bluuebunny/crossref_metadata_2025 huggingface dataset:
Racial Diversity in Publicly Traded Companies
Authors: Thompson Jeffrey Kurt Orlando , Thompson Richard C.
Published: July 2020

This article shares some of the results of a thesis investigating the relationship between the racial diversity of the board of directors in Canadian companies that traded on the Toronto Stock Exchange (TSX). The central question addressed was how organizational factors affect the racial diversity of board membership. The thesis expanded on a prior study that modelled gender diversity on boards of directors by focusing on the recommended area of racial diversity in the Canadian environment. Though many companies do not share their diversity details, using multiple regression analysis, the results showed that there was more racial diversity on larger boards. From a population of about 3,000 companies, the researchers identified a sample of 148 companies, with all the required parameters. This sample contained 1,246 board members, where 9.4% (117 board members) were visible minorities. The ANOVA analysis of the model demonstrated that it was a suitable tool to conduct the investigation. However, the variables did not show any strong significance.
Interplays Between Methane Emission and Agricultural Output
Authors: Das Ramesh Chandra , Mukherjee Arundhati
Published: July 2020

There have been debates among the so-called developed economies and less developed and emerging economies on the issue of ‘who is responsible for' the emission of excessive greenhouse gases (GHGs) into the ambient environment. While methane emissions from agriculture and livestock is one of the important elements of GHGs, it is also required for growth of the agriculture and allied activities for all economic categories. The present study, under this backdrop, examines long run and short run linkages between methane emissions and agriculture outputs for high and low to upper middle-income countries for the period 1981-2012. The results show that the series of methane emissions and agriculture output are cointegrated in the 15 member Organization for Economic Co-operation and Development (OECD) group, low income and middle income countries signifying the responsibilities of these income groups in methane emissions. The responsible countries in the OECD are USA, UK, Japan, Germany, and Italy. Further, in short run dynamics, the Granger Causality results show that methane emissions make a cause to agriculture output for 15OECD and low-income countries, and agricultural output is a cause to methane generation for middle and all low to upper middle income countries. China, India, and Brazil cannot be blamed for making excessive methane generation as both the series are not cointegrated for them.
A Security Review of Event-Based Application Function and Service Component Architecture
Authors: Nabi Faisal , Yong Jianming , Tao Xiaohui
Published: July 2020

The term service component is derived from SCA (service component architecture) for event based distributed system design. Although service component pattern offers composite application development and support application reusability functionality. However, security in event based communication in components interaction model mostly discussed on upper layer in SCA while developing service oriented component application logic. This layer is called application business process logic layer, which produces the application's rendering logic, having being authenticated from ACL.The need for such a comprehensive security review is required in this field that could possibly elaborate the issues in composite application and Event based attack in service component architecture model. The paper achieves this target by analysing, reviewing the security issues, modelling techniques in service component application functionality, while application components, that produces, consume, and processing events.
A MACH Filter-Based Reconstruction-Free Target Detector and Tracker for Compressive Sensing Cameras
Authors: Braun Henry , Katoch Sameeksha , Turaga Pavan , Spanias Andreas , Tepedelenlioglu Cihan
Published: July 2020

Compressive sensing cameras hold the promise of cost-effective hardware, lower data rates, and improved video quality, particularly outside the visible spectrum. However, these improvements involve significant computational cost, as sensor output must be reconstructed in order to form an image viewable by a human. This paper describes a prototype automated detection and tracking system using a compressive sensing camera that does not rely on computationally costly image reconstructions. It operates on raw sensor data for an approximately ten-fold improvement in computation time over a comparable reconstruct-then-track algorithm. The detector is successful at a sensing rate of 0.3, comparable to that required for high-quality image reconstructions. If initialized with the location of a target, the tracker holds the target at a sensing rate of 0.005, below the boundary where reconstruction breaks down. These results show not only that direct tracking from compressive cameras is possible, but also give support to the pursuit of direct inference from compressive sensors of all types.
Analysis of Effective Routing Protocols for Flying Ad-Hoc Networks
Authors: Kumar Sudesh , Bansal Abhishek , Raw Ram Shringar
Published: July 2020

Recently, the flying ad-hoc network (FANETs) is a popular networking technology used to create a wireless network through unmanned aerial vehicles (UAVs). In this network, the UAV nodes work as intermediate nodes that communicate with each other to transmit data packets over the network, in the absence of fixed an infrastructure. Due to high mobility degree of UAV nodes, network formation and deformation among the UAVs are very frequent. Therefore, effective routing is a more challenging issue in FANETs. This paper presents performance evaluations and comparisons of the popular topology-based routing protocol namely AODV and position-based routing protocol, namely LAR for high speed mobility as well as a verity of the density of UAV nodes in the FANETs environment through NS-2 simulator. The extensive simulation results have shown that LAR gives better performance than AODV significantly in terms of the packet delivery ratio, normalized routing overhead, end-to-end delay, and average throughput, which make it a more effective routing protocol for the highly dynamic nature of FANETs.
Evaluation of SiC-MOSFET by Repetitive UIS Tests for Solid State Circuit Breaker
Authors: Sagara Mitsuhiko , Wada Keiji , Nishizawa Shin-Ichi
Published: July 2020

This paper investigates a degradation of SiC power device for DC circuit breaker through repetitive unclamped inductive switching (UIS) tests. Being much lower compared with Si devices, it has been considered an application for DC circuit breakers using SiC semiconductor. In order to use for the DCbreaker, it is essential to evaluate the destructive endurance for UIS test.This paper evaluates a deterioration phenomenon by paying attention to the decrease of the gate voltage of the SiC-MOSFETs under the degradation at repetitive UIS test.
High-Performance SIP Half-Bridge IPM Based on 35mΩ/1200V SiC Stack-Cascode
Authors: Alexandrov Peter , Bhalla Anup , Li Xue Qing , Eltze Jens
Published: July 2020

A SiC-based high-performance Intelligent Power Modules (IPM) was developed. It is a System In Package (SIP) module that consist of a half-bridge with driver. In the developed SIP IPM, the internal half-bridge is made up of UnitedSiC 35mΩ/1200V Stack-Cascode switches (UF3SC120035Z) which have low on-resistance, low gate charge, simple gate drive of VGS=0 or-5V to VGS=12V, excellent integral body diode and very low switching losses. The module operates with control voltage of 12-15V for both the low and high side switches, and a logic level input that can be 3.3V, 5V or 12V. We believe that this module will enable extremely efficient switching up to 250-400kHz, depending on topology, offering several hundred kHz even in hard-switched applications.
Improving Heat Conduction of Insulated Metal Substrate with Thermal Pyrolytic Graphite Core for SiC Power Module Packaging
Authors: Fan Wei , Wexler Garry , Gurpinar Emre , Ozpineci Burak
Published: July 2020

TPG-core IMS concept was jointly explored in this study. Integrating high thermally conductive TPG graphite core into IMS is expected to simultaneously achieve high thermal conductivity from TPG and electrical functionalities from IMS. Nearly 2x thermal conductivity and 30% weight saving was demonstrated on TPG-core IMS compared to conventional Cu-core IMS. Significant junction temperature reduction (11°C) in steady state and power cycling was revealed by the thermal analysis as the result of improved thermal spreading in plane and through the thickness. The study also proved the manufacturability and compatibility of this TPG-core IMS structure to the existing IMS production and power module assembling. The integration of TPG and IMS paves a new packaging route to increase heat load, improve reliability, simplify module design and reduce assembling cost and number of steps.
Effect of Proton and Electron Irradiation on Current-Voltage Characteristics of Rectifying Diodes Based on 4H-SiC Structures with Schottky Barrier
Authors: Strel'chuk Anatoly M. , Kozlovski Vitalii V. , Lebedev Alexander A.
Published: July 2020

Forward and reverse current-voltage (I-V) characteristics of commercial rectifying Schottky diodes (SDs) based on silicon carbide (4H-SiC, base layer doping level 3·1015 cm-3) have been studied under irradiation with 0.9 MeV electrons and 15 MeV protons. The starting diodes were characterized by a barrier height of ~1.5 eV and nearly ideal forward and reverse I-V characteristics. It was found that, at doses exceeding the threshold dose Dth, the series differential resistance Rs of the diodes grows as Rs ~ Dm (m = 10-15) and shows no tendency toward saturation. Dth ≈7·1015 cm-2 under electron irradiation, and Dth ≈ 4·1013 cm-2 in the case of irradiation with protons. Heating to 200oC results in that Rs decreases with activation energy of ~1.1 eV and Rs is partly annealed-out with activation energy of ~0.7 eV. The starting Schottky diodes changes only slightly under irradiation, but, possibly, the irradiation leads to an over-compensation of the n-type layer and formation of an additional barrier in the form of a pn junction.
Extreme Environment Integrated Circuits Based on Enhancement Mode SiC JFETs
Authors: Alexandrov Peter , O'Grady Matt
Published: July 2020

This paper presents results on developing high temperature capable SiC JFET based IC technology that can operate at temperatures up to 500 °C. All JFET devices are fully planar, formed by ion implantation, and the device design allows the use of semi-insulating or conductive SiC substrates. Basic analog and logic ICs were built in order to demonstrate the technology high temperature capability. All circuits used enhancement mode n-channel JFETs as active transistors, and depletion mode transistors as active loads. The logic circuits built included NOT, NAND, and NOR gates. The analog circuits built included a simple one-stage operational amplifier. JFETs and ICs were packaged in ceramic packages and tested at temperatures up to 500 °C.
Mono-Versus Poly-Crystalline SiC for Nuclear Applications
Authors: Huang Xian , Yeghoyan Taguhi , Gavarini Stéphane , Soulière Véronique , Millard-Pinard Nathalie , Ferro Gabriel
Published: July 2020

3C-SiC layers of different microstructures (monocrystalline (100) and (111) oriented and polycrystalline) were implanted with high energy (800 keV) 129Xe++ ions. Implantations were performed at room temperature (RT) and at 500 °C using two different fluences of Φ1 = 1x1016 and Φ2 = 1x1017 at/cm2. Surface blistering was only observed for RT and Φ2 implantations into poly-SiC material while mono-SiC kept rather smooth surface. This was due to more homogeneous Xe bubbles distribution (200 nm deep) in the mono-SiC than in the poly-SiC. Xe retention was found to be almost complete for all samples. Some Xe enhanced diffusion was detected in the poly-SiC material which was attributed to grain boundaries. Some irradiation-induced oxidation effect was evidenced, O element being located at the depth where Xe bubbles are accumulating. This was more pronounced for poly than for mono-SiC. These results demonstrate that SiC microstructure affects many aspects of its behavior upon Xe irradiation.
SiC Epitaxial Reactor Cleaning by ClF3 Gas with the Help of Reaction Heat
Authors: Kurashima Keisuke , Hayashi Masaya , Habuka Hitoshi , Ito Hideki , Mitani Shin Ichi , Takahashi Yoshinao
Published: July 2020

A silicon carbide epitaxial reactor cleaning process was designed accounting for the exothermic reaction heat between silicon carbide and chlorine trifluoride gas. To avoid the peeling of the susceptor surface coating film, the spontaneous temperature increase due to the exothermic reaction heat was moderated by adding the nitrogen gas. The particle-type silicon carbide deposition could be effectively removed without causing any damage of susceptor.
A New Permanganate-Free Slurry for GaN-SiC CMP Applications
Authors: Fang Treliant , Chen Ping Chung , Lee Ming Hsun
Published: July 2020

Single crystal SiC wafers are known to be extremely difficult to polish by conventional CMP slurries because of their high hardness and chemical resistance. Previously only those manganese-containing CMP slurries are capable of producing measurable and useful polishing rates with this versatile wide band-gap substrate. A new permanganate-free SiC polishing slurry containing a generic formula of MXO2 etchant, where M is an alkali metal, X is a halogen, O is oxygen is disclosed. When mixed with an abrasive powder in an aqueous slurry form, the tribochemical reactant that activates under pressure, etches SiC effectively, rendering an enhanced Material Removal Rate (MRR) when processing CMP SiC wafers. The MRR can sometimes go up to a few order of magnitudes, as compared to the abrasive slurry without these chemical etchants. The series of MXO2 compounds that can activate SiC polishing belong to the chemical family of halites. Sodium chlorite, NaClO2, the simplest and most available member of the halites family, is a good example. The accelerated polishing rates offer increased throughput of the slow SiC CMP process. The new slurry is particularly useful for non-oxide wafer polishing, which includes SiC, GaN and AlN wafers. An outstanding character of the new halite-based polishing formulation that is different from the current permanganate-based slurries is that the waste stream produced from the CMP process can be easily treated in the waste water treatment facilities because they do not contain toxic heavy metal ions such as manganese and permanganate in the polishing formulations. Continuous exhaustive CMP polishing test with 32 4” 4H-N SiC wafers using a production CMP tool containing 32L of the alumina-chlorite slurry has demonstrated an MRR of 1.7um/hr (Si-face) when the slurry is fresh, and a final MRR of 1.0um/hr after 16 hours polishing at 800mL/min slurry flow rate with pH buffer control without fresh oxidant addition. The resulting 32 polished 4H-SiC test wafers show overall excellent smooth surface roughness with the best Ra of 0.05nm by AFM after fine CMP polishing.
Anomalous Conduction between the Band and Nearest-Neighbor Hopping Conduction Regions in Heavily Al-Doped p-Type 4H-SiC
Authors: Hidaka Atsuki , Takeshita Akinobu , Ogawa Kohei , Imamura Tatsuya , Takano Kota , Okuda Kazuya , Matsuura Hideharu , Ji Shi Yang , Eto Kazuma , Mitani Takeshi , Kojima Kazutoshi , Kato Tomohisa , Yoshida Sadafumi , Okumura Hajime
Published: July 2020

We measure the temperature-dependent resistivity (ρ(T)) for thick heavily Al- and Ncodoped p-type 4H-SiC samples grown by chemical vapor deposition (CVD), physical vapor transport (PVT), and solution growth (SG), and investigate their conduction mechanisms. For samples with an Al concentration (CAl) of 3.5×1019 to 1×1020 cm-3 grown by CVD, PVT, and SG, the conduction mechanisms at high and low temperatures are band and nearest-neighbor hopping (NNH) conduction, respectively. In the range CAl of 1×1019 to 3.5×1019 cm-3, on the other hand, an anomalous conduction, referred to as X conduction here, is observed between the band and NNH conduction regions for the samples grown by CVD and PVT, but not those grown by SG. One of the differences between the samples grown by CVD and PVT and those grown by SG is the off-orientation toward [11-20] of the (0001) 4H-SiC substrate. We discuss the reason for the appearance of X conduction, which appears to be consistent with dopant-concentration inhomogeneity model.
Evaluation of p-Type 4H-SiC Piezoresistance Coefficients in (0001) Plane Using Numerical Simulation
Authors: Sugiura Takaya , Takahashi Naoki , Nakano Nobuhiko
Published: July 2020

A numerical simulation of p-type 4H-Silicon Carbide (4H-SiC) piezoresistance coefficients in (0001) plane evaluation is shown in this study. A 4H-SiC material has outstanding material characteristics of wide band-gap of 3.26 eV and high temperature robustness. However, many material properties of 4H-SiC material are still unknown, including piezoresistance coefficients. Piezoresistive effect is resistivity change when mechanical stress is applied to the material. Piezoresistance coefficients express the magnitude of this effect, important for designing a mechanical stress sensor. In this study, reported piezoresistance coefficients of p-type 4H-SiC in (0001) plane is evaluated based on numerical simulation. The simulated results of Gauge Factor (GF) values (determined by (ΔR/R)/ε (R is the resistance and ε is the strain of material)) well matched to the theoretical GF values (determined by πE (π is the piezoresistance coefficient and E is Young’s modulus of the material)), shows that reported piezoresistance coefficients are reliable. Also, the internal mappings of piezoresistive effect from the numerical simulation are shown, useful to understand piezoresistive effect which is difficult to see by experimental results.
Photoluminescence Characterization of Fluorescent Sic with High Boron and Nitrogen Concentrations
Authors: Tanaka Daiki , Lu Wei Fang , Kamiyama Satoshi , Iwaya Motoaki , Takeuchi Tetsuya , Akasaki Isamu
Published: July 2020

The dependence of optical properties on impurity concentrations and excitation power was explored. In particular, it was found that the peak shift of photoluminescence (PL) is proportional to the boron concentration. This might be due to donor–acceptor pair (DAP) recombination via double deep acceptor levels (D-centers), where the occupancy of the D*-center increased with the B concentration, and the recombination via the D*-center for longer wavelengths became dominant. Moreover, the relative constants B and C were calculated by BC model fitting from the internal quantum efficiency (IQE) curve as a function of excitation power. The theoretical extrapolation based on BC model predicted that high impurity concentrations are sufficient to suppress the droop phenomenon of efficiency induced by the increased excitation power.
Optically Detected Magnetic Resonance Study of 3D Arrayed Silicon Vacancies in SiC pn Diodes
Authors: Yamazaki Yuichi , Chiba Yoji , Sato Shin Ichiro , Makino Takahiro , Yamada Naoto , Satoh Takahiro , Kojima Kazutoshi , Hijikata Yasuto , Tsuchida Hidekazu , Hoshino Norihiro , Lee Sang Yun , Ohshima Takeshi
Published: July 2020

We demonstrated optically detected magnetic resonance (ODMR) measurements using three-dimensional (3D) arrayed silicon vacancies (VSis) in in-plane SiC pn diodes. Proton beam writing successfully created 3D arrayed VSis using different ion (proton) energies. The results of PL mapping analysis indicate that the features of luminescent spot such as size and depth can be estimated by a Monte Carlo simulation (SRIM). This suggests that diagnosis at any locations in SiC devices can be realized using VSi quantum sensors. Luminescent spots with different depth ranging 4-60 μm showed similar ODMR spectra including its contrast, which means that a similar sensor sensitivity is expected. The results suggest that 3D arrayed VSi can act as quantum sensor elements with uniform sensitivity in SiC devices.
Statistical Analysis of Killer and Non-Killer Defects in SiC and the Impacts to Device Performance
Authors: Das Hrishikesh , Sunkari Swapna , Justice Joshua , Pham Helen , Park George , Seo Young Ho
Published: July 2020

Multi-channel defect detection in epitaxial SiC layers is used to detect and classify various extended defects. The effects of the killer defect category are analyzed on hundreds of production diode and MOSFET wafers. Invariably, the number of these killer defects sets the yield entitlement for each wafer, and electrically, they fall into a few expected failure bins depending on their position on the die. A variety of non-killer defects like Bar Stacking Faults (BSFs), V-type defects, isolated micro-pipe related bumps, stacking faults, scratches and deep pits are identified in over thousand die each, and their effect on fully fabricated diode and MOSFET products are determined at wafer sort. A very high percentage of the die containing these non-killer defects pass all electrical tests including the rigorous Unclamped Inductive Switching (UIS) testing. Specifically, a population of electrically passing die, containing BSFs, are identified and packaged for High Temperature Reverse Bias (HTRB) tests. Every BSF containing die passes both forward and reverse 1000-hour HTRB drift tests.
Evolution of SiOx Shell Layers on SiC-SiOx Core-Shell Nanowires
Authors: Broggi Andrea , Ringdalen Eli , Tangstad Merete
Published: July 2020

Composite core-shell SiC-SiOx nanowires can be produced by heating quartz and SiC powders, with addition of Ar(g) or He(g). The two powders are mixed to create pellets, which will react to SiO(g) and CO(g) at elevated temperatures. The two gases will react on a colder surface, producing a web of SiC-SiOx nanowires. The product serves as a precursor for SiC nanowires production. During the process, silicon and oxygen accumulate at high energy points, forming SiOx nodules. Nodules can either generate in proximity of stacking faults, or where two or more nanowires are close to each other. The present work investigates the role of crystal defects in the wettability between silica and silicon carbide. Samples were collected and analyzed under Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The results show that β-SiC grows mainly in the [111] direction. Crystal defects are located in the SiC core-phase. SiOx initially develops a uniform layer as thick as the core-phase itself. SiOx nodules would first form where the defects are present, by accumulating at high energy sites. Droplets on a flat surface imply poor wettability. The mechanism of formation of the nodules is compared to two earlier proposed theories. In conclusion, the wettability of SiOx and SiC at nanoscale is controlled by the presence of crystallographic defects. Continuous SiOx layers and bead-like structures can be found in the same temperature interval. The microstructural changes depend on the local energy balance.
Surface Treatment of 4H-SiC MOSFETs Prior to Al2O3 Deposition
Authors: Idris Muhammad Idzdihar , Horsfall Alton B.
Published: July 2020

The effect of surface treatments prior to the deposition of Al2O3 is performed on 4H-SiC MOS capacitors and MOSFETs. 40 nm of Al2O3 were deposited on 4H-SiC using atomic layer deposition (ALD) as a gate dielectric. Different surface treatments were used to investigate the capacitance-voltage and current-voltage characteristics on MOS capacitors and MOSFETs respectively, including the important parameters such as interface state density, flat band voltage, threshold voltage and field-effect mobility. Forming gas annealing and rapid oxidation processes were found to be effective in reducing the interface state density and results in high field-effect mobility with peak field-effect mobility of 130 cm2Vs-1. The experimental results obtained manifest that the surface treatment prior to Al2O3 deposition is critical to producing high performance of 4H-SiC MOSFETs.
An Approach to Predict 4H-SiC Wafer Bending after Back Side Thinning by Substrate Resistivity Analysis
Authors: Piluso Nicolo , Rinaldi Stefania , Lorenti Simona , Bassi Anna , Severino Andrea , Coffa Salvo
Published: July 2020

It is commonly thought that, in the development of SiC power devices with low on-state resistance (Ron), several critical processes in the device fabrication line can strongly impact the final warpage of wafers. High warpage would lead to bad definition of masks, preventing uniform deposition of resist materials and disturbing the normal handling procedures. All these factors would then result in a potential decrease of the electrical yield of the devices, especially for MOSFETs. This study reveals the lack of correlation between critical line processes such as epitaxial growth, oxidations, ion implantations, annealing processes with the final bending of wafers. Conversely, a strong dependence with the resistivity of the substrates is observed. A new parameter defined as RMR (Resistivity Modulation Rate) is taken proposed and, together with the starting value of ingot resistivity, this parameter shows a strong relationship with the final warpage after wafer thinning. A safe region having warpage low enough to allow the workability of the wafers is found.
X-Ray Topography Characterization of Large Diameter AlN Single Crystal Substrates
Authors: Dalmau Rafael , Britt Jeffrey , Fang Hao Yang , Raghothamachar Balaji , Dudley Michael , Schlesser Raoul
Published: July 2020

Large diameter aluminum nitride (AlN) substrates, up to 50 mm, were manufactured from single crystal boules grown by physical vapor transport (PVT). Synchrotron-based x-ray topography (XRT) was used to characterize the density, distribution, and type of dislocations. White beam topography images acquired in transmission geometry were used to analyze basal plane dislocations (BPDs) and low angle grain boundaries (LAGBs), while monochromatic beam, grazing incidence images were used to analyze threading dislocations. Boule diameter expansion, without the introduction of LAGBs around the periphery, was shown. A 48 mm substrate with a uniform threading dislocation density below 7.0 x 102 cm-2 and a BPD of 0 cm-2, the lowest dislocation densities reported to date for an AlN single crystal this size, was demonstrated.
The Waffle Substrate: A Novel Approach to Reducing Substrate Resistance in SiC Power Devices
Authors: Opondo Noah , Cooper James A. , Liao Hang Jie , Chen Wei Nong , Morisette Dallas
Published: July 2020

Silicon carbide (SiC) is enabling the next generation of semiconductor power devices, with performance orders-of-magnitude beyond silicon. The most important power switching device is the SiC power MOSFET, whose performance is limited by three main resistance elements: the channel, drift layer, and substrate. For blocking voltages in the range of 400-900V, substrate resistance is a major limitation. Wafer thinning is currently used to reduce the substrate resistance, but this also reduces the strength of the wafers. We report on a waffle substrate technique that relies on wafer thinning and inductively coupled plasma (ICP) etching to reduce the substrate resistance below levels achievable by thinning alone, while retaining the mechanical stability of a moderately-thinned substrate. This technique can be applied to any SiC device for which substrate resistance is a limitation.
Investigation into the Body Diode Degradation of 6.5 kV SiC MOSFETs
Authors: Bianda Enea , Mihaila Andrei , Romano Gianpaolo , Knoll Lars , Wirths Stephan , Torresin Daniele
Published: July 2020

The aim of this study is to investigate the main contributing factors to the degradation of the intrinsic body diode in SiC MOSFETs, caused by the expansion of stacking faults (SFs) from the substrate into the epitaxial layer, and how it affects their performance. Additionally, a comparison between DC forward current stress and surge current pulse stress is shown.
Avalanche Ruggedness Assessment of 1.2kV 45mΩ Asymmetric Trench SiC MOSFETs
Authors: Deng Xiao Chuan , Zhu Hao , Li Xuan , Xu Xiao Jie , Zhou Kun , Li Zhi Qiang , Bai Song , Zhang You Run , Zhang Bo
Published: July 2020

In this paper, avalanche ruggedness of the commercial 1.2kV 45mΩ asymmetric silicon carbide (SiC) metal oxide semiconductor field effect transistor (MOSFET) is investigated by single-pulse unclamped inductive switching (UIS) test. The avalanche safe operation area (SOA) of the MOSFET is established. The impact of inductance and temperature on avalanche capability is exhibited, which is valuable for many application circuits. The variation in critical avalanche energy with peak avalanche current, peak avalanche current with avalanche time, and temperatures dependence of critical avalanche energy are confirmed.
Improved SiC MOSFET SPICE Model to Avoid Convergence Errors
Authors: Lefdal Hove Haavard , Spro Ole Christian , Guidi Giuseppe , Peftitsis Dimosthenis
Published: July 2020

This paper presents improvements to a SPICE model for a commercially available SiC MOSFET to avoid convergence errors while still providing reliable simulation results. Functionality in the internal part of the model that shapes the transconductance of the device according to its junction temperature and gate-source voltage dependency has been improved to provide a continuous characteristic rather than the initial discontinuous performance. Furthermore, the output characteristics from the initial and the proposed model have been compared to lab measurements of an actual device. The results show that the proposed and initial model provide equally reliable simulation results. However, the proposed model does not run into convergence problems.
1.2 kV, 10 A, 4H-SiC Bi-Directional Field Effect Transistor (BiDFET) with Low On-State Voltage Drop
Authors: Kanale Ajit , Cheng Tzu Hsuan , Han Ki Jeong , Baliga B. Jayant , Bhattacharya Subhashish , Hopkins Douglas
Published: July 2020

Bidirectional power switches are used in matrix-or cyclo-converters and in multistage inverter circuits to facilitate high-frequency AC-to-AC conversion. A new 1.2 kV bidirectional MOSFET (BiDFET) with low on-resistance is achieved and demonstrated using two discrete SiC power MOSFET bare die chips, packaged within a four-terminal custom-designed module. Static and dynamic characterization has been carried out to inspect the on-state and switching behaviour of the BiDFET. The BiDFET is shown to have a low forward voltage drop of 0.6 V at a current of 10 A, which is more than 2.5x smaller than previous Si IGBT and SiC MOSFET based bidirectional switch implementations.
Mechanisms of Heavy Ion-Induced Single Event Burnout in 4H-SiC Power MOSFETs
Authors: McPherson Joseph A. , Hitchcock Collin W. , Chow T. Paul , Ji Wei , Woodworth Andrew A.
Published: July 2020

This paper describes the mechanisms behind the failure of silicon carbide (SiC) Power MOSFETs (metal oxide semiconductor field effect transistors) when struck by a heavy ion. The modeled device is designed to simulate a commercially available 1200 V power MOSFET under the strike of a silver ion with a Linear Energy Transfer (LET) of 46 MeV-cm2/mg commonly used in single event effect (SEE) testing. The device is shown in simulation to fail near 500 V, which is in close agreement to experiments. The failure occurs near the interface between the epitaxial layer and the substrate layer due to the rapid increase of the electric field in that region and destruction of the device from impact ionization. Two improved designs were proposed and investigated that would help to mitigate the electric field in these regions and improve the device’s tolerance to single-event burnout (SEB). The new designs increased the voltage at which SEB occurs from 500 V to over 900 V and increased the specific on-resistance (Ron,sp) by only 5%.
Revisiting the Site-Competition Doping of 4H-SiC: Cases of N and Al
Authors: Ferro Gabriel , Chaussende Didier
Published: July 2020

Because the well-known site-competition and step-controlled epitaxy rules cannot reasonably describe all the incorporation processes of the main impurities (Al and N) into 4H-SiC during epitaxy, the concept of replacement incorporation was proposed and applied to explain the experimental results published so far. In this model, the transient formation of C or Si vacancies at the surface or sub-surface of terraces is proposed to play a key role by destabilizing the impurities sitting on them. In addition to the availability of these vacancies at the surface, desorption was proposed to be a very important limiting process for Al incorporation while only occasionally relevant for N incorporation. The main 4H-SiC epitaxial growth parameters are reviewed and discussed according to the proposed replacement model.
Renal function in the third year among very low birth weight infants fed by supplemental proteins
Authors: Bordbar Arash , Vahid Azade Noroozi , Kashaki Mandana
Published: July 2020

Very Low Birth Weight (VLBW) infants have higher nutritional needs than term infants. Energy and protein are two important factors influencing their growth. Breastfeeding is not enough to meet VLBW infants’ needs, for this reason, complementary protein is required by them. Hence, the present study aimed at investigation of renal function among VLBW infants receiving complementary proteins. The study was conducted on two groups of intervention and control (n= 18 in each group) (Case study: VLBW infants born in Akbarabadi hospital of Tehran in 2014 2015). The intervention group includes 3-year-old children who weighting less than 1200 grams at birth and have received protein supplementation at the course of NICU hospitalization, protein was added to maternal milk when the amount of milk reaches to 100 cc/kg/day, at this time parenteral nutrition was discontinued and the volume of feeding was increased 20cc/kg/day until reached to 150-180cc/kg/day. We also added the fortifier to breast milk at this time. The fortification and the protein supplementation were stopped when the weight of the baby reached to 1500 grams. The control group was fed similar to the intervention group but had received no complementary protein . The renal function was evaluated by measuring such criteria as BUN, Cr, ALB and U/A. After data collection, a statistical analysis was performed using SPSS software Ver. 22. Following to BUN evaluation, a significant correlation was seen between BUN and received protein (p-value=0.010). However, there was no significant correlation between Cr and received protein as well as mean values of the two groups (p-value=0.0766). Similarly, an insignificant correlation was found between the two groups following to investigation of ALB (p-value=0/257), while the mean values of the two groups were similar. The both groups were also equal in U/A. The complementary protein increased the BUN with no effect on Cr, ALB and U/A, providing no impact on renal function. Therefore, complementary protein intake made no conflict in renal function.
Robotic surgery of head and neck cancers, a narrative review
Authors: Kalantari Farbood , Rajaeih Shahin , Daneshvar Ali , Karbasi Zahra , Mahdi Salem Mohammad
Published: July 2020

Head and neck cancers are the most common cancers in the body. Treatments are determined on the basis of the location and stage of the primary tumor. The goal of treatment is to eliminate the tumor, prevent recurrence or metastasis, and maintain the quality of life. There are several treatments available for the management of head and neck cancers, including surgery, radiation therapy, chemotherapy, new molecular agents, and a combination of them. Transoral robotic technique is a short-time operation using a type of robotic machine in which the patient undergoes anesthesia for a shorter time and the side effects of this operation and the time of hospitalization are less than open surgery. Due to the importance of speed and accuracy in head and neck cancer surgery and the importance of application of robotics in surgery, the present study was designed and implemented to review the application of robotics in the management of head and neck cancers. In this review study, the keywords: application, robotic, surgical, head cancer, transoral robotic surgery (TORS), and neck cancer, were searched in ISI, PubMed, Scopus, Google scholar databases. Related articles written domestically or abroad that have covered areas such as the background of transoral robotic surgery, maintaining organ function and approaches, the advantages and disadvantages of TORS, the affordability of TORS, the combination of TORS with other therapeutic approaches published from 2003 to 2019 were reviewed. The use of robotic surgery for precise operations such as head and neck cancers seems to be essential. More advanced robotic devices are expected to expand the surgery treatment for head and neck cancers as well as the results of using TORS for oncologic optimization and acceptability of results while maintaining organ function and patient's quality of life.
Mechanotendography in Achillodynia shows reduced oscillation variability of pre-loaded Achilles tendon: a pilot study
Authors: Schaefer Laura , Bittmann Frank
Published: July 2020

The present study focuses on an innovative approach in measuring the mechanical oscillations of pre-loaded Achilles tendon by using Mechanotendography (MTG) during application of a short yet powerful mechanical pressure impact. This was applied on the forefoot from the plantar side in direction of dorsiflexion, while the subject stood on the ball of the forefoot on one leg. Participants with Achilles tendinopathy (AT; n = 10) were compared to healthy controls (Con; n = 10). Five trials were performed on each side of the body. For evaluation, two intervals after the impulse began (0-100ms; 30-100ms) were cut from the MTG and pressure raw signals. The intrapersonal variability between the five trials in both intervals were evaluated using the arithmetic mean and coefficient of variation of the mean correlation (Spearman rank correlation) and the normalized averaged mean distances, respectively. The AT-group showed a significantly reduced variability in MTG compared to the Con-group (from p = 0.006 to p = 0.028 for different parameters). The 95% confidence intervals (CI) of MTG results were disjoint, whereas the 95% CIs of the pressure signals were similar (p = 0.192 to p = 0.601). We suggest from this work that the variability of mechanical tendon oscillations could be an indicative parameter of an altered Achilles tendon functionality.
When COVID-19 affects muscle: effects of quarantine in older adults
Authors: Moro Tatiana , Paoli Antonio
Published: July 2020

At the beginning of 2020 a respiratory diseased named COVID-19 rapidly spread worldwide. Due to the presence of comorbidities and a greater susceptibility to infections, older adults are the population most affected by this pandemic. An efficient pharmacological treatment for COVID-19 is not ready yet; in the meanwhile, a general quarantine has been initiated as a preventive action against the spread of the disease.  If on one side this countermeasure is slowing the spread of the virus, on the other side is also reducing the amount of physical activity. Sedentariness is associated with numerous negative health outcomes and increase risk of fall, fractures and disabilities in older adults. Models of physical inactivity have been widely studied in the past decades, and most studies agreed that is necessary to implement physical exercise (such as walking, low load resistance or in bed exercise) during periods of disuse to protect muscle mass and function from catabolic crisis. Moreover, older adults have a blunted response to physical rehabilitation, and a combination of intense resistance training and nutrition are necessary to overcome the loss of in skeletal muscle due to disuse.
Le tecniche e le soluzioni utilizzate nella detersione delle ulcere: una revisione della letteratura
Authors: Vitale Elsa , De Angelis Lucia Rosa , Germini Francesco
Published: July 2020

L’ulcera è la perdita di continuità dell’epitelio, dell’epidermide o della mucosa causata dall’espulsione del tessuto necrotico infiammato. È l’espressione di processi degenerativi provocati da fenomeni infiammatori, infettivi, da disturbi circolatori o da danneggiamento tissutale per cause chimiche e fisiche. Il trattamento di una lesione cutanea cronica deve essere multidisciplinare e richiedere la collaborazione di numerosi specialisti, del personale infermieristico, del paziente e/o del nucleo familiare. Lo scopo della revisione è quello di verificare gli effetti della detersione sulle ferite considerando sia gli approcci adottati, sia le soluzioni utilizzate, valutando i relativi tassi di guarigione e di infezione delle ulcere. La ricerca della letteratura è stata eseguita nelle banche dati di Pubmed e Cochrane Library. Sono stati considerati studi clinici randomizzati e revisioni di letteratura dal 2003 al 2018. 276 lavori scientifici sono stati individuati. Di questi, sono 15 studi sono stati considerati potenzialmente eleggibili. Successivamente alla lettura completa di ciascun lavoro sono stati inclusi infine 6 articoli. La gestione delle ulcere coinvolge molte figure professionali esperte in wound care che dovrebbero collaborare tra loro per guarire le ferite. Specificamente la detersione viene considerata un intervento di routine che viene effettuato con soluzione fisiologica sterile attraverso il metodo del tamponamento, questo perché la letteratura non fornisce ricerche soddisfacenti nell’ambito dell’utilizzo dell’acqua di rubinetto.
Colon Cancer Care of Hispanic People in California: Paradoxical Barrio Protections Seem Greatest among Vulnerable Populations
Authors: Escobar Keren M. , Sivaram Mollie , Gorey Kevin M. , Luginaah Isaac N. , Kanjeekal Sindu M. , Wright Frances C.
Published: July 2020

Background

We examined paradoxical and barrio advantaging effects on cancer care among socioeconomically vulnerable Hispanic people in California.

Methods

We secondarily analyzed a colon cancer cohort of 3,877 non-Hispanic white (NHW) and 735 Hispanic people treated between 1995 and 2005. A third of the cohort was selected from high poverty neighborhoods. Hispanic enclaves and Mexican American (MA) barrios were neighborhoods where 40% or more of the residents were Hispanic or MA. Key analyses were restricted to high poverty neighborhoods.

Results

Hispanic people were more likely to receive chemotherapy (RR=1.18), especially men in Hispanic enclaves (RR=1.33) who were also advantaged on survival (RR=1.20). A survival advantage was also suggested among MA men who resided in barrios (RR=1.80).

Conclusions

The findings were supportive of Hispanic paradox and MA barrio advantage theories. They further suggested that such advantages are greater for men, perhaps due to their greater spousal and extended familial support.
Increasing Vegetable Intake 400 G/Day to Control Body Weight and Lipid Profile in Overweight Hyperlipidemia Menopausal Women
Authors: Kartiko Sari Indri , Utari Diah Mulyawati , Kamoshita Sumiko , Oktaviana Dwi , Sakai Seigo , Nishiyama Hiroshi , Masuda Yasunobu , Yamamoto Shigeru
Published: July 2020

Background

Indonesia suffers growing health problems such as obesity, diabetes, and other metabolic syndromes with dietary habit as one of risk factors. To control the lipid and glycaemic profile, high fibre intake has been recommended. This study administered 400g/day vegetable intake with its fiber contents and observed the effects in lipid profile and glycaemic control.

Design

A parallel study of 30 pairs of menopausal women match paired in overweight, menopause, hyperlipidaemia, age, etc randomly divided into two groups (vegetable and control). The baseline data obtained from questionnaire and preliminary bloodwithdrawn of consented participants, then matched the characteristics included the results of lipid profile and glycated albumin. The administration was conducted for 21days by providing 400g/day of vegetable to the vegetable group subjects. Nutrition assessments were conducted at the baseline, middle, and final period. The data were analysed by using the unpaired and paired t-test.

Results

Significant results (p<0.05) were seen in biochemical variables in the lipid profile of total cholesterol, LDL cholesterol, and HDL cholesterol and body weight and BMI within the vegetable group. Significant results for the same variables were shown between vegetable and control group at the final data (p<0.05). The nutrition assessments result showed significances (p<0.05) within vegetable group and between two groups on the final data. After 21 days, significant decreases were found on the intakes of energy, lipids, carbohydrates (p<0.05), while vegetable intake and fiber intake showed significant increases (p<0.05).

Conclusion

These data suggest that maintaining a healthy diet of 400g/d vegetable can be effective in weight management and lipid profile control.
Implementation of Smoke-Free Law in Denpasar Bali: Between Compliance and Social Norms of Smoking
Authors: Suarjana Ketut , Astuti Putu Ayu Swandewi , Artawan Eka Putra I Wayan Gede , Duana Made Kerta , Mulyawan Ketut Hari , Chalidyanto Djazuly , Qomaruddin Mochammad Bagus , Wahyuni Chatarina Umbul
Published: July 2020

Background

Since 2013, City of Denpasar government has adopted a smoke-free law. Implementation of the law faces several obstacles, partly due to the high social acceptability of smoking in the city, where cigarette and smoking has been deeply engrained within social life and become part of hospitality. This study aims to assess the smoke-free law compliance and to explore the social norms that may affect the compliance.

Design and methods

The study was a mix of cross-sectional compliance survey and qualitative exploration conducted in Denpasar in 2019. Survey included 538 samples, which were selected using stratified random sampling and a walking protocol. The qualitative data was collected through in-depth interviews and Focus Group Discussion (FGD) in four sub-districts of Denpasar.

Results

Of the 538 venues, 32.9% complied with the seven compliance indicators. The university has the highest compliance (83.3%), while public places including worship places have a low compliance. The three most common violations were the absence of no-smoking signage (58.6%), provision of ashtray (17.5%), and smell of tobacco smoke (15.8%). The poor compliance was related to the lack of awareness of the regulation, and the fact that smoking is highly acceptable and part of the culture. The informants highlighted the essential role of public figures and potency of local policy as social disapproval of smoking.

Conclusions

Compliance to the smoke-free law in Denpasar remains low, continuous education, socialization and improved supervision are crucial. Meanwhile, social and cultural acceptance of smoking is considered as an essential factor that hampers the implementation of the smoke free law.