bluuebunny/crossref_metadata_2025 huggingface dataset:
A rua no Brasil em questão (etnográfica)
Authors: Frehse Fraya
Published: July 2015

Quais os rendimentos teóricos e metodológicos que, para o debate das ciências sociais sobre a rua no Brasil, oferece uma etnografia das regras de interação social de pedestres específicos, que denomino não-transeuntes, no centro histórico da São Paulo de hoje? Após caracterizar a rua do cenário acadêmico nacional, cabe confrontá-la com as regularidades simbólicas apreendidas “autoetnograficamente” na copresença física de pedestres que permaneceram com regularidade notadamente na Praça da Sé no primeiro semestre de 2013. O vigor empírico de viração e autointegração pessoais dos não-transeuntes em três situações interacionais comigo (nosso primeiro contato, a apresentação deles a mim e nosso convívio posterior) remete à rua como espaço público de pessoalidade moral. A rua dos não-transeuntes da Praça da Sé é mediação de práticas sociais que evidenciam de modo sui generis os dilemas metodológicos do etnógrafo em situações de interação social “focadamente desfocada” entre pessoas morais.
Transportes públicos e representações sobre mobilidade social: possíveis percepções a partir do Rio de Janeiro e de Buenos Aires
Authors: Pires Lênin
Published: July 2015

O artigo propõe uma reflexão sobre possíveis percepções a respeito da utilização de transportes públicos e representações de cidadania. A abordagem utiliza dados construídos em etnografias realizadas nas Regiões Metropolitanas de Buenos Aires, na Argentina, e Rio de Janeiro, no Brasil. Ao utilizarem os serviços de transportes, os atores sociais, em uma dada sociedade, parecem relacionar dimensões de espaço e tempo, construindo e/ou conjugando formas específicas de classificação dos espaços sociais compartilhados na Região Metropolitana. O artigo explora as noções de mobilidade, circuito, trajetória, entre outros, com o intuito de sinalizar para as possíveis vinculações entre previsibilidade no exercício de direitos e imprevisibilidade das trajetórias sociais.
Como a Antropologia pode contribuir para a pesquisa jurídica? Um desafio metodológico
Authors: Lima Roberto Kant de , Baptista Bárbara Gomes Lupetti
Published: July 2015

A importância de articular Direito e Antropologia – embora reconhecida por instituições como o MEC, que inseriu a Antropologia Jurídica no currículo da graduação em Direito, e pelo CNPq, que a elenca como subárea do Direito – ainda não está de fato legitimada pelos operadores jurídicos. O fazer antropológico pressupõe a relativização de verdades consagradas, enquanto o fazer jurídico através delas se reproduz, sendo este contraste metodológico um significativo obstáculo ao diálogo destes campos. Exercitar a aproximação destes saberes é um desafio não apenas para o Direito, mas também para a Antropologia, pois ambas as áreas não pautam as suas agendas a partir de discussões comuns. Este artigo destaca a importância de uma metodologia própria da antropologia, a etnografia, de base empírica e calcada no trabalho de campo e na perspectiva comparativa contrastiva, para o desenvolvimento da pesquisa na área do Direito. Demonstraremos que essa metodologia é extremamente valiosa para a compreensão do campo jurídico, como também explicitaremos alguns dos obstáculos que causam os ruídos de comunicação desses campos. A metodologia utilizada para a construção dos dados é fruto da observação participante dos autores, que são formados em Direito e têm experiência acadêmica e profissional na área da Antropologia Jurídica.
O dizível e o indizível: narrativas de dor e violência em cárceres brasileiros
Authors: Taets Adriana Rezende Faria
Published: July 2015

Este artigo debruça-se sobre narrativas do cárcere. A partir da análise das narrativas sobre a trajetória profissional de uma agente prisional em particular, é possível pensar em diversos aspectos que envolvem a experiência dentro do cárcere, dentre eles, a dor, a memória e a violência. Desde os conceitos trabalhados por Halbwachs sobre memória e Veena Das acerca da experiência violenta e o trabalho do tempo, o artigo pretende abordar a elaboração de narrativas de situações em que a dor e a violência não apenas se mostram presentes, mas principalmente organizam a estrutura narrativa. Tendo como base uma pesquisa etnográfica realizada com agentes prisionais femininas no estado de São Paulo, o artigo discute a maneira como a experiência no cárcere pode ser compreendida através das histórias construídas no intuito de compartilhar a dor vivenciada ali dentro.
Reglamento para el regimiento, servicio y gobierno del cuerpo de pardos de San Juan Bautista de Mazatlán, 1792
Authors: Llanes Espinoza Wilfrido
Published: July 2015

El documento “Reglamento para el regimiento, servicio y gobierno del cuerpo de pardos de San Juan Bautista de Mazatlán, 1792”, se inscribe dentro de la serie de reglamentos formados en la Nueva España a partir de mediados del siglo XVIII, como parte de la reestructuración del cuerpo militar del virreinato.En ocho títulos, el documento da cuenta de los requerimientos para pertenecer al cuerpo de milicias de Mazatlán, el sueldo que percibirían, los servicios a prestar, los beneficios conseguidos; también contiene un listado de sus integrantes al momento de conformarse en 1792, entre otros aspectos. El reglamento se liga a un contexto bien reconocible, las exigencias que presentaba la defensa de las costas novohispanas, particularmente las del Pacífico sur de Sinaloa, ante el acecho de las potencias europeas (Francia, Rusia e Inglaterra) y las insurrecciones de los grupos nativos de la región.
Are Taxes a Determinant Factor in Earnings Management Behavior?
Authors: Flores Eduardo , Sampaio Joelson Oliveira , Sales George
Published: July 2015

Unequal tax rules between economic sectors can stimulate the practice of earnings management. Our purpose is therefore to determine whether the enforcement of these laws have created incentives for earnings management in Brazil. To test the hypothesis, we selected a sample-data composed by Brazilian insurance companies, since this sector suffered a considerable increase in the income-taxes rate in 2008, moving the global rate from 34% to 40%. The utilization of this group was motivated because according to Brazilian tax regulatory system, technical accruals from insurance companies are considers deductible from income taxes. The results showed a significant relationship between the increased tax rates and the measure of the technical accruals, showing evidence of earnings management behavior in this industry specifically in the period in which the tax-rate was increased for this group of companies.
Research Methods, Data, and Analytics
Authors: Gibbs William J. , Bernas Ronan S.
Published: July 2015

Media organizations deliver news services online employing various design techniques and technologies to make services useful, usable, and effective for news consumers. How people use news services, their perceptions of them, and how their design impacts the user experience (UX) is an important area of study. In this chapter, the authors examine service design, UX, and related research methodologies and their importance for online news. Additionally, they report on a study that examined how the type of news provider (TV versus newspaper) and associated services affected user behavior and perception of the user experience. Participants perceived news websites differently based on the type of news provider and their interactions with services differed based on type of provider. The findings have implication for the UX research, specifically UX related to online news.
Shaping Content Strategies with User Analytics and Identities
Authors: Syed Tricia
Published: July 2015

User data has become the foundation of many businesses. The ability to increase the breadth and depth of user data to analyze trends is now the roadmap for information companies – providing direction for new business, content strategy, print to digital shifts and overall retention and engagement. In this chapter, the author will explore user identity and the three key core data buckets – Profile, Activity, and Behavioral – that define how to decipher audience members and their ‘user records.' The chapter will specifically showcase how user identity shapes editorial strategy, marketing messaging and drives revenue. It will look at the impact specific technologies are having on what data can be captured as well as the complexities around data capture in general – standardization, preservation, storage, relational data opportunities and data optimization.
Big Data, Text Mining, and News Content
Authors: Cheney Debora
Published: July 2015

Mining the natural language text of news content has great potential for academic researchers seeking to understand and visualize patterns and relationships buried within everyday news coverage and content. Mining news can help researchers across many disciplines understand the impact of news, biases in news coverage, and language usage. It can also help them detect unknown patterns in news coverage. However, researchers must understand the challenges of using news text for text-mining-based research. Many challenges are inherent in the news form, including the complexity of the news environment; changing patterns of news consumption and distribution; growing use of social media; and the use of visual and audio information. Additional challenges relate to determining if the news content is available in a digital format, access and license restriction on use of the news text, and how complete and completely searchable the news text really is. This chapter explores these challenges and the impact they may have on how researchers gain access to news text, and methodologies used.
Research Methodologies, Data Collection, and Analysis at MailChimp
Authors: Bernstein Gregg , Wolfram-Hvass Laurissa
Published: July 2015

Research plays a crucial role in understanding and improving the user experience. In this case study, members of software company MailChimp's Research team explain the company's data collection, analysis, and communication methodologies. Using methods that include customer interviews, big data, reports, and short films, the team moves through the research process, beginning with research questions and concluding with actionable insights.
Spreading the News
Authors: Baron Robert J.
Published: July 2015

This chapter is concerned with the process of “spreading the news” through social media. It suggests a method of rhetorical analysis that focuses less attention on the content of news productions and more attention on analyzing how audience members might make use of the news. This transition of focus from content to audience use should lead news producers to see the value of content that engages with audiences and enables audience members to engage in the sharing and spreading of news content. The purpose of this chapter is twofold: 1) to help journalists design content that engages their audiences in the process of spreading the news in ways that can go far beyond the reach of traditional news formats and 2) to provide journalism scholars with a means of understanding the ways in which audiences and the news media interact in social media-rich communication environments.
Visualizing Social Network Influence
Authors: Lipschultz Jeremy Harris
Published: July 2015

Billions of social media users communicate via Web and mobile platforms. A variety of measurement tools may be used to advance research methodologies in the study of computer-mediated communication (CMC). Social networking sites (SNS), such as Twitter, allow researchers to conduct exploratory data scraping and create visual mapping of possible relationships between social network accounts. The nature of the visualization depends upon the number of accounts within the social network, the amount of communication activity, the direction of specific communication, the amplification of messages across the network and other factors. A major challenge of this research method is disclosure and verification of individuals operating online identities. Additionally, most free research tools fail to disclose algorithms for generating scores and ranks. The purpose of this chapter is to explain how individual position, or centrality, is one reflection among many in the measurement of social network influence.
Transformational Content and Relationships
Authors: Schwartz Stuart
Published: July 2015

This chapter outlines the trend toward research within news organizations based upon big data and the increasing emphasis of growth-oriented companies on promoting a positive and passionate User Experience (UX). It discusses the implications of digital research techniques developed by successful technology and consumer merchandising organizations, and links the 24/7 nature of digital research methodologies to the development of more user-responsive and successful news organizations. A journalistic organization that wants to grow in the digital age must revamp its operations to take advantage of the continuous big data research cycle. This means creating a feedback loop from the organization to the information consumer and back, viewing journalism as content to be shaped to the UX through constant modification and change based on growing sets of user behavior and preference data.
Microwave Heating Assisted Biorefinery of Biomass
Authors: Farag Sherif , Chaouki Jamal
Published: July 2015

This chapter debates the potential of the biorefinery of biomass using microwave heating. First, the essential information regarding electromagnetic radiation is explained and the pros and cons of microwave heating versus conventional heating, especially in the thermochemical treatment of biomass, are discussed. Different methodologies for predicting and measuring the temperature gradient within a material subjected to electromagnetic waves are demonstrated. The chapter summarizes the key conclusions of various investigations regarding the effects of microwave heating on chemical reactions and presents how electromagnetic radiation can assist the biorefinery of biomass. Finally, the issues and limitations regarding scaling-up microwave heating are elucidated, along with possible solutions to these problems.
Energy and Exergy Analysis on Gasification Processes
Authors: Gómez Edgardo Olivares , Neves Renato Cruz , Magalhães de Medeiros Elisa , Rezende Mylene Cristina Alves Ferreira
Published: July 2015

In recent years, attention has focused on exergy analysis, a type of thermodynamic analysis which is an important tool for the efficiency assessment and the processes optimization when dealing with energy conversion and, particularly, thermochemical processes such as gasification. Thus, this chapter aims to introduce the fundamental concepts of energy and exergy and describe the energy and exergy evaluation tools, elucidating its importance for calculations applied to gasification processes. A case study was performed to show the proposal of energy and exergy analysis. Therefore, a single global gasification chemical reaction was used to represent the gasification process. This analysis can provide a tool to assess and develop models, simulations, calculations, and to optimize real gasification processes. Information and experiences covered in this chapter help to be put into perspective the technology, research and overcoming of challenges.
Biomass Processing Routes for Production of Raw Materials with High Added Value
Authors: Filho Rubens Maciel , Tovar Laura Plazas , Ardila Yurany Camacho , Figueroa Jaiver Efrén Jaimes , Maciel Maria Regina Wolf
Published: July 2015

In this chapter sugarcane bagasse may be submitted to a biological route in which the technologies used to obtain lignocellulosic ethanol (2nd generation ethanol) from lignocellulosic materials involve pre-treatment and the hydrolysis of the polysaccharides in the biomass into fermentable sugars for subsequent fermentation. Taking into consideration the use of sugarcane bagasse as a raw material for 2nd generation ethanol, the acid hydrolysis / pretreatment of sugarcane bagasse could be more feasible that others, and must be evaluated in this context. On the other hand, from biomass is possible to obtain products with high added value and energy, mainly by the use of thermochemical processes (e.g. pyrolysis and gasification) and biochemical processes (e.g., fermentation and anaerobic digestion). However, the products obtained from the thermochemical processes can be used as raw material for biochemical processes which multiplies the quantity of products to be obtained from biomass.
Sustainability, Business Models, and Techno-Economic Analysis of Biomass Pyrolysis Technologies
Authors: Garcia-Peréz Manuel , Garcia-Nunez Jesus Alberto , Pelaez-Samaniego Manuel Raul , Kruger Chad Eugene , Fuchs Mark Raymond , Flora Gloria Eileen
Published: July 2015

The objective of this chapter is to review and discuss sustainability and techno-economic criteria to integrate pyrolysis, biochar activation, and bio-oil refining into sustainable business models. Several business models such as the production of biochar with heat recovery and bio-oil refining are discussed. Cost data needed by engineering practitioners to conduct enterprise-level financial analyses of different biomass pyrolysis economy models are presented. This chapter also reviews life cycle assessments of pyrolysis business models. If the feedstock used is produced sustainably and if the pyrolysis vapors are used for bio-oil or heat production, both, the production of biochar through slow pyrolysis and its use as a soil amendment to sequester carbon, and the production and refining of fast pyrolysis oils to produce transportation fuels could have a positive environmental impact.
Cloud Computing SaaS Paradigm for Efficient Modelling of Solar Features and Activities
Authors: Hayajneh Sofyan Mohammad
Published: July 2015

Cloud computing is one of the promising approaches that add a lot of revolutionary contribution to power many real life applications. More power is gained by the ability of such approach to handle different programming languages that were previously handled by one standalone platform (normal computer) only. There are many different solar activities that originate from the Sun and may extremely impact daily life. The existence of these activities is highly associated to different solar features that can be modelled using the huge number of available solar images. There are many different agencies that analyse these images to visualize these activities and features. In this paper, a new cloud-based service that allows efficient and remote access for the users and specialists in the Solar imaging field is proposed without overwhelming the users with any software installation, maintenance, and not requiring them to upgrade to new releases of this service. It is aimed to provide such a service in real time using cloud computing capabilities while saving the cost of procuring resources.
Multi-Cloud Data Management using Shamir's Secret Sharing and Quantum Byzantine Agreement Schemes
Authors: AlZain Mohammed A. , Li Alice S. , Soh Ben , Pardede Eric
Published: July 2015

Cloud computing is a phenomenal distributed computing paradigm that provides flexible, low-cost on-demand data management to businesses. However, this so-called outsourcing of computing resources causes business data security and privacy concerns. Although various methods have been proposed to deal with these concerns, none of these relates to multi-clouds. This paper presents a practical data management model in a public and private multi-cloud environment. The proposed model BFT-MCDB incorporates Shamir's Secret Sharing approach and Quantum Byzantine Agreement protocol to improve trustworthiness and security of business data storage, without compromising performance. The performance evaluation is carried out using a cloud computing simulator called CloudSim. The experimental results show significantly better performance in terms of data storage and data retrieval compared to other common cloud cryptographic based models. The performance evaluation based on CloudSim experiments demonstrates the feasibility of the proposed multi-cloud data management model.
Common Method Bias in PLS-SEM
Authors: Kock Ned
Published: July 2015

The author discusses common method bias in the context of structural equation modeling employing the partial least squares method (PLS-SEM). Two datasets were created through a Monte Carlo simulation to illustrate the discussion: one contaminated by common method bias, and the other not contaminated. A practical approach is presented for the identification of common method bias based on variance inflation factors generated via a full collinearity test. The author's discussion builds on an illustrative model in the field of e-collaboration, with outputs generated by the software WarpPLS. They demonstrate that the full collinearity test is successful in the identification of common method bias with a model that nevertheless passes standard convergent and discriminant validity assessment criteria based on a confirmation factor analysis.
Shared Practices in Articulating and Sharing Rationale
Authors: Xiao Lu , Carroll John M.
Published: July 2015

This paper reports a classroom study in which group learners brainstormed ideas in virtual group space and justified their ideas through articulating their rationales in the shared rationale space. The investigation focused on the learners' practices of articulating and sharing rationales. The results suggest that group members would brainstorm the ideas and generate rationales to justify the ideas before reading the others' ideas and rationales. Also, the members in general brainstormed all the ideas first and then elaborated the rationales to justify the ideas; and grouped the shared rationales according to their authors. The group members' reasoning styles were examined by using Rhetorical Structure Theory to analyze the shared rationales. It was found that similar reasoning styles existed across the groups. Additionally, the group context seemed to have affected the members' strategies of using contextual and additional information to justify their ideas. Several design implications are presented to support the practices of articulating and sharing rationales in virtual group workspace. The authors also articulate how their work contributes to other research areas such as project management, crowdsourcing, and online deliberation. Based on their study, the authors argue for a rationale-based knowledge management approach to complex collective activities in the online environment.
Meta-Analysis of Virtual Teams
Authors: Bhat Swati Kaul , Alavi Shirin , Ahuja Vandana
Published: July 2015

Growth in technology has brought the world economy on a single platform which has deeply impacted the working pattern of organizations. It is the increase in usage of internet technology which facilitated the process of bringing individuals across the globe together and forming teams to help them achieve defined tasks. This change in corporate scenarios and shrinking of location barriers has led to the formation of special kinds of teams: virtual teams. The challenge before organizations is to effectively manage these teams because of their negligible physical contact. This research paper attempts to collect and analyze the literature available on the role played by trust in building an effective virtual team. A review of literature presented in the paper deals with the origin and working of virtual teams. This manuscript explores how trust has emerged as an important factor for the appropriate functioning of a virtual team and helps managers and employees in understanding the role of trust in the success of their team. The findings of the study are directed towards benefitting organizations who are involved in planning, developing, and administering programs for the smooth functioning of employees using a virtual paradigm to enhance employee productivity.
Overview of the Mechanisms of Drag Reduction by Means of Flexible Surfaces
Authors: Gu Yun Qing , Dai Dong Shun , Mou Jie Gang , Zheng Shui Hua , Jiang Lan Fang , Sun Zhuang Zhi , Wang Evan
Published: July 2015

The research of drag reduction technique have the advantages of saving energy and improving utilization rate, which behaves a tremendous value in economy and military, hence it is a hot issue for researchers all the time. Merging together with the method of bionic drag reduction, drag reduction mechanisms with flexible surface have realized its function by imitating the elastic characteristics of dolphin skin and using the interaction between flexible materials and boundary layer fluid. Development status of drag reduction technique with flexible surface was analysed, and its mechanisms were reviewed from two aspects of delayed transition and disturbance on boundary layer. In addition, drag reduction mechanisms with flexible surface were explored in terms of changing the structure in the boundary layer, moreover, its development tendency was prospected.
A Comprehensive Review of the Biomimetic Applications of Ionic Polymer Metal Composite
Authors: Haq Mazhar Ul , Gang Zhao , Muhammad Waqas Hafiz
Published: July 2015

Bio-inspiration focuses on translating the evolutionary successes of natural species into engineering systems that mimic the geometry, function, and performance of the natural system. In this paper we present a latest comprehensive review of ionic polymer metal composite (IPMC) biomedical and biomimetic applications. IPMC is becoming an increasingly popular material among scholars, engineers and scientists due to its inherent properties of low activation voltage, large bending strain, flexibility, softness, suitable response time which make them a strong candidate to be applied as artificial muscle in biomimetic land and underwater applications. Among the diversity of electro active polymers (EAPs), recently developed IPMCs are good candidates for use in bio-related application because of their biocompatibility. Several recently reported IPMC biomimetic applications have been reported in this paper. The applications of IPMC have been growing due to progression in its manufacturing techniques, development of more accurate response models and control techniques, and recently more sophisticated IPMC actuator applications have been performed. This indicates that the IPMC actuators hold potential for more sophisticated and controlled applications in fields of biomedical and biomimetic. Extensive references are provided for more indepth explanation.
Forward Kinematic Analysis of IPMC Actuated Three Link Mechanism for Fin Actuation of Fish Like Micro Device
Authors: Haq Mazhar Ul , Gang Zhao , Usman Shaban , Ur Rehman Anees , Aftab S.M.
Published: July 2015

IPMC is becoming an increasingly popular material among scholars, engineers and scientists due to its inherent properties of low activation voltage, large bending strain, flexibility, softness, suitable response time which make them a strong candidate to be applied as artificial muscle in biomimetic land and underwater applications. The applications of IPMC have been growing due to progression in its manufacturing techniques, development of more accurate response models and control techniques, and recently more sophisticated IPMC actuator applications have been performed. In this paper, a new application of IPMC is proposed to actuate aileron fins of a micro scanning device towed underwater by a surface vessel to control its depth and to stabilize it against roll motion that can mimic pectoral fins of fish that steer them up and down by changing their angle of rotation and their dorsal fins that keep them upright against roll. Same is applicable for autonomous underwater vehicles. Secondly, a three link mechanism is presented to actuate aileron fin through IPMC actuator. Three dimensional model of the mechanism is developed in Pro-Engineer CAD software tool and its kinematic analysis is performed. Thirdly, forward kinematic model of proposed mechanism, based on geometric coordinate, is presented. Lastly, results of kinematic analysis of proposed mechanism are compared to that of model to verify its design and kinematics. Encouraging results decoy the research team to manufacture the mechanism and to perform experiments for its practical application.
Variation of Entrance Length Effect on EHD Gas Pump Performance
Authors: Birhane Yilma Tadesse , Lin Sheam Chyun , Huang Te Yen
Published: July 2015

The effects of entrance length on performance and flow characteristic of EHD gas pump has been experimentally examined in this study. A 61.8mm-in-diameter EHD gas pump with eight evenly spaced emitting electrodes and flush mounted on the tube inner wall is used for this investigation. The experiment is conducted for two applied voltages 19 kV and 20kV with positive polarity. Several (L/D) ratios are used aiming at picking the appropriate length to achieve highest ionic discharge and maximum pump performance. Results show that the lowest (L/D) ratio gives the best pump performance with highest discharge managed.
Optimization of the Surface Roughness and Superficial Hardness Improvement Using the Hybrid Grey-Based Taguchi Method for the Small Ball-Burnishing Process of STAVAX
Authors: Banh Quoc Nguyen , Shiou Fang Jung
Published: July 2015

This study aims to optimize the small ball-burnishing process parameters in order to simultaneously improve the surface roughness and superficial surface hardness of the STAVAX material. A newly developed load cell embedded double spring mechanism burnishing tool was designed and fabricated. By utilizing the hybrid grey-based Taguchi method with principal component analysis (PCA) and entropy measurement the optimal process condition was the combination of the burnishing force at 10 N, the step-over at 6 μm, the number of passes at 3 times, the grease for lubricant, and the burnishing speed at 500 mm/min. The burnishing force, step-over, and the number of passes were found to have the main effects on the burnished surfaces among the five chosen control factors. The burnished surface of STAVAX material under the optimal condition was improved from Ra 0.85 to Ra 0.079 for average surface roughness, and from 67.3 HR30N to 72.7 HR30N in term of superficial hardness.
An Ultrasonic Motor Using Thrust Bearing with Dimple Structure on the Friction Surface
Authors: Ishii Takaaki , Yamawaki Hiroki , Ohuchi Hidetoshi
Published: July 2015

An ultrasonic motor using thrust ball bearing with dimple structure on the friction surface has been proposed. The bearing balls are rotated by the friction force caused by the ultrasonic vibration of the stator, and transfer torque to the rotor. The dimple structure on the sliding surface can hold the ball position and rotate the balls and the rotor without a retainer. The newly proposed motor can avoid the friction loss between balls and the retainer. The balls of 2.4 mm in radius are used and the radii of the curvature of the dimples of 2.0 mm and 3.0 mm are used in this research. The radius difference changes the contact condition between the balls and the dimple structure. Fundamental motor characteristics are measured and discussed.
CAD Modeling and Optimization of the Optimal Geometric Features of a Microdrill
Authors: Bogale Teshome Mulatie , Shiou Fang Jung , Tang Geo Ry
Published: July 2015

The objective of this paper is to construct a CAD model and to determine the optimal geometric features of a 0.1 mm diameter of microdrill. The CAD model was constructed using Pro/Engineer software by determining the flute of a microdrill mathematically. The cross section comparison between the model and fabricated microdrill was carried out by cutting at different lengths, and the results of the web thickness of the model and the fabricated microdrill were approximately the same. Hence, the CAD Modeling of a microdrill based on determining the flute mathematically by considering both setting angle and profile of a grinding wheel was feasible. The optimal geometric features of a microdrill have been determined by carrying out optimization of the stress/displacement analysis using Pro/Mechanica software so that the maximum stress Von Mises of the microdrill was minimal.
Structural Investigation of Si Quantum Dots Grown by CVD on AlN/Si(111) and 3C-SiC/Si(100) Epilayers
Authors: Dagher Roy , Khazaka Rami , Vézian Stephane , Teissiere Monique , Michon Adrien , Zielinski Marcin , Chassagne Thierry , Cordier Yvon , Portail Marc
Published: July 2015

Structural investigations of Si quantum dots (QDs) grown by CVD on two different heterostructures: AlN/Si (111) and 3C-SiC/Si (100) are conducted. The Si QDs have been grown using silane as precursor, diluted in hydrogen, at fixed temperature and pressure (830°C - 800mbar). High densities of dots can be obtained (up to 1011 cm-2) with typical heights below 10nm. The kinetic of deposition lets suppose the presence of an initial wetting layer before the dots formation. Different durations are required for nucleating dots on AlN and 3C-SiC. Si QDs on AlN present a luminescence band which can be attributed to quantum confinement.
Novel Poly-Si/GaN Vertical Heterojunction Diode
Authors: Emori Kenta , Marui Toshiharu , Saito Yuji , Ni Wei , Nakajima Yasushi , Hayashi Tetsuya , Hoshi Masakatsu
Published: July 2015

We previously reported a unipolar mode p+-polycrystalline silicon (poly-Si)/4H-SiC heterojunction diode (SiC-HJD) [1-3]. In this work, we demonstrate a poly-Si/GaN vertical unipolar heterojunction diode (GaN-HJD) based on numerical simulation and experimental results. The GaN-HJD is expected to control the electrical characteristics of both Schottky action with a p-type poly-Si and ohmic action with an n-type poly-Si. We investigated the detailed physics of the GaN-HJD between p+ Si and n+ Si by numerical simulation. The GaN-HJD was also fabricated with p+-type polycrystalline silicon on an n--type epitaxial layer on bulk GaN substrates. The measured barrier height of the GaN-HJD was 0.79 eV and the ideality factor was 1.10.
Controlling Planar Defects in 3C-SiC: Ways to Wake it up as a Practical Semiconductor
Authors: Nagasawa Hiroyoki , Gurunathan Ramya , Suemitsu Maki
Published: July 2015

Eelectrically active defects in 3C–SiC are investigated by considering the structures and interactions of planar defects. An anti-phase boundary (APB) largely degrades the blocking property of semiconductor devices due to its semimetallic nature. Although APBs can be eliminated by orienting the specific polar face of 3C-SiC along a particular direction, stacking faults (SFs) cannot be eliminated due to Shockley-type partial dislocation glide. SFs with Shockley-type partial dislocations form a trapezoidal plate which expands the Si-terminated surface with increasing 3C-SiC thickness. Although the density of SFs can be reduced by counter termination, specific cross-junctions between a pair of counter SFs forms a forest dislocation, and this is regarded as an electrically active defect. This paper proposes an effective way to suppress the forest dislocations and APBs which nucleate during 3C-SiC growth.
Effect of C/Si Ratio and Nitrogen Doping on 4H-SiC Epitaxial Growth Using Dichlorosilane Precursor
Authors: Song Hai Zheng , Chandrashekhar M.V.S. , Sudarshan T.S.
Published: July 2015

Application of dichlorosilane (DCS) in 4H-SiC epitaxial growth on 4° off-cut substrates has been studied. The effect of C/Si ratio and N2 gas flow rate on epilayer properties is investigated in detail. It is found that the C/Si ratio has a significant influence on the growth rate, epilayer surface roughness (step-bunching), conversion of basal plane dislocations (BPDs), and generation of morphological defects and in-grown stacking faults. A wide range of doping concentration from p- to n+ can be controlled in DCS growth. High quality 4° off-cut SiC epilayers are achieved for C/Si=1.3 – 1.8. Addition of N2 has no obvious influence on growth rate and defect densities. The BPD conversion greater than 99.8% is achieved independent of N doping without any pretreatment.
Influence of Growth Pressure and Addition of HCl Gas on Growth Rate of 4H-SiC Epitaxy
Authors: Tanaka Takanori , Kawabata Naoyuki , Mitani Yoichiro , Sakai Masashi , Tomita Nobuyuki , Tarutani Masayoshi , Kuroiwa Takeharu , Toyoda Yoshihiko , Imaizumi Masayuki , Sumitani Hiroaki , Yamakawa Satoshi
Published: July 2015

The reduction of the growth pressure was demonstrated to have the same effect as the addition of chloride-containing gas on preventing the Si nucleation and the epitaxy with high growth rate (>50 μm/h) was achieved by using the decreasing pressure condition in a horizontal CVD reactor without chloride-containing gas. The quality of a 30-μm-thick epilayer grown with 40 μm/h was also investigated. Downfall and triangle defect density in the layer was as low as 0.16 /cm2, indicating that a high quality epitaxial wafer can be easily obtained under the condition with high throughput in the sinple CVD system.
The Role of Chlorine during High Growth Rate Epitaxy
Authors: Karhu Robin , Booker Ian , Hassan Jawad , Ivanov Ivan , Janzén Erik
Published: July 2015

The influence of chlorine has been investigated for high growth rates of 4H-SiC epilayers on 4o off-cut substrates. Samples were grown at a growth rate of approximately 50 and 100 μm/h and various Cl/Si ratios. The growth rate, net doping concentration and charge carrier lifetime have been studied as a function of Cl/Si ratio. This study shows some indications that a high Cl concentration in the growth cell leads to less availability of Si during the growth process.
Uniformity Improvement in Carrier Concentration on 150 mm Diameter C-Face Epitaxial Growth of 4H-SiC
Authors: Nishio Johji , Asamizu Hirokuni , Kudou Chiaki , Ito Sachiko , Masumoto Keiko , Tamura Kentaro , Kojima Kazutoshi , Ohno Toshiyuki
Published: July 2015

The guidelines necessary to improve the n-type doping uniformity on C-face epitaxial growth of 4H-SiC have been examined as far as the practical throughput is maintained, e.g. 3×150 mm wafers with the growth rate higher than 20 μm/h. The flow-channel enlargement was carried out and the effect was estimated by temperature distribution estimation performed by hydrogen etching. Also, effective C/Si was simulated with the temperature distribution obtained from the hydrogen etching experiments. As a result, positional agreement was found between the region where carrier concentration begins to increase and the drastic drop in temperature and the effective C/Si ratio.
Characterization of Comet-Shaped Defects on C-Face 4H-SiC Epitaxial Wafers
Authors: Yamashita Tamotsu , Matsuhata Hirofumi , Sekiguchi Takashi , Momose Kenji , Osawa Hiroshi , Kitabatake Makoto
Published: July 2015

The crystallographic structure of comet-shaped defects observed on C-face 4H-SiC epitaxial film was investigated. The comet-shaped defects consist of head and tail part. The tail part shows symmetrical shape with respect to the (1-100) plane in cross section and narrowing along the step-flow direction. The tail part consists of four 3C domains with characteristic twin boundaries of Σ3 and Σ27. The head part consists of 3C poly-crystalline grains formed during epitaxial film growth and its formation is triggered by 3C-SiC particle contamination.
Influence of Epi-Layer Growth Pits on SiC Device Characteristics
Authors: Kudou Chiaki , Asamizu Hirokuni , Tamura Kentaro , Nishio Johji , Masumoto Keiko , Kojima Kazutoshi , Ohno Toshiyuki
Published: July 2015

Homoepitaxial layers with different growth pit density were grown on 4H-SiC Si-face substrates by changing C/Si ratio, and the influence of the growth pit density on Schottky barrier diodes and metal-oxide-semiconductor capacitors were investigated. Even though there were many growth pits on the epi-layer, growth pit density did not affect the leakage current of Schottky barrier diodes and lifetime of constant current time dependent dielectric breakdown. By analyzing the growth pit shape, the aspect ratio of the growth pit was considered to be the key factor to the leakage current of the Schottky barrier diodes and the lifetime of metal-oxide-semiconductor capacitors.
Control of Interface Shape by Non-Axisymmetric Solution Convection in Top-Seeded Solution Growth of SiC Crystal
Authors: Koike Daiki , Umezaki Tomonori , Murayama Kenta , Aoyagi Kenta , Harada Shunta , Tagawa M. , Sakai Takenobu , Ujihara Toru
Published: July 2015

We achieved the convex growth interface shape in top-seeded solution growth of SiC applying non-axisymmetric solution convection induced by non-axisymmetric temperature distribution. The detailed solution flow, temperature distribution and carbon concentration distribution were calculated by 3-dimensional numerical analysis. In the present case, the solution flow below the crystal was unidirectional and the supersaturation was increased along the solution flow direction. By the rotation of the crystal in the unidirectional flow and the temperature distribution, we successfully obtained the crystal with the convex growth interface shape.
3C-SiC Crystal on Sapphire by Solution Growth Method
Authors: Shibata Kenji , Harada Shunta , Ujihara Toru
Published: July 2015

We realized the growth of 3C-SiC crystal on sapphire by solution growth method. The carbon deposition on a sapphire substrate before growth is the key point for this technology. This carbon layer plays a role to protect the dissolution of sapphire by Si solvent. Single crystal of 3C-SiC was grown on the whole surface of the sapphire substrate. Surprisingly, the 3C-SiC layer did not directly grown on the sapphire substrate. The single crystal 3C-SiC layer formed by the reaction between the deposited carbon and the Si wafer that is a solvent material below the melting point of silicon during heating process before the growth. The 3C-SiC grew on the 3C-SiC layer. In this process, the deposited carbon play another important role.
3C-SiC Polycrystalline Films on Si for Photovoltaic Applications
Authors: Privitera Stefania , Brancato Vincenza , Spadaro Donatella , Anzalone Ruggero , Alberti Alessandra , La Via Francesco
Published: July 2015

The electrical and optical properties of n-doped polycrystalline 3C-SiC films grown on 6 inches Si wafers have been investigated as a function of precursor gases, deposition temperature and C/Si ratio. The Si/SiC interface has been optimized, eliminating the voids formation through a double temperature step process and by introducing a thin not intentionally doped layer. Films with high surface roughness, favourable for light trapping in photovoltaic applications, and with resistivity around 20 mOhm cm have been obtained for C/Si ratio close to 1. Simple solar cells have been also manufactured and proved the functionality of poly 3C-SiC/Si heterojunction solar cell. Increased quantum efficiency in the range 300-500 nm has been observed, compared to amorphous Si, making poly 3C-SiC heterojunction solar cells interesting for high temperature applications or water splitting.
High Quality 3C-SiC (111) Epitaxial Layer on Si (110) Substrate by Using Si2Cl6+C3H8
Authors: Lee Hee Tae , Lee Hee Jun , Park Mi Seon , Jang Yeon Suk , Lee Won Jae , Kim Jung Gon , Nishino Shigehiro
Published: July 2015

The 3C-SiC (111) layer has been grown on Si (110) substrate by using hexachloro-disilane (HCDS) and propane. The propane flow rate was controlled in the carbonization step and the growth step for obtaining SiC layer with high crystal quality. The high quality epitaxial 3C-SiC (111) layer was successfully grown at growth temperature of 1280°C and lower propane flow rate condition. Grown 3C-SiC epitaxial layers were systematically analyzed by an optical microscope, Raman spectroscopy, FE-SEM and XRD
Effect of Nitrogen Dilution in the Optical Properties of Amorphous SiC Thin Films
Authors: Montañez Liz , Guerra Jorge A. , de Zela Francisco , Winnaker Albrecht , Weingärtner Roland
Published: July 2015

The effect of the nitrogen dilution on the optical and vibrational properties of amorphous silicon carbide (a-SiC) and silicon oxycarbide (a-SiCO) layers have been studied. The films were prepared by radio frequency (rf) reactive magnetron sputtering using an atmosphere mixture of argon (Ar) and nitrogen (N2). The oxygen (O2) was incorporated according to the base pressure used of each deposition process. The optical and vibrational properties of the films were characterized by means of UV/VIS transmittance measurements and Fourier transform infrared spectroscopy (FTIR), respectively. A relationship between the variation of the optical bandgap and the increase or quench of vibrational modes is established. This analysis reveals that the increase of nitrogen in both host matrices a-SiC and a-SiCO induced the formation of C=N and C N bonds thus reducing the bandgap of the material.
Comparative Study of n-Type 4H-SiC: Raman vs Photoluminescence Spectroscopy
Authors: Kwasnicki Pawel , Arvinte Roxana , Peyre Hervé , Zielinski Marcin , Juillaguet Sandrine
Published: July 2015

This paper presents a comparative optical and vibrational spectroscopy study of diversely n-type 4H-SiC epilayers. It is shown that in order to determine the nitrogen doping in a wide range (1016 up to few 1019cm-3) the two techniques are complementary. Moreover only the LTPL provides the information about the compensation and nature of the dopant species.
Applying Chemometrics for Analysis of SiC Raman Imaging Data
Authors: Milikofu Olga , Kozu Tomomi , Batten Tim
Published: July 2015

New ultrafast Raman imaging methods allow high definition data to be collected from a whole wafer scale down to individual defects in 2D and 3D, on a time scale suitable for routine quality control. On the other hand, just one hour of data collection can result in datasets containing 105~106 spectra, and attempts to manually analyze such big data with traditional univariate methods can take days, without guarantee that all important information is revealed. Such problem can be easily overcome with fast and automated multivariate analysis methods. Here we introduce the techniques and demonstrate applications to SiC.
Optical Characterization of p-Type 4H-SiC Epilayers
Authors: Liaugaudas Gediminas , Dargis Donatas , Kwasnicki Pawel , Peyre Hervé , Arvinte Roxana , Juillaguet Sandrine , Zielinski Marcin , Jarašiūnas Kęstutis
Published: July 2015

A series of aluminium doped (from 2×1016 to 8×1019 cm-3) 4H-SiC epitaxial layers were mainly studied by Low Temperature Photoluminescence and time-resolved optical pump-probe techniques to determine the concentration of aluminium, its activation ratio, the doping related carrier lifetime, hole mobility and excess carrier diffusion length.
Photoelectrical Parameters of a PVT Grown Bulk 15R-SiC Crystal at Different Stages of Growth
Authors: Liaugaudas Gediminas , Dargis Donatas , Jarašiūnas Kęstutis , Tsavdaris Nikolaos , Sarigiannidou Eirini , Chaussende Didier
Published: July 2015

The electronic quality of a Physical Vapour Transport (PVT) grown 15R-SiC crystal at different stages of growth was assessed by time-resolved optical pump-probe techniques. The measured differential transmittivity (DT) kinetics for the layers corresponding to the initial, middle and final stages of growth revealed clear differences in the decay of the DT signal, indicating a decreasing concentration of traps at the later stages of the crystal growth. The estimated trap concentration in the initial layer was NT ≈ 1019 cm-3, while it decreased down to less than 2×1018 cm-3 in the top layer. The injection dependence of the diffusion coefficient at room temperature confirmed the gradual decrease of NT in the layers corresponding to later stages of growth. Accordingly, the bipolar diffusion coefficient in the middle and the top layer was Da ≈ 2 cm2/s, while Da = 0.9 cm2/s was measured in the layer closest to the seed.