele , Celozzi Angela , Maugeri Maurizio , Sanchez-Lorenzo Arturo , Wild Martin
Published: May 2016

Abstract. A dataset of 54 daily Italian downward surface solar radiation (SSR) records has been set up collecting data for the 1959–2013 period. Particular emphasis is placed upon the quality control and the homogenization of the records in order to ensure the reliability of the resulting trends. This step has been shown as necessary due to the large differences obtained between the raw and homogenized dataset, especially during the first decades of the study period. In addition, SSR series under clear-sky conditions were obtained considering only the cloudless days from corresponding ground-based cloudiness observations. Subsequently, the records were interpolated onto a regular grid and clustered in two regions, Northern and Southern Italy, which were averaged in order to get all-sky and clear-sky regional SSR records. Their temporal evolution is presented, and possible reasons for differences between all-sky and clear-sky conditions and between the two regions are discussed in order to understand which part of the SSR variability depends on aerosols or clouds. Specifically, the all-sky SSR records show a decrease until the mid-1980s (dimming period) and a following increase until the end of the series (brightening period) even if the strength and the persistence of the tendencies are not the same in all seasons. The clear-sky records present stronger tendencies than the all-sky records during the dimming period in all seasons and during the brightening period in winter and autumn. This suggests that under all-sky the variations caused by the increase/decrease of the aerosol content have been partially masked by cloud cover variations, especially during the dimming period. Under clear-sky the observed dimming is stronger in the South than in the North. This peculiarity could be a consequence of a significant contribution of mineral dust variations to the SSR variability.
Inter-comparison of NIOSH and IMPROVE protocols for OC and EC determination: Implications for inter-protocol data conversion
Authors: Wu Cheng , Huang X. H. Hilda , Ng Wai Man , Griffith Stephen M. , Yu Jian Zhen
Published: May 2016

Abstract. Organic Carbon (OC) and Elemental Carbon (EC) are operationally defined by analytical methods. As a result, OC and EC measurements are protocol dependent, leading to uncertainties in their quantification. In this study, more than 1300 Hong Kong samples were analyzed using both NIOSH TOT and IMPROVE TOR protocols to explore the cause of EC disagreement between the two protocols. EC discrepancy mainly (83 %) arises from a difference in peak inert mode temperature, which determines the allocation of OC4NSH, while the rest (17 %) is attributed to a difference in the laser signal (transmittance vs. reflectance) applied for the charring correction. Evidence shows that the magnitude of the EC discrepancy is positively correlated with the intensity of biomass burning signal, whereby biomass burning increases the fraction of OC4NSH, and widens the disagreement in the inter-protocol EC determination. It is also found that the EC discrepancy is positively correlated with the abundance of metal oxide in the samples. Two approaches (M1 and M2) that translate NIOSH TOT OC and EC data into IMPROVE TOR OC and EC data are proposed. M1 uses direct relationship between ECNSH_TOT and ECIMP_TOR for reconstruction, M1: ECIMP_TOR = a × ECNSH_TOT + b while M2 deconstructs ECIMP_TOR into several terms based on analysis principles, and apply regression only on the unknown terms. M2: ECIMP_TOR = AECNSH  + OC4NSH − (a × PCNSH_TOR + b) where AECNSH, apparent EC by NISOH protocol, is the carbon that evolves in He/O2 analysis stage, OC4NSH is the carbon that evolves at the fourth temperature step of the He only analysis stage, and PCNSH_TOR is the pyrolyzed carbon as determined by NIOSH protocol. The implementation of M1 to all urban site data (without considering site or seasonal specificity) yields the following equation, M1 (urban data): ECIMPTOR = 2.20 × ECNSHTOT − 0.05 While both M1 and M2 are acceptable, M2 with site-specific parameters provides the best reconstruction performance. Secondary OC (SOC) estimation using OC and EC by the two protocols is compared. An analysis of the usability of reconstructed ECIMP_TOR and OCIMP_TOR suggests that the reconstructed values are not suitable for SOC estimation due to poor reconstruction of the OC/EC ratio.
Synergy between middle infrared and millimeter-wave limb sounding of atmospheric temperature and minor constituents
Authors: Cortesi Ugo , Del Bianco Samuele , Ceccherini Simone , Gai Marco , Dinelli Bianca Maria , Castelli Elisa , Oelhaf Hermann , Woiwode Wolfgang , Höpfner Michael , Gerber Daniel
Published: May 2016

Abstract. Synergistic exploitation of redundant and complementary information from independent observations of the same target remains a major issue in atmospheric remote sounding and increasing attention is devoted to investigate optimized or innovative methods for the combination of two or more measured data sets. This paper focuses on the synergy between middle infrared and millimeter-wave limb sounding measurements of atmospheric composition and temperature and reports the results of a study conducted as part of the preparatory activities of the PREMIER (Process Exploration through Measurements of Infrared and millimeter-wave Emitted Radiation) mission candidate to the Core Missions of the European Space Agency (ESA) Earth Explorer 7. The activity was based on data acquired by the MIPAS-STR (Michelson Interferometer for Passive Atmospheric Sounding – STRatospheric aircraft) and MARSCHALS (Millimetre-wave Airborne Receivers for Spectroscopic CHaracterisation in Atmospheric Limb Sounding) instruments on-board the high-altitude research aircraft M-55 Geophysica during the flight of the PremierEx (PREMIER Experiment) campaign on 10 March 2010 from Kiruna, Sweden, for observation of the Arctic upper troposphere and lower stratosphere. The cloud coverage observed along the flight provided representative test cases to evaluate the synergy in three different scenarios: low clouds in the first part, no clouds in the central part and high tropospheric clouds at the end. The calculation of synergistic profiles of four atmospheric targets (i.e., O3, HNO3, H2O and temperature) was performed using a posteriori combination of individual retrieved profiles, i.e., Level 2 (L2) data rather than simultaneous inversion of observed radiances, i.e., Level 1 (L1) data. An innovative method of data fusion, based on the Measurement Space Solution (MSS) was applied along with the standard approach of inversion of MARSCHALS spectral radiances using MIPAS-STR retrieval products as a priori information (L1 + L2 method). A quantitative estimate and cross-check of the results of MSS data fusion and (L1 + L2) method was achieved based on a specific set of quantifiers including the total retrieval error, the number of degrees of freedom, the relative information distribution and the synergy factor.