bluuebunny/crossref_metadata_2025 huggingface dataset:
Karakteristik Jaringan Secara Histologi dari Strain Rumput Laut (Kappaphycus alvarezii) yang Terinfeksi Penyakit Ice-Ice
Authors: Maulani Resi Kumala , Achmad Marlina , Latama Gunarto
Published: July 2019

Salah satu yang menyebabkan kegagalan budidaya rumput laut Kappaphycus alvarezii  yaitu terserangnya penyakitice – ice . Penyakit ice-ice merupakan penyakit yang umum terjadi pada rumput laut kappaphycus  dengan gejalaterjadinya pemutihan pada bagian thallus  dan penyakit ini dapat menyebabkan kematian massal pada produksirumput laut kappaphycus alvarezii . Salah satu cara yang dapat dilakukan untuk menganalisa bagian thallus  rumputlaut Kappaphycus alvarezii  yaitu uji histopatologi. Penelitian ini bertujuan untuk mengetahui perubahan bentuksel pada kondisi jaringan thallus  rumput laut K.alvarezii  yang terserang penyakit ice- ice  menggunakan metodehistopatologi. Pengambilan sampel rumput laut yang digunakan jenis Kappaphycus alvarezii  varietas coklat danhijau dengan 1 titik masing – masing varietas. Sampel rumput laut terdiri atas 2 sampel yaitu bagian thallus  yangterserang penyakit ice-ice  dan bagian thallus  tanpa gejala ice-ice . Sampel berumur 15 hari. Sampel yang dipilihuntuk pemeriksaan, dipotong setebal 0,5 - 1 cm. Sampel dimasukkan kedalam botol sampel untuk difiksasi ± 1minggu, yang berisi formalin 10%.Tahapan pembuatan preparat histopatologi terdiri atas fiksaksi, dehidrasi,clearing , impregnasi , embedding , cutting , staining , dan pemeriksaan dibawah mikroskop. Penelitian ini dianalisissecara dekskriptif kualitatif dengan melakukan pengamatan gambar histopatologi pada jaringan rumput laut K.alvarezii . Jaringan thallus  yang yang terserang penyakit ice-ice  mengalami perubahan bentuk sel, bagian lapisanluar terlihat tidak utuh, hancur, sehingga mengalami kematian sel dan bagian korteks dalam dinding sel terlihattidak teratur dan renggang, tidak terbentuk bulat atau lonjong, sebagian sel mengecil. Jaringan thallus  yang tidaknormal mengalami gejala Hipoplastik (terhambatnya atau terhentinya pertumbuhan sel) dan Nekrotik (kematiansel).Kata kunci : Kappaphycus alvarezii, penyakit ice – ice, Histopatologi, Hipoplastik, Nekrotik
Use of Dissolved Glucose on Cultured Media on the Survival Rate, Growth Rate and Stress Resistance of Saline Tilapia Larvae (Oreochromis niloticus)
Authors: Imran Muh. Ali , Maharani Yuni , Marding Hardiati , Dahlia Andi , Karim Muh. Yusri
Published: July 2019

Saline tilapia fish is a result of technology engineering technique that is tolerant with brackish waters and sea with salinity ≥ 20 ppt. The main problem in the development of saline tilapia is the availability of seeds because the resulting synthesis is still low. One effort to overcome the problem of low tilapia salinity this is by providing dissolved organic material such as glucose. Glucose plays an important role as a source of energy for animals including tilapia. The aim of this research is to determine the optimum dose of dissolved glucose to the survival and growth of salt tilapia larvae (Oreochromis niloticus). The research was conducted from March to May 2017 at Brackish Water Aquaculture (BPBAP) Takalar, South Sulawesi. The research container using 25 L plastic volume basin amounted to 15 pieces. The test animals used were 7-day saline tilapia larvae of 0.03 gram sized for 20 days. The glucose used is pure glucose in powder form. The study was designed using a complete randomized design consisting of 5 treatments and each having 3 replications. The five treatments are 0, 50, 100, 150, 200 ppm per day added to the once-daily research container that is the morning. The result of variance analysis showed that soluble glucose administration had significant effect (p <0.01) on the synthesis and growth rate of saline tilapia fish. The highest survival rates and growth rates were achieved at 100 ppm doses of 94.44% and 14.93% / day respectively, while the lowest at doses of 0 ppm were 74.81% and 11.85% / day respectively.Keywords: glucose, salin tilapia, survival, growth rate
Effectivity of mulberry leaf extract on stimulating ekdisteroid hemolimph content and molting of mud crab (Scylla olivacea)
Authors: Fujaya Yushinta , Trijuno Dody Dharmawan , Haryati Haryati , Hasnidar Hasnidar , Rusdi Muhammad , Usman Zainal
Published: July 2019

This study aims to study the performance of phytoecdisteroids from mulberry leaves in molting stimulating of mangrove crabs. The research was carried out at the Research and Development Center for Aquaculture at the Faculty of Marine Sciences and Fisheries at Hasanuddin University, located in Bojo Village, Mallusetasi District, Barru Regency, South Sulawesi Province. Mangrove crabs (Scylla olivacea) weighing 45-55 g and carapace widths 60-65 mm were used as test animals. There were five doses of mulberry leaf extract applied through feed, namely: A) 1.1 mg / g feed, B) 1.9 mg / g feed, C) 2.7 mg / g feed, D) 3.5 mg / g feed. Crabs were kept individually in plastic boxes that are floated above the surface of the pond. During rearing, crabs are fed 3% dry fish per day which has been enriched with mulberry leaf extract. The parameters observed were ecdysteroid compounds contained in mulberry leaf extract, ecdysteroid content in hemolymph before and after application of mulberry leaf extract, and molting percentage. Identification of the ekdisteroid compounds contained in mulberry leaf extract was carried out using Thin Layer Chromatography (TLC) and Measurement of the content of ecdysteroids in crab hemolymh was carried out using Ultra Fast Liquid Chromatography (UFLC).  The results showed that the 3.5 mg dose of mulberry leaf extract / g feed gave the highest increase in ecdysteroid hemolymph, which was approximately 1760 ekdisteroid per mL hemolimph, while the dose of 1.1 mg / g feed only provided an increase of 100 ng ekdisteroid per mL hemolymph. The higher the dose of mulberry leaf extract in the feed, the higher the increase in the concentration of hemolymph ecdysteroids, but the high concentration of ecdystoid in the hemolymph does not guarantee molting.  The optimal dose of mulberry leaf extract in the feed stimulating molting was 2.4 mg / g of feed.Keywords: mulberry, phytoecdysteroid, molting, crab, aquaculture
Scientific Goals and In-orbit Performance of the High-energy Particle Detector on Board the CSES
Authors: Picozza P. , Battiston R. , Ambrosi G. , Bartocci S. , Basara L. , Burger W. J. , Campana D. , Carfora L. , Casolino M. , Castellini G. , Cipollone P. , Conti L. , Contin A. , De Donato C. , De Santis C. , Follega F. M. , Guandalini C. , Ionica M. , Iuppa R. , Laurenti G. , Lazzizzera I. , Lolli M. , Manea C. , Marcelli L. , Martucci M. , Masciantonio G. , Mergé M. , Osteria G. , Pacini L. , Palma F. , Palmonari F. , Panico B. , Parmentier A. , Patrizii L. , Perfetto F. , Piersanti M. , Pozzato M. , Puel M. , Rashevskaya I. , Ricci E. , Ricci M. , Ricciarini S. , Scotti V. , Sotgiu A. , Sparvoli R. , Spataro B. , Vitale V. , Zuccon P. , Zoffoli S.
Published: July 2019

The China Seismo-Electromagnetic Satellite (CSES) aims to monitor electromagnetic, particle, and plasma perturbations in the iono-magnetosphere and inner Van Allen radiation belts originated by electromagnetic sources external and internal to the geomagnetic cavity, cosmic rays, and solar events. In particular, the objective of the space mission is to investigate lithosphere–atmosphere–ionosphere coupling mechanisms (including the effects of lightning, earthquakes, volcanoes, and artificial electromagnetic emissions) that induce perturbations of the top side of the ionosphere and lower boundary of the radiation belts. To this purpose, the mission has been conceived to take advantage of a multi-instrument payload comprising nine detectors for the measurement of electromagnetic field components, plasma parameters, and energetic particles, as well as X-ray flux. The Italian team participating in the CSES mission has built one of these devices, the High-Energy Particle Detector (HEPD), for high-precision observations of electrons, protons, and light nuclei. During its trip along the orbit, and thanks to the large set of detectors operated on board, CSES completely monitors the Earth, acting as an excellent instrument for space weather. The satellite was launched on 2018 February 2, with an expected life span of 5 yr. This article describes the CSES mission with a particular focus on the HEPD apparatus and its in-flight performance.
Déterminants du recours au répit pour les proches aidants de malades atteints de démence
Authors: Bannerot Frédéric , Leocadie Marie-Conception , Rothan-Tondeur Monique
Published: July 2019

Introduction : L’évolution démographique et le vieillissement de la population concourent à l’augmentation des maladies d’Alzheimer ou apparentées. Encouragé par les politiques de santé, le maintien à domicile des patients souffrant de ces pathologies est souvent dépendant de la contribution de proches aidants. L’exigence de ce rôle peut fragiliser les personnes concernées et favoriser chez elles l’apparition d’un sentiment de fardeau nécessitant le recours à des périodes de répit. Étude ancillaire d’un programme de recherche mené sur l’agglomération de Genève, notre travail vise à caractériser les déterminants d’un recours aux dispositifs de répit pour les proches aidants de patients atteints de démence, Méthode : Recherche qualitative, menée par la méthode de focus groupes, auprès des proches aidants de patients atteints de démence. Trois focus groupes ont été menés, avec 12 participants dans les agglomérations de Genève (Suisse) et Rouen (France). Résultats : Notre étude relève la concomitance de l’évolution des troubles de la personne aidée et l’émergence d’un sentiment de fardeau chez l’aidant, lié à la durée et l’intensité de l’aide prodiguée. Nos résultats permettent de distinguer les déterminants d’un recours aux dispositifs de répit qui dépendent de l’aidant ou des institutions et d’en proposer une modélisation. Conclusion : Les dispositifs de répit doivent bénéficier d’une coordination et s’adapter aux exigences des bénéficiaires, en termes de format et de qualité, afin d’en faciliter le recours aux populations les plus fragiles et d’éviter qu’il ne soit trop tardif.
“Women are those who lose their sense of shame”: resistance and fulfilment of gender expectations in dissident initiatives in a rural district of Argentina
Authors: Kunin Johana
Published: July 2019

The present article analyzes how and why women are those who “lose their sense of shame” to coordinate and take part in social interventions and dissident activities based on the notion of “participation” in the peripheries of La Laguna, a rural agro city in the province of Buenos Aires, Argentina. Supported by extensive ethnographic fieldwork, this article asserts that an emic worldview in which women are associated with mothers and mothers with care enables women in La Laguna to withstand stigmatization and oppose hegemonic views on agricultural production and health in a district where social protest is nearly completely absent. The political maternalisms that we describe let women “take care” of “society”, the “neighborhood”, their “children” and even themselves. When doing so, they put themselves at risk, but such social risk is much less than it would be for men, who, with identities linked to notions of “real work” and “discretion”, do not have time for “stupidities”. Women are, thus, doubly able to both resist and fulfill gender expectations.
Persecución y re-significación de lo popular y femenino en el mercado de la salud en Chile y Argentina 1850‑1900
Authors: Durán Manuel
Published: July 2019

Durante el siglo XIX en Chile y Argentina, se instituyó un discurso médico positivista, regulando los modelos de género y clase. Fortaleciendo un paradigma científico y masculino. Ya organizados gremial y académicamente, el sector médico patriarcal inició una depuración del “mercado de la salud”, oponiéndose al ejercicio popular y femenino de la salud: meicas, parteras y sanadores. Por otra parte el sector médico profesional constituyó una imagen de la “naturaleza femenina” en términos de inestabilidad física y psicológicamente, incompatible con el ejercicio de un oficio científico. Estos “imaginarios” se instalaron en la mentalidad colectiva, constituyendo un discurso naturalizado. En este contexto las primeras médicos debieron re-significar nuevos ámbitos de acción médica, bajo una “política de los cuidados”, generando nuevos discursos y disciplinas profesionales.
Récits non naturels, narratologie non naturelle : apports, problèmes et perspectives
Authors: Patron Sylvie
Published: July 2019

L’étude des récits non naturels (unnatural narratives), ou narratologie non naturelle (unnatural narratology), est l’un des derniers courants apparus au sein de la narratologie postclassique. Cette approche parait novatrice et prometteuse car elle rejoint plusieurs préoccupations actuelles associées à la théorie, à l’analyse et à l’interprétation des récits de fiction. Elle est aussi intensément discutée dans les milieux narratologiques. Loin d’être une approche unifiée, la narratologie non naturelle se compose de différentes tendances, basées sur des définitions légèrement différentes des récits non naturels, prônant des approches parfois très différentes, voire opposées, de ces récits. La narratologie non naturelle peut déjà se prévaloir d’apports importants dans l’étude des récits non naturels ou des éléments non naturels dans les récits, généralement négligés dans la ou les narratologies établies. Une étude un peu approfondie fait cependant apparaitre certains problèmes. Un exemple significatif est donné à la fin de l’article.
La trace écrite scolaire : un récit ?
Authors: Promonet Aurore
Published: July 2019

L’écriture scolaire ordinairement et quotidiennement pratiquée en France est appelée trace écrite. Elle se constitue d’écrits variés que l’enseignant décide de faire archiver dans les cahiers, carnets des élèves. Ces écrits constituent un corpus scolaire varié, faiblement prescrit et peu étudié. Le cahier relève d’une tradition scolaire qui alimente une partie du patrimoine des musées de l’éducation. Ce support ne change guère au fil des années. On y lit l’activité scolaire, la vie de la classe et la réussite des élèves. Le cahier peut se constituer en récit de vie, en récit de parcours scolaire ; il peut surtout soutenir l’élève dans son développement personnel comme sujet didactique au sein des disciplines scolaires. Cet article propose de le montrer à partir d’analyse de journaux d’apprentissages produits en dernières années d’école élémentaire.
Aux marges de la fiction sérielle télévisuelle : sémio-pragmatique de la shortcom familiale
Authors: Delaporte Chloé
Published: July 2019

Cet article examine la relation entretenue par le sous-genre de la shortcom familiale avec la fiction sérielle télévisuelle, à partir d’un cadre théorique qui n’a pas été pensé pour l’analyse des séries télévisées : la sémio-pragmatique. Alors que les shortcoms familiales Scènes de ménages (M6, 2009-), Nos chers voisins (TF1, 2012-2017) ou Parents mode d’emploi (France 2, 2013-) se présentent comme des formes fictionnelles, leur analyse sémio-pragmatique révèle une hybridité énonciative de nature à solliciter de la part des publics d’autres modes de lecture que la seule lecture fictionnalisante.
Exploring Collocations with The Prime Machine
Authors: Jeaco Stephen
Published: July 2019

One of the greatest impacts of corpus linguistics on language teaching has been in the recognition of the importance of collocation. A very influential guide for language teachers with regard to teaching collocation has been the Lexical Approach. Activities pointing students to rich collocational information in monolingual dictionaries, in texts and specifically in collocation dictionaries provided ways for language learners to engage with collocation information: to notice, to remember and to acquire. In recent years, there has been a growing interest in Data Driven Learning and new tools are now available to allow students to access collocation information from corpora for themselves. After introducing some pedagogic considerations, this article presents some of the features of The Prime Machine which were developed to support DDL activities focussed on collocation.
Modeling an Intrusion Detection System Based on Adaptive Immunology
Authors: Alaparthy Vishwa , Morgera Salvatore D.
Published: July 2019

Network security has always has been an area of priority and extensive research. Recent years have seen a considerable growth in experimenting with biologically inspired techniques. This is a consequence of the authors increased understanding of living systems and the application of that understanding to machines and software. The mounting complexity of telecommunications networks and the need for increasing levels of security have been the driving factors. The human body can act as a great role model for its unique abilities in protecting itself from external entities owing to its diverse complexities. Many abnormalities in the human body are similar to that of the attacks in wireless sensor networks (WSN). This article presents the basic ideas that can help modelling a system to counter the attacks on a WSN by monitoring parameters such as energy, frequency of data transfer, data sent and received. This is implemented by exploiting an immune concept called danger theory, which aggregates the anomalies based on the weights of the anomalous parameters. The objective is to design a cooperative intrusion detection system (IDS) based on danger theory.
Software Defect Prediction Using Hybrid Distribution Base Balance Instance Selection and Radial Basis Function Classifier
Authors: Panda Mrutyunjaya
Published: July 2019

Software is an important part of human life and with the rapid development of software engineering the demands for software to be reliable with low defects is increasingly pressing. The building of a software defect prediction model is proposed in this article by using various software metrics with publicly available historical software defect datasets collected from several projects. Such a prediction model can enable the software engineers to take proactive actions in enhancing software quality from the early stages of the software development cycle. This article introduces a hybrid classification method (DBBRBF) by combining distribution base balance (DBB) based instance selection and radial basis function (RBF) neural network classifier to obtain the best prediction compared to the existing research. The experimental results with post-hoc statistical significance tests shows the effectiveness of the proposed approach.
Caching Resource Sharing for Network Slicing in 5G Core Network
Authors: Jia Qingmin , Xie RenChao , Huang Tao , Liu Jiang , Liu Yunjie
Published: July 2019

Network slicing has been considered a promising technology in next generation mobile networks (5G), which can create virtual networks and provide customized service on demand. Most existing works on network slicing mainly focus on virtualization technology, and have not considered in-network caching well. However, in-network caching, as the one of the key technologies for information-centric networking (ICN), has been considered as a significant approach in 5G network to cope with the traffic explosion and network challenges. In this article, the authors jointly consider in-network caching combining with network slicing. They propose an efficient caching resource sharing scheme for network slicing in 5G core network, aiming at solving the problem of how to efficiently share the limited physical caching resource of Infrastructure Provider (InP) among multiple network slices. In addition, from the perspective of network slicing, the authors formulate caching resource sharing problem as a non-cooperative game, and propose an iteration algorithm based on caching resource updating to obtain the Nash Equilibrium solution. Simulation results show that the proposed algorithm has good convergence performance, and illustrate the effectiveness of the proposed scheme.
A Study of CVD Growth Parameters to Fill 50-μm-Deep 4H-SiC Trenches
Authors: Ji Shi Yang , Kosugi Ryoji , Kojima Kazutoshi , Adachi Kohei , Kawada Yasuyuki , Mochizuki Kazuhiro , Nagata Akiyo , Matsukawa Yasuko , Yonezawa Yoshiyuki , Yoshida Sadafumi , Okumura Hajime
Published: July 2019

By inspecting the CVD growth parameters, such as the flow rates of HCl and H2 carrier gases, the pressure and the C/Si ratio, the trench filling in a high-rate mode with a high growth rate on the bottom and a relatively low growth rate on the mesa top was carried out. 4H-SiC trenches with the depths of 48 and 55 μm have been completely filled at the rates of 6.2 and 5.5 μm/h, respectively.
Characterization of Near-Interface Traps at Dielectric/SiC Interfaces Using CCDLTS
Authors: Jayawardhena Isanka , Jayawardena Asanka , Jiao Chun Kun , Morisette Dallas , Dhar Sarit
Published: July 2019

Charge trapping at 4H-SiC/dielectric interfaces in 4H-SiC MOS capacitors has been investigated using constant capacitance deep level transient spectroscopy (CCDLTS). The experiments were focused on further understanding of the following aspects related to 4H-SiC/SiO2 interfaces: (i) Origin of near interface oxide traps (NITs), (ii) Effect of interfacial impurity/passivation methods and (iii) Characterization of near-interface oxide traps for different SiC wafer orientations. For the (0001) Si-face 4H-SiC/ SiO2 interface, two types of NITs are typically detected by CCDLTS, named ‘O1’ and ‘O2’ traps with emission activation energies of about 0.15±0.05 eV and 0.39±0.1 eV respectively below the 4H-SiC conduction band. Based on comparison with previous ab initio calculations, the physical identities of these defects have been suggested to be carbon dimers substituted for O dimers (‘O1’) and interstitial silicon atoms (‘O2’) in the near interfacial SiO2 respectively. In this work, it is shown for the first time that such traps are not observed for 4H-SiC/ Al2O3 interfaces, proving that these traps are inherent to the near-interfacial SiO2. In addition, the summary of CCDLTS results for Si-face with different interface trap passivation methods are included in this study. Finally, a comparison is presented for NO annealed (0001) Si-face, (11-20) a-face and (000-1) C-face interfaces that highlight the difference of CCDLTS signatures for the different crystal faces.
Sub-nm-Scale Depth Profiling of Nitrogen in NO- and N2-Annealed SiO2/4H-SiC(0001) Structures
Authors: Moges Kidist , Sometani Mitsuru , Hosoi Takuji , Shimura Takayoshi , Harada Shinsuke , Watanabe Heiji
Published: July 2019

We demonstrated an x-ray photoelectron spectroscopy (XPS)-based technique to reveal the detailed nitrogen profile in nitrided SiO2/4H-SiC structures with sub-nanometer-scale-resolution. In this work, nitric oxide (NO)- and pure nitrogen (N2)-annealed SiO2/4H-SiC(0001) structures were characterized. The measured results of NO-annealed samples with various annealing duration indicate that preferential nitridation just at the SiO2/SiC interfaces (~0.3 nm) proceeds in the initial stage of NO annealing and a longer duration leads to the distribution of nitrogen in the bulk SiO2 within few nanometers of the interface. The high-temperature N2 annealing was found to induce not only SiO2/SiC interface nitridation similarly to NO annealing but also SiO2 surface nitridation.
SiO2/SiC MOSFETs Interface Traps Probed by Nanoscale Analyses and Transient Current and Capacitance Measurements
Authors: Fiorenza Patrick , Giannazzo Filippo , Saggio Mario , Roccaforte Fabrizio
Published: July 2019

This paper aims to give an overview on some relevant aspects of the characterization of the SiO2/4H-SiC interface, considering the properties of this system both at the interface and inside the insulator. Nanoscale scanning probe microscopy (SPM) techniques were used to get insights on the homogeneity of the SiO2/SiC interface electrical properties upon metal-oxide-semiconductor (MOS) processing. On the other hand, capacitance and current measurements as a function of time were employed to investigate trapping states in MOS structures in the SiO2/4H-SiC system. In particular, time-dependent gate current measurements gave information on the near interface oxide traps (NIOTs) present inside the SiO2 layer. The impact of the observed trapping phenomena on SiO2/SiC metal oxide semiconductor field effect transistors (MOSFETs) operation is discussed.
Impact of Pit Defects on the Initial Electrical Characteristics of Planar-MOSFET Devices
Authors: Guo Ling , Kamei Koji , Momose Kenji , Osawa Hiroshi
Published: July 2019

In this paper, the effects of various defects on the initial electrical characteristics of planar-MOSFET devices were investigated. The measurement results revealed that some pit defects that resulted from the fabrication process were as harmful as traditional killer defects in Schottky barrier diode devices. These pit defects could be observed and distinguished by photoluminescence imaging technology. It is necessary to inspect wafers during fabrication—especially before the film deposition process, when the pit defects are easily overlaid and hidden.
Effects of Aluminum Incorporation on the Young’s Modulus of 3C-SiC Epilayers
Authors: Messaoud Jaweb Ben , Michaud Jean François , Zielinski Marcin , Alquier Daniel
Published: July 2019

The silicon carbide cubic polytype (3C-SiC) is a material of choice to fabricate microelectromechanical systems. However, the mechanical properties of 3C-SiC-based devices are severely linked to the stress of the involved 3C-SiC material. Moreover, the stress level can hamper completing microsystems. As a consequence, in this study, we considered the influence of aluminum (Al) doping towards the mechanical properties of 3C-SiC epilayers and demonstrated a noticeable reduction of the Young’s modulus with a high Al incorporation.
Relationship between Temperature Dependencies of Resistivity and Hall Coefficient in Heavily Al-Doped 4H-SiC Epilayers
Authors: Matsuura Hideharu , Nishihata Rinya , Takeshita Akinobu , Imamura Tatsuya , Takano Kota , Okuda Kazuya , Hidaka Atsuki , Ji Shi Yang , Eto Kazuma , Kojima Kazutoshi , Kato Tomohisa , Yoshida Sadafumi , Okumura Hajime
Published: July 2019

The temperature dependencies of the resistivity and Hall coefficient for heavily Al-doped 4H-SiC epilayers with Al concentration (CAl) higher than 2×1019 cm-3 were investigated. The signs of measured Hall coefficients (RH) change from positive to negative at low temperatures. For the epilayers with CAl < 3×1019 cm-3 the sign inversion occurred in the hopping conduction region, which was reported to be explicable using the model for amorphous semiconductors. For the epilayers with CAl > 3×1019 cm-3, on the other hand, the sign inversion occurred in the band conduction region, which is a striking feature, because the movement of free holes in the valence band should make RH positive. The sign-inversion temperature increased with increasing CAl, while the dominant-conduction-mechanism-change temperature was almost independent of CAl.
Ultra-Fast and High-Precision Crystal Orientation Measurements on 4H-SiС
Authors: Schüler Nadine , Weißbach Torsten , Bradaczek Hans Arthur , Berger Hans , Dornich Kay
Published: July 2019

For a fast and precise crystal orientation of 4H-SiC, the so-called Omega-scan is presented. With this method the orientation can be determined within only 5 s. This paper presents a detailed study of different influences on the precision and repeatability of this method on 4H-SiC.
Study of Nitrogen Doping Effect on Lattice Strain Variation in 4H-SiC Substrates by Synchrotron X-Ray Contour Mapping Method
Authors: Ailihumaer Tuerxun , Yang Yu , Guo Jian Qiu , Raghothamachar Balaji , Dudley Michael
Published: July 2019

Variations in nitrogen doping concentration across the PVT-grown 4H-SiC wafers can induce significant lattice strain, leading to degradation on the performance of SiC-based power devices. A qualitative study on the lattice strain variation in facet and off-facet regions was carried out for 4H-SiC substrates. The lattice strain maps for 4H-SiC wafers were derived from the 11-20, 1-100 (transmission geometry) and 0008 (reflection geometry) using synchrotron double crystal contour mapping method. Results show that the lattice strain within the basal plane is isotropic, while along [0001] direction, lattice strain is one order of magnitude lower, indicating elastic anisotropy of strain due to doping in 4H-SiC crystals. The distribution of lattice strain inside the facet region is more uniform than in the off-facet region. Measurement of nitrogen doping concentration by Hall effect measurements shows over 45% of difference in doping level between heavily doped facet region and off-facet region. Existence of significant lattice distortion in facet region of 4H-SiC substrates was further confirmed by X-ray rocking curve measurements.
Electrical Characterisation of Thick 3C-SiC Layers Grown on Off-Axis 4H-SiC Substrates
Authors: Li Fan , Jokubavicius Valdas , Jennings Michael R. , Yakimova Rositza , Pérez Tomás Amador , Russell Stephen , Sharma Yogesh , Roccaforte Fabrizio , Mawby Philip  Andrew , La Via Francesco
Published: July 2019

300 μm thick 3C-SiC epilayer was grown on off-axis 4H-SiC(0001) substrate with a high growth rate of 1 mm/hour. Dry oxidation, wet oxidation and N2O anneal were applied to fabricate lateral MOS capacitors on these 3C-SiC layers. MOS interface obtained by N2O anneal has the lowest interface trap density of 3~4x1011 eV-1cm-2. Although all MOS capacitors still have positive net charges at the MOS interface, the wet oxidised sample has the lowest effective charge density of ~9.17x1011 cm-2.
Channeled Implantations of p-Type Dopants into 4H-SiC at Different Temperatures
Authors: Linnarsson Margareta K. , Hallén Anders , Vines Lasse , Svensson Bengt Gunnar
Published: July 2019

Channeling of B and Al ions in 4H-SiC(0001), has been investigated by secondary ion mass spectrometry (SIMS). Ion implantations have been performed between room temperature (RT) and 600 °C at various fluences. Before implantation, the major crystal axes were determined and the sample was aligned using the blocking pattern of backscattered protons. As expected, the depth distribution of the implanted ions along a crystal direction penetrates much deeper compared to non-channeling directions. At elevated temperatures, the channeling depth for 100 keV Al-ions is decreased due to lattice vibrations. For 50 keV B-ions, the temperature effect is minor, indicating a smaller interaction between target atoms and B. Simulations has been performed using SIIMPL, a Monte Carlo simulation code based on the binary collision approximation, to predict experimental data and get a deeper insight in the channeling process.
Increasing Laser-Doping Depth of Al in 4H-SiC by Using Expanded-Pulse Excimer Laser
Authors: Ikeda Akihiro , Shimokawa Takahi , Ikenoue Hiroshi , Asano Tanemasa
Published: July 2019

Al doping into 4H-SiC performed by irradiating pulse-width-expanded excimer laser to an Al film deposited on the 4H-SiC surface is investigated. An optical pulse stretcher was constructed to produce the laser pulse whose peak intensity was reduced as half as that of the original pulse and pulse width was expanded from 55 ns to 100 ns. The irradiation of the expanded pulses is found to reduce the ablation of the materials from the surface and enable irradiation of multiple shots. As the result, doping depth of Al is significantly increased. The multiple shots of the expanded pulses is also fund to decrease the sensitivity to spatial non-uniformity of laser intensity and increase the uniformity of doped region.
Optimization of the SiC Powder Source Size Distribution for the Sublimation Growth of Long Crystals Boules
Authors: Steiner Johannes , Arzig Matthias , Hsiao Ta Ching , Wellmann Peter J.
Published: July 2019

The influence of four different SiC source powder size distributions on the sublimation behavior during physical vapor transport growth of SiC was studied. The growth processes were carried out in a 3 inch crystal growth setup and observed in situ using advanced 3D computed tomography X-ray visualization. The single modal D90 size distribution of two source powders was 50 μm and 200 μm, respectively, with a corresponding average powder density of 1.17 g/cm3. The third source powder consisted of a blend of the previously named powders and exhibited an average powder density of 1.66 g/cm3 with a bimodal particle size distribution. The last source was composed of a solid polycrystalline SiC cylinder. The bimodal powder source exhibited a smoother morphology change and material consumption during the growth run and led to a much more stable shape change of the growth interface compared to the single modal source powders. The solid source featured the least morphology change. Therefore, with a careful adaption of the source material stable growth conditions can be achieved.
Raman Spectroscopy Characterization of Ion Implanted 4H-SiC
Authors: Xu Zong Wei , Song Y. , Rommel Mathias , Liu T. , Kocher Matthias , He Z.D. , Wang H. , Yao B.T. , Liu L. , Fang Feng Zhou
Published: July 2019

Raman spectroscopy and sheet resistance measurements were used to study the preparation processes of low-resistance p-type 4H-SiC by Al ion implantation with ion doses of 2.45×1012 - 9.0×1014 cm-2 and annealing treatment with temperatures of 1700 - 1900 °C. Greatly different from the LOPC (longitudinal optical phonon-plasmon coupled) Raman mode found from the sample of doping 4H-SiC during epitaxial growth, no significant influence on the surface concentration could be found for the longitudinal optical (LO) mode of Al-implanted 4H-SiC samples. When the Al surface concentration is larger than around 1018 cm-3, it was found that the intensity of the LO+ Raman peak (~ 980 - 1000 cm-1) increases and its full width at half maximum (FWHM) drops with the increase of surface concentration after annealing treatment. Moreover, for surface concentrations above 1018 cm-3, the LO+ Raman peak showed a left shift towards the LO peak, which could be related to the increase of free carrier concentration in the Al-implanted 4H-SiC samples. After higher annealing temperatures of 1800 °C and 1900 °C, the crystallinity of Al-implanted 4H-SiC was found to be improved compared to annealing at 1700 °C for surface concentrations larger than 1018 cm-3, which is consistent with the results of sheet resistance measurements.
Surface Characterization of Ion Implanted 4H-SiC Epitaxial Layers with Ion Energy and Concentration Variations
Authors: Kim Hong Ki , Kim Seongjun , Buettner Jonas , Lim Min Who , Erlbacher Tobias , Bauer Anton J. , Koo Sang Mo , Lee Nam Suk , Shin Hoon Kyu
Published: July 2019

In this study, Al and N implantation effect on surface properties of 4H-SiC epitaxial layers were investigated before annealing process. AFM results indicated that all implanted samples indicated relatively low RMS roughness values. From UPS and XPS analysis, work function and Si-C binding energy of implanted samples were increased compared to the reference 4H-SiC sample. Those variations may be caused by lattice disorder and amorphization. In addition, TEM image showed damaged area in 4H-SiC epitaxial layer.
Evidence of Channel Mobility Anisotropy on 4H-SiC MOSFETs with Low Interface Trap Density
Authors: Cabello Maria , Soler Victor , Haasmann Daniel , Montserrat Josep , Rebollo Jose , Godignon Philippe
Published: July 2019

In this work, we have evaluated 4° off-axis Si face 4H-SiC MOSFETs channel performance along both the [11-20] (perpendicular to steps) and [1-100] (parallel to steps) orientations, to evidence possible anisotropy on Si-face due to roughness scattering effect. Improved gate oxide treatments, allowing low interface state densities and therefore high mobility values, have been used on both NO and N2O annealed gate oxides. With these high channel mobility samples, a small anisotropy effect (up to 10%) can be observed at high electric fields. The anisotropy can be seen both at room and high temperatures. However, the optical phonon scattering is the dominant effect under these biasing conditions.
Microstructural Analysis of Ti/Ni Bilayer Ohmic Contacts on 4H-SiC Layers
Authors: Sundaramoorthy Vinoth , Kranz Lukas , Alfieri Giovanni
Published: July 2019

The micro-structural analysis of Ti/Ni bilayer as Ohmic contacts to n-type 4H-SiC is reported. There was no carbon segregation at the interface between the NiSi layer and the 4H-SiC layer for Ti/Ni contacts, unlike pure Ni contacts. The diffraction pattern image shows the presence of the cubic NiSi film which grows on the SiC surface. The film interface with the SiC was uniform and more planar. An optimized contact in terms of contact morphology was achieved using a bilayer contact Ti/Ni (20/100nm) annealed at 1100 °C for 5 minutes in vacuum.
Optimization of Ni/Nb Ratio for High-Temperature-Reliable Ni/Nb Silicide Ohmic Contact on 4H-SiC
Authors: Van Cuong Vuong , Ishikawa Seiji , Sezaki Hiroshi , Maeda Tomonori , Yasuno Satoshi , Koganezawa Tomoyuki , Kuroki Shin Ichiro
Published: July 2019

Low specific contact resistivity and high-temperature reliability of the Ni (x)/Nb (100-x) (where x = 25, 50, 75 nm) ohmic contact to 4H-SiC were investigated. After the annealing process at 1000°C for 3 min in N2 ambient, the I-V curves indicated that all the contacts exhibited the ohmic behaviors. Based on the transfer length method, the specific contact resistivity of the contacts were extracted. High concentration of Ni was responsible for low specific contact resistance of the Ni (75)/Nb (25)/4H-SiC sample by the formation of Ni2Si compound after the fabrication process. However, this contact lost the ohmic behavior at low temperature of 150°C. Whereas, both Ni (50)/Nb (50)/4H-SiC and Ni (25)/Nb (75)/4H-SiC contacts remained the ohmic behavior for 100-hour aging at 400°C. Two-dimensional X-ray diffraction analyses showed that the presence of carbon agglomeration formed at the interface of the Ni (75)/Nb (25)/4H-SiC contact caused the degradation of this sample when being aged at high temperature environment. Meanwhile, higher concentration of Nb in the Ni (50)/Nb (50)/4H-SiC and Ni (25)/Nb (75)/4H-SiC samples improved the ability to collect the excess carbon atoms and thus enhanced the high temperature reliability of these contacts when operating in high temperature ambient. Considering both low specific contact resistivity and high temperature reliability, the Ni (50)/Nb (50)/4H-SiC contact can be a good candidate for harsh environment applications.
Advances in In Situ SiC Growth Analysis Using Cone Beam Computed Tomography
Authors: Salamon Michael , Arzig Matthias , Uhlmann Norman , Wellmann Peter J.
Published: July 2019

Computed Tomography is becoming a valuable method for the in-situ monitoring of vapor grown silicon carbide single crystals [1]. Already the two-dimensional X-ray radiography has shown the potential of surveilling the growth process [2] and its characteristic features like the evolution of the facet, the crystal volume or the source material structure from one imaging plane. Even though the demands on imaging capability of the applied X-ray components used for a tomographic analysis are higher than for two-dimensional imaging, the extension of this method to the third dimension is highly beneficial. It allows investigating the full geometry and three-dimensional location of the features and by this provides a more accurate analysis. In this contribution we present the physical characteristics and the latest advances of our technique for the visualization of facets.
Laser Annealing Simulations of Metallisations Deposited on 4H-SiC
Authors: Berger Clément , Michaud Jean François , Chouteau David , Alquier Daniel
Published: July 2019

Based on finite elements method, thermal simulations were conducted to reproduce a laser annealing of several common metals deposited on 4H-SiC. We estimated the temperature reached at the metal/4H-SiC interface to check the possibility to achieve ohmic contact formation through laser annealing. An optimization of Al/Ti/4H-SiC stacking was also considered. Simulations highlighted the low temperature of the non-irradiated SiC face that allows using grinded wafer.
Temperature Dependency of Silicon Carbide MOSFET On-Resistance Characterization and Modeling
Authors: Dang Dinh Lam , Urbain Matthieu , Rael Stephane
Published: July 2019

Silicon carbide (SiC) MOSFET features low on-resistance per area even at high temperatures compared to a silicon (Si) counterpart with the same voltage rating. However, SiC MOSFET exhibits a unique behavior over operating temperatures due to the presence of interface trap charges. The effect of temperature on the on-resistance of SiC MOSFET has been studied through experimental measurements at difference temperatures from - 30 °C to 150 °C. The results show that high contribution of channel resistance is the critical factor to determine the behavior of SiC MOSFET with temperature.
1.2 kV SiC Trench-Gate MOSFETs with Dual Shielding Regions
Authors: Agarwal Aditi , Han Ki Jeong , Baliga B. Jayant
Published: July 2019

This paper presents a study of the 1.2kV UMOSFETs with dual shielding regions. Numerical simulations demonstrate the importance of including dual shielding regions to achieve low specific on-resistance and high breakdown voltage. The optimized structure has a low specific on-resistance (Ron,sp) of 2.19 mΩ-cm2, high breakdown voltage of 1470 V, low specific reverse transfer capacitance (Cgd,sp) of 17 pF/cm2 and excellent high-frequency figure-of-merit (HF-FOM) of 37 fs.
1.2-kV SiC Trench-Etched Double-Diffused MOS (TED-MOS)
Authors: Suto Takeru , Watanabe Naoki , Bu Yuan , Miki Hiroshi , Tega Naoki , Mori Yuki , Hisamoto Digh , Shima Akio
Published: July 2019

A novel structure, trench-eched double-diffused MOS (TED-MOS), were proposed. In this study, we demonstrate compatibility of reliability and small loss for applications to electric vehicle. To suppress the dielectric breakdown of gate insulator, a field relaxation layer (FRL) are formed above JFET region. Device simulation shows an effective decrease of electric field on gate dioxide, and furthure improvement of switching-and conduction-loss were expected. The fabricated TED-MOS chip doesn’t show gate leakage current even over 1600 V. We confirmed stable normally-off characteristic of the chip at 175 °C, and its Ron was 66 mΩ under Vg = 20 V and 175 °C condition. As an uniqueness to FRL TED-MOS, capacitance shows a steep decline with several step, which may attributed to depletion between FRL and p-Body and should contributed to the reduction of switching loss.
15 kV n-GTOs in 4H-SiC
Authors: Ryu Sei Hyung , Lichtenwalner Daniel J. , O’Loughlin Michael , Capell Craig , Richmond Jim , van Brunt Edward , Jonas Charlotte , Lemma Yemane , Burk Albert A. , Hull Brett , McCain Matthew , Sabri Shadi , O'Brien Heather , Ogunniyi Aderinto , Lelis Aivars J. , Casady Jeff , Grider David , Allen Scott , Palmour John W.
Published: July 2019

High performance 15 kV n-GTOs were demonstrated for the first time in 4H-SiC. The device utilized a 140 μm thick, lightly doped n-type drift layer, with 1450°C lifetime enhancement oxidation, which resulted in a carrier lifetime of 17.5 μs. The p+ backside injector layer was thinned to minimize parasitic resistances. A room temperature forward voltage drop of 5.18 V was observed at a current density of 100A/cm2. A 1 cm2 device showed a leakage current of 0.17 μA at 15 kV. The 4H-SiC n-GTO showed latching characteristics, and showed a turn-off time of 170 ns in a resistive load switching setup, which represents about a factor of 45 improvement in turn-off speed over 4H-SiC p-GTOs with comparable voltage and current ratings.
Silicon Carbide BJT Oscillator Design Using S-Parameters
Authors: Hussain Muhammad Waqar , Elahipanah Hossein , Rodriguez Saul , Malm B. Gunnar , Rusu Ana
Published: July 2019

Radio frequency (RF) oscillator design typically requires large-signal, high-frequency simulation models for the transistors. The development of such models is generally difficult and time consuming due to a large number of measurements needed for parameter extraction. The situation is further aggravated as the parameter extraction process has to be repeated at multiple temperature points in order to design a wide-temperature range oscillator. To circumvent this modelling effort, an alternative small-signal, S-parameter based design method can be employed directly without going into complex parameter extraction and model fitting process. This method is demonstrated through design and prototyping a 58 MHz, high-temperature (HT) oscillator, based on an in-house 4H-SiC BJT. The BJT at elevated temperature (up to 300 0C) was accessed by on-wafer probing and connected by RF-cables to the rest of circuit passives, which were kept at room temperature (RT).
Compact Modeling of SiC and GaN Junction FETs at High Temperature
Authors: Makris Nikolaos , Zekentes Konstantinos , Bucher Matthias
Published: July 2019

High temperatures and other harsh environments are domains of predilection for Junction FETs, particularly when wide band-gap semiconductors such as SiC or GaN are used. The present work describes the new compact model of double gate (DG) JFETs which is compared to TCAD simulations of SiC and GaN JFETs over a wide temperature range up to 500oC. The compact model is shown to be predictive of device behavior, for static (current-voltage) as well as dynamic (capacitance-voltage) behavior of long-channel DG JFETs.
Performance Limits of Vertical 4H-SiC and 2H-GaN Superjunction Devices
Authors: Zhou Xiang , Guo Zhi Bo , Chow T. Paul
Published: July 2019

We have evaluated the specific on-resistance (Ron,sp) vs. BV trade-off limit of vertical superjunction (SJ) devices for 4H-SiC and 2H-GaN using a previously published analytical model. In addition, we have identified and replaced some unsuitable assumptions found in previous work. Our results show that the Ron,sp of vertical SJ devices is between one and four orders of magnitude lower than the 1D limit of 4H-SiC and 2H-GaN devices at same breakdown voltage, but significantly higher than the previous projected limit for 4H-SiC. The optimized specific on-resistance for SJ devices is lower than that for conventional devices by factors of 3X and 100X for 1kV and 10kV devices respectively. These figures are, however, 25X higher than previous projections.
Development of SOI FETs Based on Core-Shell Si/SiC Nanowires for Sensing in Liquid Environments
Authors: Bange Romain , Bano Edwige , Rapenne Laetitia , Mantoux Arnaud , Saddow Stephen E. , Stambouli Valerie
Published: July 2019

Core–shell Si/SiC nanostructures appear as promising building blocks for sensing applications, thanks to the high chemical stability of SiC coupled with the semiconducting properties of Si. In order to optimize the fabrication process of such structures, Si nanowires were coated with a thin SiC layer, and integrated as back-gated field-effet transistors. Two approaches for the fabrication of the SiC shell were then investigated. The first approach involves chemical vapor deposition of amorphous SiC on Si nanowires, without the need for masking; the second approach involves carbonization of Si surfaces to produce a thin crystalline SiC layer, but requires a larger thermal budget. The resulting structures were analyzed using high-resolution transmission electron microscopy (HR-TEM), and the devices were characterized electrically. Electrical characterization shows that the carbonization approach induces a dramatic decrease in drain-to-source current associated with gate leakage, whereas the electrical performances were preserved in the case of chemical deposition.
First-Principles Study on Photoluminescence Quenching of Divacancy in 4H SiC
Authors: Csо́rе́ András , Magnusson Björn , Son Nguyen Tien , Gällström Andreas , Ohshima Takeshi , Ivanov Ivan , Gali Ádám
Published: July 2019

In this work, quenching effect in the photoluminescence (PL) spectrum of divacancy defects in 4H SiC is investigated. Quenching in PL occurs when photoexcitation with an energy below a certain threshold is applied. In order to understand this phenomenon, we carried out Kohn-Sham density functional theory (DFT) calculations. In accordance with recent experimental results, we propose a physical model which explains the quenching phenomenon.