bluuebunny/crossref_metadata_2025 huggingface dataset:
Dangerous Women Feminism
Authors: Allmark Panizza
Published: July 2020

In the last 10 years, feminism has been foregrounded in popular music more than at any time. At the same time, female pop music artists have been the target of hostility because of the feminist messages they espouse. This chapter examines US-based female popular music artists who have embraced a postfeminist agenda. This agenda engages messages of empowerment, sex positivity, and elements of girl culture. In addition, this chapter explores the notion of resilience in relation to how these music artists have used the voice of feminism to become outspoken and show independence and strength in celebrating the female body. In particular, the author discusses the discourse of their concert tours, as this is a time when these artists are in the spotlight through both their performance and the promotional materials for those performances and as a consequence are more open (and vulnerable) to critique than at other times.
The Ungovernable Female Agency
Authors: Yanıkkaya Berrin
Published: July 2020

By following McNay's conceptualization of agency and adapting Mills' feminist stylistics, this chapter examines the creation of female agency and subjectivity in the Mexican political drama Ingobernable [The Ungovernable]. The series has two complete seasons and 27 episodes so far. The plot revolves around the actions of five women, who can be identified with their unexpected and unanticipated as well as disobedient and resistant behaviors at varying levels. Each woman has different relations with power; however, all aim to engender change within the established order. Here, the author proposed a multi-layered method for analyzing female agency and subjectivity in the series by weaving the analysis through women archetypes from Mexican history and argued that female agency is created through audacious and cautious actions in Ingobernable which exists in-between these two action-based tensions.
Voicing Women's Desire With a Camera
Authors: Tsao Evangeline
Published: July 2020

Conventional theorization of Western visual culture characterized the female form as passive objects that cater to men's viewing pleasure. This raises the questions of how women might take control over their self-representation to communicate their subjective sexuality, and to reclaim visual narratives of their own desire. This chapter discusses the activist potential of auto-photography, a practice that involves self-imaging and self-analysis, for women to actively voice their understanding and experience of desire. Drawing upon practices in art and in an empirical project of ‘photographing desire', it argues that the method enables consciousness-raising, and the materials generated can counter dominant discourse and unveil the diverse, underrepresented women's desire, thus having the potential of empowering women.
Tolerance of Microorganisms to Heavy Metals
Authors: Nyika Joan Mwihaki
Published: July 2020

Heavy metal pollution is a growing environmental concern due to the increase in anthropogenic-based sources. Microorganisms have high adsorptive capacities and surface-area-to-volume ratio that enable the uptake of these contaminants and their conversion to innocuous complexes in the process of bioremediation. This chapter explores the mechanisms and specific microorganisms that are resistant to metal toxicity. A wide range of bacterial, algae, and fungal species used as biosorbents are highlighted. Mechanisms such as reduction of metal cations, their sequestration, and binding on cell barriers are discussed. To optimise the efficacy of microorganisms in bioremediation processes, adoption of genetic and nano-technologies is recommended.
The Use of Microorganism-Derived Enzymes for Bioremediation of Soil Pollutants
Authors: Nyika Joan Mwihaki
Published: July 2020

Contamination of soils by xenobiotic compounds is a growing concern for environmentalists amidst the rise of anthropogenic activities that encourage such contamination practices. The use of microbial enzymes is a viable alternative to degrade and mineralize these contaminants, which is a growing research interest owing to its eco-friendly nature. This chapter explores the categories of enzymes used in soil bioremediation such as oxidoreductases and hydrolases, their mechanism of action, and their merits and demerits. Furthermore, molecular biology techniques useful in enhancing the production capacity, stability, activity, and shelf life of bioremediation enzymes is discussed. Ultimately, the need to develop bioremediation enzymes in bulk, using cheap technologies while optimising their activity, stability, and shelf life for effective soil decontamination is emphasized.
Role of Bacterial Chromate Reductase in Bioremediation of Chromium-Containing Wastes
Authors: Dey Satarupa
Published: July 2020

Chromium toxicity is a major environmental concern as it is the chief environmental pollutant released by paint, stainless steel, and mining industries. In nature, chromium exists in two stable valance states: Cr(VI) and Cr(III). Cr(VI) is highly toxic and soluble at neutral pH, whereas Cr(III) is insoluble at normal pH and is less toxic. Thus, it is essential to draw strategies for mitigation of Cr(VI), and microbial reduction of toxic Cr(VI) has been identified as a bioremediation technique not only to detoxify chromium but also to recover the non-toxic Cr(III) by physical means. Chromate reductase, the central enzyme involved in bioreduction of Cr(VI) to Cr(III) may be both intracellular as well as extracellular in nature. Most of the chromate reductase enzyme belongs to the oxidoreductase group such as nitroreductase, iron reductase, quinone reductase, hydrogenase, flavin reductase, as well as NAD(P)H-dependent reductase. Detailed analysis of the structure of the enzymes will help us in the suitable application of these enzymes in bioremediation of metal-contaminated wastes.
Phytoremediation
Authors: Pal Suparna
Published: July 2020

This chapter includes the sources of cadmium and chromium contamination of soil and various detrimental effects on plants and animals. Ecofriendly approach of soil clean up by phytoremediation is the main focus of the author. Heavy metal-induced oxidative stress of plants and their detoxification potentiality has been discussed here to create a wholesome idea about the basic and acute need of phytoremediation. Both enzymatic and non-enzymatic antioxidative defense mechanisms and various other biochemical parameters of metal hyperaccumulator plants are mentioned.
Challenges in the Business Model of Low-Cost Airlines
Authors: Rodríguez-García María , Orero-Blat Maria , Palacios-Marqués Daniel
Published: July 2020

In recent decades, low-cost airlines have proliferated in the European market offering cheap tickets and increasing popularity. This business model, characterised by cost leadership, has been studied on numerous occasions. The case of the Irish airline Ryanair has presented different challenges over the last few years in relation to its stakeholders, who are shaping the sustainability of the current era of air travel. This business model should be adapted to the current demands of the market, such as corporate social responsibility or care for the environment. The functioning of low-cost airlines regarding the use they make of ERP management systems is also analysed. They aim to balance their cost strategy with the development of internal resources and capabilities for the company's long-term strategy. A major current challenge for low-cost airlines is the implementation of ERP management systems to make strategies oriented to the customer, sustainability, and corporate social responsibility.
Multimedia E-Learning Education in Nigeria and Developing Countries of Africa for Achieving SDG4
Authors: Matthew Ugochukwu O. , Kazaure Jazuli S.
Published: July 2020

Educationally, electronic media are the communication resources for those who offer and support education and those who are participating in educational activities. Achieving the Sustainable Millennium Development Goals (SDG) with respect to UNESCO recommendations for committing 15%-25% of the developing nations annual budget to education toward realizing SMDG Goal #4, emphasis is on quality and affordable education for all human beings. Notwithstanding the substantial advancement in education, access and involvement over the past years has not been encouraging. Globally, 262 million school aged children are out of school in 2017, while a reasonable number of school children and adolescents have still not been able to meet the minimum competence in reading and solving mathematics. This research established that networked teaching and e-learning education in the academic institutions physical teachings will provide theoretical and practical significance on the learning outcomes in reshaping the face of education in developing countries such as Nigeria.
Review of Fault Tolerance Frameworks in the Cloud
Authors: Rawat Ajay , Sushil Rama , Agarwal Amit
Published: July 2020

Fault tolerance is the most imperious issue in the cloud to provide reliable services. Inherent vulnerability to failure hampers the performance and reliability of cloud services. Hence, to achieve reliability, fault tolerance becomes a mandatory feature which is hard to implement due to the dynamic infrastructure and complex interdependencies. Numerous fault tolerance techniques have been developed in the literature to address the challenges of cloud reliability. A recent research survey presented in this paper attempts to integrate the different fault tolerance architecture. This study presents a critical research review on various existing fault tolerance techniques to improve services reliability, availability, and applications execution in the cloud. A comparative analysis, based on different critical metrics like failure prediction, detection strategy, failure history, VM placement, and limitations, of the reviewed framework systems is also included in the paper. This review intends to facilitate the development of the new fault tolerance technique for the cloud environment.
Construction of Lightweight Big Data Experimental Platform Based on Dockers Container
Authors: Ren Youli
Published: July 2020

To reduce the large data experiment platform construction cost and reduce the learning difficulty big data, this article is based on virtualization technology through the Docker software installed on the Linux system, using the Open VpN routing forwarding, using Java web technology, realizing the big data within the local area network (LAN) cluster environment fleetly, and constructed of lightweight data experiment platform. Through this platform, we can create a big data cluster with one key, provide a variety of experimental environments matching the courses, focus on the technology itself, and greatly improve learning efficiency. Experimental analysis shows that the proposed construction method has a host occupancy rate of around 10% and a memory occupancy rate of around 10%, and the system runs stably.
A Methodology and Case Study to Assess SCOR-Make Agility Measures Under Uncertainties
Authors: Akkawuttiwanich Piyanee , Yenradee Pisal
Published: July 2020

An assessment of agility is not an easy task since agility has been differently defined in literature, and it is not convenient to measure by experiment in practice. The objective of this paper is to propose a methodology to assess the agility performance under uncertainties based on level 1 of SCOR-Make process metric including the upside make flexibility (AG1.1), upside make adaptability (AG1.2), and downsize make adaptability (AG1.3). The proposed methodology consists of predictive models, which are a deterministic linear programming (LP) model and LP model with uncertainties, and algorithms to assess the agility measures. A case study of a bottled-water factory is conducted to demonstrate the application of the proposed methodology. The case study shows that the proposed methodology can effectively determine the agility measures. It can also be adapted to answer other agility related practical questions that are different from the SCOR definition.
Being Green and Social Responsibility
Authors: Smith Alan D.
Published: July 2020

Through a qualitative business case approach, three major manufacturing firms in Pittsburgh, PA were reviewed for their eco-friendly sustainability strategic initiatives and products/services. Undoubtedly, use of green best practices are value adding steps for a company may be initially difficult to justify spending the time and resources developing such a process. This is especially true when other core business needs are present, such as driving revenue, product development, and meeting governmental or consumer expectations. However, green and sustainability initiatives may not be currently dictated needs, but many companies feel strongly that charting such a course would be to their stakeholders' mutual advantage. As resources are being consumed more rapidly, it is logical to enact steps to ensure the sustainability of such scare resources. The added benefit of lower input needs greatly improves the companies' stances in their market while also adding to the firms' overall profitability.
Creating Sustainable Contribution to the Environment
Authors: Joseph Shaji , Kulkarni Apoorva Vikrant
Published: July 2020

In the current environment, there is an increased thrust to outsource manufacturing activities to developing countries. Countries such as India are actively inviting MNCs to partner with micro, small, and medium enterprises (MSMEs). It is assumed that these initiatives would act as an incentive to increase their economic development. As most of the national, international agencies and regulatory bodies focus on the larger companies it is often ignored to account for the contribution of MSMEs towards improving sustainability. As every nation-state has a vital role to play in ensuring the successful implementation of the sustainable development goals (SDGs), it is important to study and document the contribution of this sector towards SDGs. This article tries to document small but effective sustainable development initiatives by MSMEs. It tries to map the contribution of the four selected MSMEs towards SDGs. All these efforts are beyond the compliance requirement mandated to MSMEs in India.
Design for Software Risk Management Using Soft Computing and Simulated Biological Approach
Authors: Aggarwal Alankrita , Dhindsa Kanwalvir S. , Suri P. K.
Published: July 2020

The process of software evaluation is one of the key tasks that are addressed by the quality assurance teams so that the risks in the software suite can be identified and can be removed with prior notifications. Different types of metrics can be used in defect prediction models, and widely used metrics are source code and process metrics. A simulated environment for the entire process shall be generated for multiple scenarios and parameters so that the results and conclusion can be depicted in an effective way. The focus of research is to develop a narrative architecture and design for software risk management using soft computing and nature-inspired approach. The proposed approach titled simulated biological reaction (SBR) is expected to have the effectual results on multiple parameters with the flavor of soft computing-based optimization. The proposed approach shall be integrating the simulation of microbiological process in different substances and elements to produce a new substance.
Research on Root Locus Correction Algorithm in Automatic Control System
Authors: Zhai Weifang , Feng Juan
Published: July 2020

Aiming at the stability control of the automatic control system, this paper proposes a root locus correction scheme. By establishing the mathematical model of the control object and using the root locus correction method in the classical control theory, the design of the control system is completed. The simulation experiment of the control system is carried out in the MATLAB environment, and the key points of the scheme are summarized. The simulation results show that the scheme not only successfully achieves the stability control of the system, but also meets the expected performance index, which fully proves its correctness and effectiveness.
The Business Effects of Standardization for SMEs
Authors: Eto Manabu
Published: July 2020

Standardization activity is a type of open innovation, specifically an outbound-revealing open innovation. Through standardization activities, a given technology spreads, its effects extend to the market, and the market expands. However, in many cases, competition intensifies, and price competition occurs. To succeed as global businesses, SMEs should take a strategy known as “Niche Top” in Japan. Standardization activities are more likely to constitute a risk for SMEs. However, the Japanese government has established a system that actively encourages SMEs to standardize. The authors of this manuscript conducted interviews with companies that are targets of this standardization system and investigated how these companies expand their businesses through standardization activities while still securing profits. The results show that standardization by SMEs does not cause the dissemination of technology and the expansion of markets; rather, it helps such SMEs erect barriers to market entry through the creation of standards and plays a large role in securing shares in niche markets.
Graph Classification Using Back Propagation Learning Algorithms
Authors: Bera Abhijit , Ghose Mrinal Kanti , Pal Dibyendu Kumar
Published: July 2020

Due to the propagation of graph data, there has been a sharp focus on developing effective methods for classifying the graph object. As most of the proposed graph classification techniques though effective are constrained by high computational overhead, there is a consistent effort to improve upon the existing classification algorithms in terms of higher accuracy and less computational time. In this paper, an attempt has been made to classify graphs by extracting various features and selecting the important features using feature selection algorithms. Since all the extracted graph-based features need not be equally important, only the most important features are selected by using back propagation learning algorithm. The results of the proposed study of feature-based approach using back propagation learning algorithm lead to higher classification accuracy with faster computational time in comparison to other graph kernels. It also appears to be more effective for large unlabeled graphs.
Towards a Secure DevOps Approach for Cyber-Physical Systems
Authors: Abrahamsson Pekka , Botterweck Goetz , Ghanbari Hadi , Jaatun Martin Gilje , Kettunen Petri , Mikkonen Tommi J. , Mjeda Anila , Münch Jürgen , Duc Anh Nguyen , Russo Barbara , Wang Xiaofeng
Published: July 2020

With the expansion of cyber-physical systems (CPSs) across critical and regulated industries, systems must be continuously updated to remain resilient. At the same time, they should be extremely secure and safe to operate and use. The DevOps approach caters to business demands of more speed and smartness in production, but it is extremely challenging to implement DevOps due to the complexity of critical CPSs and requirements from regulatory authorities. In this study, expert opinions from 33 European companies expose the gap in the current state of practice on DevOps-oriented continuous development and maintenance. The study contributes to research and practice by identifying a set of needs. Subsequently, the authors propose a novel approach called Secure DevOps and provide several avenues for further research and development in this area. The study shows that, because security is a cross-cutting property in complex CPSs, its proficient management requires system-wide competencies and capabilities across the CPSs development and operation.
Corona Assisted Tuning of Gallium Oxide Growth on 3C-SiC(111)/Si(111) Pseudosubstrates
Authors: Reiprich Johannes , Isaac Nishchay Angel , Schlag Leslie , Hopfeld Marcus , Pezoldt Joerg , Jacobs Heiko O.
Published: July 2020

Gallium oxide was grown on silicon carbide substrates using a corona discharge assisted vapor phase epitaxy process and gold catalyst. It is shown that by implementing the corona discharge the morphology of the gallium oxide can be transformed. The excitation of the gas phase and the generation of excited species directly influence the growth morphology suppressing nanowire growth and supporting the transformation into heteroepitaxial growth.
High Temperature Gate Voltage Step-by-Step Test to Assess Reliability Differences in 1200 V SiC MOSFETs
Authors: Mengotti Elena , Bianda Enea , Wirths Stephan , Baumann David , Bettega Jason , Jormanainen Joni
Published: July 2020

In this paper, robustness and reliability differences related to the performance of the gate oxide of commercially-available 1200 V-rated planar and trench SiC MOSFETs have been investigated. Due to a thin gate oxide in SiC MOSFETs and to a naturally imperfect interface of the oxide layer (SiO2) with the SiC material, its quality and reliability become very important and could be a limiting factor of the SiC technology when compared to the Si one. A dedicated gate oxide step-by-step (VG SbS) tester has been prepared during which the gate voltage is varied with different profiles. Results of Fowler-Nordheim (FN), Time Dependent Dielectric Breakdown (TDDB) and three test runs of the VG SbS are presented in this paper. Both technologies show good reliability figures to allow the use in the application. Trench technology shows higher robustness limits whereas the extrapolated reliability at the rated gate voltage is superior for the planar one.
Towards Making SiC ICs Durable and Accessible for Use in the Most Extreme Environments (Including Venus)
Authors: Neudeck Philip G. , Spry David J.
Published: July 2020

The prospects for beneficial application of integrated circuit (IC) capabilities in ambient environments above 450 °C have been significantly improved by recent long-term demonstrations of SiC chips and packaging by NASA Glenn Research Center. This invited paper reviews and updates development of durable SiC IC technology aspects relevant to engineering infusion into beneficial applications, including the first long-duration low-mass Venus lander missions
Experimental Study on Mitigation of Lifetime-Limiting Dielectric Cracking in Extreme Temperature 4H-SiC JFET Integrated Circuits
Authors: Spry David J. , Neudeck Philip G. , Chang Carl W.
Published: July 2020

While NASA Glenn Research Center’s “Generation 10” 4H-SiC Junction Field Effect Transistor (JFET) integrated circuits (ICs) have uniquely demonstrated 500 °C electrical operation for durations of over a year, this experimental work has also revealed that physical cracking of chip dielectric passivation layers ultimately limits extreme-environment operating lifetime [1-3]. The prevention of such dielectric passivation cracks should therefore improve IC high temperature durability and yield, leading to more beneficial technology adoption into aerospace, automotive, and energy systems. This report describes Generation 10.2, 11.1, and 11.2 die tested under unbiased and unpackaged accelerated age testing at 500 °C, 600 °C, 720 °C, and 800 °C in air-atmosphere ovens for 100-and 200-hour duration. Additional samples were separately subjected to 10 thermal cycles between the same high temperatures (with 10-hour high-temperature soak each cycle) and 50 °C. It is shown that having two stoichiometric Si3N4 layers in the interconnect dielectric stack substantially decreases the amount of dielectric cracking observed following these oven tests.
Microscopic Identification of Surface Steps on SiC by Density-Functional Calculations
Authors: Seino Kaori , Oshiyama Atsushi
Published: July 2020

We have performed density-functional calculations in order to clarify atomic structures and energetics of surface steps on SiC. The obtained energetics of distinct step types on vicinal 3C-SiC(111) surfaces which correspond to 4H- and 6H-SiC(0001) surfaces reveals the atom-scale reason for the experimental observation in the past that the step morphology is straight for the SiC(0001) surfaces inclined toward the 〈1-100〉 direction while it is meandering for the 〈11-20〉 inclined surfaces. The calculations clarify the rebonding between upper- and lower-terrace edge atoms, which is decisive for the energetics of the atomic steps.
Reducing On-Resistance for SiC Diodes by Thin Wafer and Laser Anneal Technology
Authors: Rusch Oleg , Hellinger Carsten , Moult Jonathan , Corcoran Yunji L. , Erlbacher Tobias
Published: July 2020

This work presents the influence of Thin Wafer und Laser Anneal Technology on the electrical performance of 4HSiC devices. Substrate thinning and backside ohmic contact formation via laser annealing were successfully applied to in-house designed and manufactured 6 A 650 V SiC diodes at IISB, improving its forward characteristics. The given devices exhibit an on-state voltage drop (VF) reduction from 1.78 V to 1.62 V at 6 A rated current while maintaining blocking capabilities of more than 1.1 kV with leakage currents less than 1 μA at 650 V nominal voltage. On-resistance (RON) was lowered by approx. 30 % to 90 mΩ and 60 % to 12 mΩ in Schottky and conductivity modulation state, respectively. Wafer thinning also allows reducing the influence of non-homogeneous distributed substrate doping concentrations, leading to a more narrow distribution of the forward characteristics of the devices across the wafer.
Non-Plasma Dry Etcher Design for 200 mm-Diameter Silicon Carbide Wafer
Authors: Kawasaki Ryohei , Irikura Kenta , Habuka Hitoshi , Takahashi Yoshinao , Kato Tomohisa
Published: July 2020

For improving the productivity of the semiconductor silicon carbide power devices, a very large diameter wafer process was studied, particularly for the non-plasma wafer etching using the chlorine trifluoride gas. Taking into account the motion of heavy gas, such as the chlorine trifluoride gas having the large molecular weight, the transport phenomena in the etching reactor were evaluated and designed using the computational fluid dynamics. The simple gas distributor design for a 200-mm-diameter wafer was evaluated in detail in order to uniformly spread the etchant gas over the wide wafer surface.
Chemical Behavior of Byproduct Layer in Exhaust Tube Formed by Silicon Carbide Epitaxial Growth in a System Using Chlorides
Authors: Mizushima Ichiro , Habuka Hitoshi
Published: July 2020

This study evaluated the chemical behavior of an oily byproduct which was formed in the exhaust tube during the silicon carbide epitaxial growth process using various precursors, such as silanes, chlorosilanes, propane, hydrogen chloride and hydrogen. Most of the precursors were spontaneously emitted from the oily byproduct, when the oily byproduct was kept under a nitrogen gas flow at atmospheric pressure and at room temperature. When the oily byproduct was exposed to 2-5 % chlorine trifluoride gas in ambient nitrogen at room temperature, various gaseous fluorides were produced, accompanying a slight temperature increase.
Direct Bonding of Diamond Substrate at Low Temperatures under Atmospheric Condition
Authors: Matsumae Takashi , Kurashima Yuichi , Umezawa Hitoshi , Takagi Hideki
Published: July 2020

A monocrystalline diamond substrate was bonded with a Si substrate employing a direct bonding technique. The diamond and Si surfaces were functionalized with hydroxyl (–OH) groups and subsequently bonded by the thermal dehydration reaction across the bonding interface. When a diamond (111) surface was treated with a mixture of H2SO4 and H2O2, it generated an atomic bond of C–O–Si with an oxygen-plasma-irradiated Si substrate. The bonding technique of diamond using the H2SO4/H2O2 mixture is expected to contribute to the future integration of diamond and semiconductor substrates because it allows low-temperature bonding in atmospheric air with negligible crystallinity damage.
SiC Natural and Artificial Superlattices for the Implementation of the Bloch Oscillation Process: A Comparative Analysis
Authors: Sankin Vladimir Ilich , Petrov Alexey G. , Shkrebiy Pavel P. , Kazarova Olga P. , Lebedev Alexander A.
Published: July 2020

Bloch oscillations in semiconductors have been studied for several decades. Oscillations were observed in artificial superlattices based on AlGaAs-GaAs proposed Esaki and Tsu, and the natural superlattice based on superstructures SiC. In this paper we considers some base properties of the SiC natural superlattices that are the ground for the Bloch oscillations existence in these materials and attract attention to the some main disadvantages of the artificial superlattices. The experimental detection of the Bloch oscillation-dependent physical effects in semiconductors has been an actual problem over decades.
Quantitative Characterization of Surface Polarity Dependence of Wetting Properties of V-Doped SiC Using a Novel Image Analysis Technique
Authors: Kim Jung Gon , Yoo Woo Sik , Kim Dae Sung , Lee Won Jae
Published: July 2020

Vanadium doped semi-insulating (SI) 6H-SiC {0001} substrates and their wetting properties were characterized using precisely dispensed de-ionized (DI) water drops. Radius, contact angle, width (chord), height and cap volume of a DI water drop on the SiC surface were quantitatively determined by analyzing sideview images of DI water drop in contact with SI 6H-SiC {0001} substrates using image processing software. The average of ten (10) contact angle measurements showed approximately 4 ° difference between the Si-face (48.48°) and the C-face (44.33º). Contact angle on the Si-face (0001) measured after native oxide removal showed significant decrease of contact angle, from 55° to 25° and recovered over time by room temperature oxidation in air. In contrast, contact angle on the C-face (000-1), measured after native oxide removal, showed significant increase of contact angle, from 40° to 54°, and continue to increase contact angle up to 71° after room temperature oxidation for 24 hours in air. Contact angle is found to be very sensitive to SiC surface polarity and specific surface conditions. Contact angle measurement, using image analysis techniques, can be applied as an in-line identification and surface condition characterization technique for SiC polytypes of specific surface polarities.
Interest of Using a Micro-Meter Spatial Resolution to Study SiC Semi-Conductor Devices by Optical Beam Induced Current (OBIC)
Authors: Sonneville Camille , Planson Dominique , Phung Luong Viet , Bevilacqua Pascal , Asllani Besar
Published: July 2020

In this paper we present a new test bench called micro-OBIC used to characterized wide band gap semi-conductor. Micro-OBIC allows to get an Optical Beam Induced Current (OBIC) signal with a microscopic spatial resolution. We used micro-OBIC to characterize peripheral protection such as MESA, JTE or JTE in high voltage SiC device.
Review and Detail Classification of Stacking Faults in 4H-SiC Epitaxial Layer by Mirror Projection Electron Microscopy
Authors: Ohira Kentaro , Isshiki Toshiyuki , Sako Hideki , Hasegawa Masaki , Kobayashi Kenji , Onuki Katsunori
Published: July 2020

Stacking faults (SFs) in 4H-SiC epitaxial wafers were inspected by using a mirror projection electron microscope (MPJ) [1, 2]. Dark and bright line contrasts of SFs in MPJ images represent surface morphology and crystal defects located in the epitaxial layer. Inspected SFs were classified into three types of SFs on the basis of the MPJ images. After classification, a cross section of each type of SF was observed by transmission electron microscopy (TEM) to verify the classification result. Complex SFs classified by MPJ images consisted of prismatic plane and basal plane SFs.
Enhancement of ODMR Contrasts of Silicon Vacancy in SiC by Thermal Treatment
Authors: Chiba Yoji , Yamazaki Yuichi , Sato Shin Ichiro , Makino Takahiro , Yamada Naoto , Satoh Takahiro , Hijikata Yasuto , Ohshima Takeshi
Published: July 2020

We demonstrated the enhancement of the optically detected magnetic resonance (ODMR) contrast of negatively charged silicon vacancy (VSi-) in SiC by thermal treatment. To create high density VSi-, Proton Beam Writing (PBW) was conducted. After an annealing at 600 °C, ODMR contrast showed the highest value in the investigated temperature range. At a fewer irradiation fluence, despite no significant change was observed in terms of VSi- PL intensity, the improvement of the ODMR contrast was observed. Considering defect energy levels and annealing behavior previously reported, it was deduced that the improvement of the ODMR contrast was caused by the reduction of other irradiation induced defect centers, such as EH1/EH3 centers.
Effects of Nitrogen Impurity Concentration on Nitrogen-Vacancy Center Formation in 4H-SiC
Authors: Narahara Takuma , Sato Shin Ichiro , Kojima Kazutoshi , Yamazaki Yuichi , Hijikata Yasuto , Ohshima Takeshi
Published: July 2020

Spin defects of which states can be manipulated in Silicon Carbide (SiC) have drawn considerable attention because of their applications to quantum technologies. The single negatively-charged pairs of VSi and nitrogen atom (N) on an adjacent C site (NCVSi- center) in SiC is suitable for them. This paper reports the formation of NCVSi- centers on 4H-SiC epilayers with different nitrogen concentrations using light/heavy ion irradiation and subsequent thermal annealing. The formation of NCVSi- centers is characterized by the near infrared photoluminescence (PL) spectroscopy. It is shown that the PL intensity from NCVSi- centers depends on the N concentration and the ion irradiation conditions. The PL intensity increases monotonically with increasing the N concentration when the N concentration is above 2.6×1016 cm-3, whereas no linear correlation between them does not appear below that N concentration. Although the PL intensity increases with increasing defects induced by ion irradiation, the PL quenching due to neighboring residual defects appear at above the areal vacancy concentration of 1017 vac/cm2 and the broad Raman scattering spectra originated from vibration modes of amorphized regions hinder the PL from NCVSi- centers at above 1018 vac/cm2. The formation mechanism and the charge state stability of NCVSi- centers are discussed based on the obtained results.
Near Infrared Photoluminescence of NCVSi- Centers in High-Purity Semi-Insulating 4H-SiC Irradiated with Energetic Charged Particles
Authors: Sato Shin Ichiro , Narahara Takuma , Onoda Shinobu , Yamazaki Yuichi , Hijikata Yasuto , Gibson Brant C. , Greentree Andrew , Ohshima Takeshi
Published: July 2020

This paper reports optical propertites of negatively charged NCVSi- centers in silicon carbide (a nitrogen substituting for a carbon atom adjacent to a silicon vacancy) whose emission wavlength is 1100-1500 nm at room temperature. High-purity semi-insulating (HPSI) 4H-SiCs are implanted with high energy N ion beams and subsequently thermally annealed to form NCVSi centers. We investigated a wide range of N ion implantation dose using a micro ion beam implantation technique and observed the photoluminescence intensity from the SiC-NV centers. We show that under conditions of heavy implantation, the excitation laser power excites residual defects and their fluorescences intereferes with the emission from the NCVSi- centers. These results allow us to clarify the requirements to optically detect isolated single NCVSi- centers at lightly implanted conditions.
The Effect of γ-Ray Irradiation on Optical Properties of Single Photon Sources in 4H-SiC MOSFET
Authors: Abe Yuta , Umeda Takahide , Okamoto Mitsuo , Harada Shinsuke , Yamazaki Yuichi , Ohshima Takeshi
Published: July 2020

We investigated the effects of γ-ray irradiation to single photon sources (SPSs) embedded in 4H-SiC metal-oxide-semiconductors field-effect transistors (MOSFETs). After the γ-ray irradiation, the number of SPSs was temporarily increased. However, the ratio of unstable SPSs was increased with increasing the radiation dose, and such unstable ones gradually disappeared. Finally, the density of the SPSs nearly recovered that before the irradiation. We discuss a possible explanation on these phenomena in terms of interactions between mobile hydrogen atoms and interface defects.
Progress in Bulk 4H SiC Crystal Growth for 150 mm Wafer Production
Authors: Manning Ian , Matsuda Yusuke , Chung Gilyong , Sanchez Edward , Dudley Michael , Ailihumaer Tuerxun , Raghothamachar Balaji
Published: July 2020

The thermoelastic stress, mechanical properties and defect content of bulk 4H n-type SiC crystals were investigated following adjustments to the PVT growth cell configuration that led to a 40% increase in growth rate. The resulting 150 mm wafers were compared with wafers produced from a control process in terms of wafer bow and warp, and dislocation density. Wafer shape was found to be comparable among the processes, indicating minimal impact on internal stress. Threading edge and threading screw dislocation densities increased and decreased, respectively, while basal plane dislocation densities were unaffected by the increase in growth rate. Loss of wafer planar stability was observed in certain cases. The elastic modulus was measured to be in the range of approximately 420-450 GPa for selected stable and unstable wafers, and was found to correspond to resistivity.
Photoluminescence Analysis of Individual Partial Dislocations in 4H-SiC Epilayers
Authors: Nishio Johji , Okada Aoi , Ota Chiharu , Kushibe Mitsuhiro
Published: July 2020

Configurations of the basal plane dislocations in 4H-SiC epitaxial layers are classified into two types, having typical combinations of ‘straight Si-core and straight C-core’ and ‘straight Si-core and curved C-core’ partial dislocations. The core species are determined by the photoluminescence images and observation of the moving Si-core partial dislocations by ultra-violet light illumination. Each partial dislocation was analyzed by photoluminescence spectroscopy. As the results, C-core partial dislocations have been found to have different peak wavelengths depending on the excitation power of the illumination. Also from the detailed analysis of individual partial dislocations, the curved C-core partial dislocations have been found to have different characters which may be originated from the mixture of different types of dislocations. It has been suggested that this model is possibly described by continuous connection of 30o and 90o dislocations which have different configurations of dangling bonds. The difference in photoluminescence peak wavelength might be explained by the structural difference.
Characterization and Reduction of Defects in 4H-SiC Substrate and Homo-Epitaxial Wafer
Authors: Yang Long , Zhao Li Xia , Wu Hui Wang , Liu Yafei , Ailihumaer Tuerxun , Raghothamachar Balaji , Dudley Michael
Published: July 2020

4H-SiC substrates and homo-epitaxial layers were obtained using the traditional methods of physical vapor transport and chemical vapor deposition. Defect morphology has been studied using both Synchrotron White Beam X-ray Topography and Monochromatic Beam X-ray Topography. Molten KOH etching method was adopted to further investigate the dislocation behavior mechanisms. Deflected dislocations were observed at the periphery regions in both substrate and epitaxial wafers. 3C polytypes and half loop arrays were observed in the 4H-SiC epitaxial wafer. It is also found that the majority of basal plane dislocations are converted to threading edge dislocations in the epitaxial wafer samples. The proportion of BPD to TED conversion depends on the surface step morphology and growth mode in epitaxial growth which in turn depends on the C/Si ratio. By the optimization of etching time prior to epitaxy and C/Si ratio, high-quality epitaxial wafers with extremely low basal plane dislocations densities (＜0.1 cm-2) was obtained.
Synchrotron X-Ray Topography Study on the Relationship between Local Basal Plane Bending and Basal Plane Dislocations in PVT-Grown 4H-SiC Substrate Wafers
Authors: Ailihumaer Tuerxun , Peng Hong Yu , Raghothamachar Balaji , Dudley Michael , Chung Gilyong , Manning Ian , Sanchez Edward
Published: July 2020

Synchrotron monochromatic beam X-ray topography (SMBXT) in grazing incidence geometry shows black and white contrast for basal plane dislocations (BPDs) with Burgers vectors of opposite signs as demonstrated using ray tracing simulations. The inhomogeneous distribution of these dislocations is associated with the concave/convex shape of the basal plane. Therefore, the distribution of these two BPD types were examined for several 6-inch diameter 4H-SiC substrates and the net BPD density distribution was used for evaluating the nature and magnitude of basal plane bending in these wafers. Results show different bending behaviors along the two radial directions - [110] and [100] directions, indicating the existence of non-isotropic bending. Linear mapping of the peak shift of the 0008 reflection along the two directions was carried out using HRXRD to correlate with the results from the SMBXT measurements. Basal-plane-tilt angle calculated using the net BPD density derived from SMBXT shows a good correlation with those obtained from HRXRD measurements, which further confirmed that bending in basal plane is caused by the non-uniform distribution of BPDs. Regions of severe bending were found to be associated with both large tilt angles (95% black contrast BPDs to 5% white contrast BPDs) and abrupt changes in a and c lattice parameters i.e. local strain.
Dislocations Analysis on Implanted (p-Type and n-Type) 4H-SiC Epi-Layer by KOH Molten Etching
Authors: Anzalone Ruggero , Severino Andrea , Piluso Nicolo , Coffa Salvo
Published: July 2020

In this work the effect of the ion implantation on the dislocations structure of the 4H-SiC epilayer after the KOH etching has been investigated. The study was conducted using both Aluminum (Al) and Phosphorous (P) species for p-type and n-type, respectively. The ion implantations of Al and P were carried out at different energies (30–200 keV) to achieve 300 nm thick acceptor box profiles with a concentration of about 1020 at/cm3. The implanted samples were annealed at high temperatures. With sequential sacrificial and stopping layer both species has been implanted on the same sample. Morphological charaterization of the samples (optical microscope and SEM) shown different structural modification of the dislocations (experically TED) after the KOH etching of the samples.
Investigation of Dislocation Behavior at the Early Stage of PVT-Grown 4H-SiC Crystals
Authors: Ailihumaer Tuerxun , Raghothamachar Balaji , Dudley Michael , Chung Gilyong , Manning Ian , Sanchez Edward
Published: July 2020

Dislocation behavior during the early stages of physical vapor transport (PVT) growth of 6-inch diameter 4H-SiC crystals has been investigated by synchrotron monochromatic beam X-ray topography (SMBXT) in conjunction with ray tracing simulations of dislocation images. Our studies reveal that most of the TSDs/TMDs are replicated into the newly grown layer while most TEDs are generated by either nucleation in pairs at the growth interface or by redirection of BPDs in the seed crystal. Most BPDs in the newly grown layer are of screw type with and this has been verified by comparison with ray tracing simulated images. TEDs with same and opposite sign of Burgers vector are found to be deflected on to the same basal plane by the overgrowth of macro-steps and they glide in the same and opposite directions respectively. TMDs deflected on to the basal plane by macro-steps get dissociated into c and a components, with the a segment undergoing glide to form V-shaped configurations.
Crystalline Quality Evaluation of SiC p/n Column Layers Formed by Trench-Filling-Epitaxial Growth
Authors: Adachi Kohei , Kosugi Ryoji , Ji Shi Yang , Kawada Yasuyuki , Fujisawa Hiroyuki , Tomohisa Shingo , Miura Naruhisa , Yonezawa Yoshiyuki , Okumura Hajime
Published: July 2020

We evaluated crystalline quality of SiC p/n column layers over 20 μm thickness formed by trench-filling-epitaxial growth. Although threading dislocation density of trench-filling-epitaxial layer is almost same as flat n-type epitaxial layer, threading dislocations are localized in only trench-filled p-columns. We consider that threading dislocations migrated toward p-columns around trench bottom during trench-filling-epitaxial growth.
Investigation of Dislocations Inducing Leakage Current on SiC Junction Barrier Schottky Diode by Two-Photon-Excited Band-Edge Photoluminescence
Authors: Nakanishi Yosuke , Noguchi Tomoaki , Nakamura Takuyo , Ikegami Masaaki , Kobayashi Kazuo , Konishi Kazuya , Ebihara Kohei
Published: July 2020

Tilt angles of threading dislocations (TDs) which induce leakage of current on SiC junction barrier schottky diodes (SiC-JBSs) were investigated by two-photon-excited photoluminescence (2PPL) and transmission electron microscopy (TEM). Observation of leakage spots measured by atomic force microscopy (AFM) revealed that pit-like structures were certainly formed but the depths were considerably shallow, indicating that influence of local electric field due to the structures was negligible on our SiC-JBSs. It became clear that tilt angles of the TDs inducing leakage were relatively larger than about 11° by 2PPL and that the TD was the threading mixed dislocation by TEM.
Impact of Threading Dislocations Detected by KOH Etching on 4H-SiC 650 V MOSFET Device Failure after Reliability Test
Authors: Severino Andrea , Anzalone Ruggero , Piluso Nicolo , Vitanza Elisa , Carbone Beatrice , Russo Alfio , Coffa Salvo
Published: July 2020

In this study, the correlation between the Emission Microscopy (Em.Mi.) related to the failure site of the 4H-SiC 650V MOSFET devices after reliability test and epitaxial dislocation defects is presented. Devices failed at the High-Temperature Reverse Bias (HTRB) test were considered. Device layers have been stripped out by chemical wet etching and etched in a high temperature KOH solution to characterize defects emerging at the SiC surface. This approach was used to correlate failure emission spots with underlying structure of the material. KOH etching process on delayered devices was performed at 500°C for 10 minutes and then analysis by optical microscopy and SEM was carried out for defect classification and correlation with failure location.
Nano- and Micro-Scale Simulations of Ge/3C-SiC and Ge/4H-SiC NN-Heterojunction Diodes
Authors: Rashid Muhammad Haroon , Koel Ants , Rang Toomas
Published: July 2020

During the last decade, silicon carbide (SiC) and its heterostructures with other semiconductors have gained a significant importance for wide range of electronics applications. These structures are highly suitable for high frequency and high power applications in extremely high temperature environments. SiC exists in more than 200 different polycrystalline forms, called polytypes. Among these 200 types, the most prominent polytypes with exceptional physical and electrical attributes are 3C-SiC, 4H-SiC and 6H-SiC. Heterostructures of these SiC polytypes with other conventional semiconductors (like Si, Ge) can give rise to interesting electronic characteristics. In this article, Germanium (Ge) has been used to make heterostructures with 3C-SiC and 4H-SiC using a novel technique called diffusion welding. Microscale and nanoscale simulations of nn-heterojunction of Ge/3C-SiC and Ge/4H-SiC have been done. Microscale devices have been simulated with a commercially available semiconductor device simulator tool called Silvaco TCAD. Whereas nanoscale devices have been simulated with QuantumWise Atomistix Toolkit (ATK) software package. Current-voltage (IV) curves of all simulated devices have been calculated and compared. In nanoscale device, the effects of defects on IV-characteristics due to non-ideal bonding (lattice misplacement) at heterojunction interface have been analyzed. Our simulation results reveal that the proposed heterostructure devices with diffusion welding of wafers are theoretically possible. These simulations are the preparations of our near future physical experiments targeted to fabricate SiC based heterostructure devices using diffusion bonding technique.