bluuebunny/crossref_metadata_2025 huggingface dataset:
Teknologi dan Produksi Akuakultur di Danau Tondano Kabupaten Minahasa
Authors: Mambrasar Deni , Salindeho Indra R.N , Tumembouw Sipriana
Published: July 2019

The aim of this study was to know the  applied technology and the production value of the aquaculture activities in the waters of  Lake Tondano and to identify factors influencing aquaculture production in Tondano lake. Data collected  consisted of primary and  sekunder data.  Primary data  were collected by conducting a survey to fish-farmers as respondents around the lake Tondano.  Operational aquaculture data were obtained  by interviewing the fish farmers and by observation.  Secondary data were collected from various  institution  such as Minahasa  Fisheries  Office  ,  Office of  Village Head and Fish-farmer  Group  Administrative Centre.  Collected data were  descriptively analyzed  and presented in the form of tabulation and various model of diagram.  Fluctuated data in aquacultural production value  and the number of  operated  KJT  during the periood of  2001 to  2014 was analysed by using linear regression  and correlation. The aquacultral production value  of the lake Tondano in  2014 was  estimated only 1227,3 tons /year.  The number of operated  KJT  only remained 1203 units.  The production value decreased consistently  from 2003 to 2014.   Statistical analysis showed that during  2001-2014 there was a reduction about 1.236 ton every year in aquacultural production, and  607 units of operated KJT.  There was a  very strong correlation  between  time  (year) and the  the aquacultural production, and also between  time (year) and  the number  of  operated KJT.  There were 3 important  factors  influencing the aquacultural production value of lake Tondano, which were: environmental, technical and economic factor.   However, the primary factor  was  ‘economic’ factor.  The  ‘very high price’ of the fish formulated diet  and  the "very low price”  of  the produced fish were the main causes of the problem.   The fish farmers could not afford the invesment and operational cost.   Environmental degradation of  Lake Tondano waters  also significantly  influenced the operation of aquacultural activities.   Keywords:  Production, technology, aquaculture, Lake Tondano
Budidaya Ikan Kerapu (Epinephelus tauvina Forsskal, 1775) dan Ikan Beronang (Siganus canaliculatus Park, 1797) dalam Karamba Jaring Apung dengan Sistim Polikultur
Authors: Paruntu Carolus Paulus
Published: July 2019

The aim of the present research was to evaluate the daily growth ratio, food conversion ratio and mortality of grouper (Epinephelus tauvina) and rabbit fish (Siganus canaliculatus) in floating net with polyculture system.  This experiment was done at the coastal area of Tomini Bay in the North Sulawesi Province.  The observations were done every two weeks for three months from August - November 2014.  Twenty five groupers (62.41 grams in ABWo) and twenty five rabbit fish (52.2 grams in ABWo) were used for polyculture experiment, while fifty groupers (56.71 grams in ABWo) for monoculture.  The results indicated that the daily individual growth of Epinephelus tauvina on polyculture was 1.29%, with food conversion ratio 6.1, while it on monoculture was 1,18%, with food conversion ratio 6.4.  The daily individual growth of Siganus canaliculatus on polyculture was 0,8%, with food conversion ratio 3.8.  Mortality for all species studied were 0%.  The present research showed that the polyculture system was better than monoculture system.  The future studies suggest that the polyculture system in the floating net may be developed and applied as a mariculture model in the North Sulawesi Province for prosperous life of fisherman. Keywords: Epinephelus tauvina,  Siganus canaliculatus, polyculture system, floating net, prosperous life,  fisherman.
KEMIRINGAN LERENG DAN GRANULOMETRI SEDIMEN GISIK TANJUNG MERAH, BITUNG SULAWESI UTARA
Authors: Sapsuha Isman , Rampengan Roy M , Opa Esry T , Manengkey Hermanto WK , Pelle Wilmy E , Tilaar Ferdinand F
Published: July 2019

ABSTRACTBeach slope and sediment granulometry  is one of the importat aspect in coastal management.  Beach offers a variety of functions and potential to be utilized. In the interests of phisical use in the beach, coastal structure in the form of groynes has been built. Actually, the groin has been used as a dock. This research was conducted with the aim of revealing the slope and granulometry sediment in Tanjung Merah beach. The results obtained, the beach slope is considered sloping and very sloping, the composition of the sediment consists mainly  of medium sand, fine sand and very fine sand. Sediment distribution analysis obtained results, the main grain size was mainly in the form of medium sand, sorting was mainly classified as poor, skewness was mostly asymmetrie strong to large size, most curtosis was mesokurtic. The results of the study indicate the occurrence of the process of erosion and deposition ia certain spaces on the beach studied.

Keywords: Tanjung Merah, beach slope, sediment granulometry

Kemiringan lereng dan granulometri sedimen gisik merupakan salah satu aspek penting dalam pengelolaan pantai. Gisik menawarkan beragam fungsi dan potensi untuk dimanfaatkan. Dalam kepentingan pemanfaatan lahan gisik, berbagai modifikasi dilakukan oleh manusia. Pada gisik di Tanjung Merah, telah dibangun struktur pantai berupa groin. Secara aktual, groin tersebut telah difunsikan sebagai dermaga. Penelitian ini dilakukan dengan tujuan mengungkapkan kemiringan dan granulometri sedimen di gisik Tanjung Merah. Hasil penelitian yang diperoleh, lereng gisik terkriteria miring dan sangat miring, komposisi sedimen terutama terdiri dari pasir sedang, pasir halus, dan pasir sangat halus. Analisis distribusi memperoleh hasil, rataan empirik terutama berupa pasir sedang, penyortiran terutama terklasifikasi buruk, kemencengan terbanyak berupa asimetris kuat ke ukuran besar, peruncingan terbanyak berupa mesokurtik. Hasil studi mengindikasikan terjadi proses erosi dan deposisi pada ruang-ruang tertentu di gisik yang ditelaah.Kata kunci : Tanjung Merah, kemiringan lereng, granulometri sedimen
Factores asociados a la estancia hospitalaria prolongada en adultos mayores
Authors: Jesus-Carbajal Celenne L. , Ventura-Jorge Líz M. , Mena-Parco Juan
Published: July 2019

Introducción: Los adultos mayores tendrán mayor incremento proporcional a nivel mundial y con esto pérdida prematura de su capacidad funcional lo que determina los días de hospitalización. Objetivo: determinar la asociación de las caídas, las comorbilidades y la malnutrición como factores de riesgo de la estancia hospitalaria prolongada en adultos mayores. Métodos: se realizó un estudio de casos y controles en adultos mayores de 60 años y más hospitalizados en el período del 1 de agosto hasta 31 de octubre del 2018. La muestra de 84 pacientes fue dividida en dos grupos, menos de 6 días de hospitalización (control) y los de 6 y más días (casos). Se utilizó prueba de chi cuadrado y un análisis inferencial bivariado. Resultados: del total el grupo de 75 años y más representó 27,38 % (casos) y el grupo de 60 a 74 años fue 30,95% (controles). Observamos asociación estadística significativa con las comorbilidades y la malnutrición con odds ration (OR) de 1 y 1,27 (p < 0,05) respectivamente. Y así mismo con las variables intervinientes género y estado civil con OR de RP de 2,17 y 1 (p < 0,05). Pero no se pudo hallar asociación estadística significativa de la variable caídas con estancia hospitalaria prolongada con OR de 0,59 (p > 0,05). Conclusión: No existe asociación de la variable caídas, comorbilidades y malnutrición. Si existe asociación del género (masculino) y estado civil (casado y viudo) como factores de riesgo de la estancia hospitalaria prolongada del Hospital EsSalud II Huánuco en el 2018.
Metasomatic Processes in the Lithospheric Mantle Beneath the No. 30 Kimberlite (Wafangdian Region, North China Craton)
Authors: Zhu Ren Z. , Ni Pei , Ding Jun Y. , Wang Guo G. , Fan Ming S. , Li Su N.
Published: July 2019

This paper presents the first major and trace element compositions of mantle-derived garnet xenocrysts from the diamondiferous No. 30 kimberlite pipe in the Wafangdian region, and these are used to constrain the nature and evolution of mantle metasomatism beneath the North China Craton (NCC). The major element data were acquired using an electron probe micro-analyzer and the trace element data were obtained using laser ablation inductively coupled plasma-mass spectrometry. Based on Ni-in-garnet thermometry, equilibrium temperatures of 1107–1365 °C were estimated for peridotitic garnets xenocrysts from the No. 30 kimberlite, with an average temperature of 1258 °C, and pressures calculated to be between 5.0 and 7.4 GPa. In a CaO versus Cr2O3 diagram, 52% of the garnets fall in the lherzolite field and 28% in the harzburgite field; a few of the garnets are eclogitic. Based on rare earth element patterns, the lherzolitic garnets are further divided into three groups. The compositional variations in garnet xenocrysts reflect two stages of metasomatism: early carbonatite melt/fluid metasomatism and late kimberlite metasomatism. The carbonatite melt/fluids are effective at introducing Sr and the light rare earth elements, but ineffective at transporting much Zr, Ti, Y, or heavy rare earth elements. The kimberlite metasomatic agent is highly effective at element transport, introducing, e.g., Ti, Zr, Y, and the rare earth elements. Combined with compositional data for garnet inclusions in diamonds and megacrysts from the Mengyin and Wafangdian kimberlites, we suggest that these signatures reflect a two-stage evolution of the sub-continental lithospheric mantle (SCLM) beneath the NCC: (1) early-stage carbonatite melt/fluid metasomatism resulting in metasomatic modification of the SCLM and likely associated with diamond crystallization; (2) late-stage kimberlite metasomatism related to the eruption of the 465 Ma kimberlite.
Energy distribution in an ensemble of nanoparticles and its consequences
Authors: Vollath Dieter
Published: July 2019

In general, considerations about isothermal ensembles of nanoparticles assume that each one of the particles is at the same temperature. However, there are experimental indications that such an isothermal ensemble does not exist. Therefore, it is advised to analyze phenomena connected to the temperature distribution within such an ensemble. The detailed analysis presented in this work led to the assumption of a normal distribution of the energy within an ensemble of nanoparticles where basic properties of such an “isothermal” ensemble can be predicted. The width of the energy distribution decreases with increasing particle size. This particle size dependence of the energy per particle controls phase fluctuations in the vicinity of the transformation temperature. Additionally, applying the temperature profile of a phase transformation, it is possible to calculate the particle size distribution of the ensemble with a precision within the scattering range of the experimental data. This is the most important application of this analysis and coincidently a proof of the basic premise. The basic quantity determining the width of the energy distribution is the heat capacity of the particles. For these calculations, bulk data for the heat capacity were successfully applied. This leads to the conclusion that the data for heat capacity of nanoparticles are very close to the bulk values.
Nouvelles routes de la soie et endiguement économique et financier de la Chine par les États-Unis
Authors: Estachy Laurent
Published: July 2019

L’initiative chinoise des nouvelles routes de la soie ne constitue pas une réminiscence sentimentale des voyages de Marco Polo, comme le soulignait en 2018 le ministre des Affaires étrangères allemand Sigmar Gabriel. Selon lui, cette initiative « se positionne comme une tentative pour établir un système cohérent, destiné in fine à façonner le monde dans le sens des intérêts chinois ». De façon plus générale, la réflexion doit être resituée dans le cadre d’une « Grande Stratégie » chinoise, de nature « mercantiliste », visant à remplacer les États-Unis comme puissance hégémonique mondiale. Telle est en tout cas la vision de la nouvelle administration américaine depuis novembre 2016 et l’élection du Président Donald Trump. Ainsi, à une « Grande » Stratégie chinoise répondrait désormais une « contre » stratégie américaine. Au-delà des routes de la soie, il s’agit en effet pour les États-Unis de contenir la montée en puissance de la Chine sous toutes ses formes ; industrielles, technologiques, commerciales, financières, diplomatiques et militaires.
Accidents de sport en Haute-Savoie : données de l’Enquête EPAC 2004-2013
Authors: Jennings Paul , Massoutier Maximilien , Pedrono Gaëlle , Baysson Hélène , Ricard Cécile , Detrez Marc-Antoine , Thélot Bertrand , Courtois Xavier
Published: July 2019

La pratique d’une activité physique et sportive régulière est bénéfique pour la santé mais elle peut également occasionner un accident de sport dont la gravité peut être élevée. Les données enregistrées de 2004 à 2013 dans le cadre de l’Enquête permanente sur les accidents de la vie courante (EPAC), dans un service d’urgences d’un centre hospitalier de Haute-Savoie, ont été analysées afin de décrire les caractéristiques des accidents de sport dans une région particulièrement attractive pour les sports d’hiver et les sports aériens. Au total 43 505 accidents de sport ont été enregistrés : les sports d’équipe (30 %), les sports d’hiver (25 %) et le cyclisme (23 %) étaient les sports les plus représentés. Ces accidents concernaient davantage les hommes que les femmes (sex-ratio = 2,3), et la tranche d’âge 10-14 ans (21 % des accidentés). Tous sports confondus, les chutes ont été le mécanisme accidentel le plus fréquent. L’escalade, les sports d’hiver et les sports aériens sont les sports ayant entraîné le plus d’hospitalisations. Le risque d’hospitalisation suite à un accident de sport était plus élevé chez les hommes, quand l’âge augmentait et quand le lieu de résidence était situé hors de la Haute-Savoie. Des travaux complémentaires sont recommandés pour mesurer l’impact sur la survenue d’accident de l’utilisation de moyens de protection (casque, gants), du niveau de pratique et d’encadrement, ou de l’appartenance à un club sportif sur le risque d’hospitalisation.
Rural Orthopedics: Providing Orthopedic Care in Rural Communities
Authors: Lese Andréa , Sraj Shafic
Published: July 2019

Providing orthopedic care to rural communities is challenging. Delivering adequate orthopedic care is challenged by delay in presentation, underestimation of urgency, need for subspecialty services, and deficiencies in local support services. Collaboration efforts, peer-to-peer consultations, outreach clinics, virtual consults, electronic consults, and telemedicine are useful strategies. Individual treatment strategy must accommodate the burden on the patient, and patient education is important. Treatment options that require frequent travel should be avoided. Orthopedic surgery is in high demand in rural communities but unfortunately is limited in availability. Strategies are available for improving access to orthopedic care in rural areas. [
Orthopedics
. 2019; 42(4):e350–e355.]
Neurofibromatosis Type 1: A Population-Based Study
Authors: Bata Bashar M. , Hodge David O. , Mohney Brian G.
Published: July 2019

Purpose:

To report the incidence, demographics, and clinical manifestations of neurofibromatosis type 1 among a population-based cohort of patients.

Methods:

The medical records of all patients diagnosed as having neurofibromatosis type 1 while residing in Olmsted County, Minnesota, from January 1, 1980, through December 31, 2009, were retrospectively reviewed.

Results:

Fifty patients were diagnosed as having neurofibromatosis type 1 during the 30-year period, yielding an incidence of 1.2 per 100,000 individuals. The mean age at diagnosis was 11.7 years (95% confidence interval [CI]: 0.2 to 47) and 26 (52%) were males. Twenty-eight patients were new mutations, yielding a de novo mutation rate of 56%. During a mean follow-up of 9.8 years (range: 3 weeks to 32 years), café-au-lait macules were diagnosed in 49 individuals (98%), neurofibromas in 26 (52%), and skeletal anomalies in 14 (28%). Three (5.9%) individuals were diagnosed as having glioma of the central nervous system (95% CI: 1.2 to 9.7%) at a mean age of 13 years (range: 5 to 26 years), including 1 patient with optic nerve glioma diagnosed at the age of 26 years. Only 1 (2%) patient was diagnosed as having malignant nerve sheath tumor.

Conclusions:

Although the prevalence and de novo mutation rate of neurofibromatosis type 1 in this population-based study were similar to prior reports, the occurrence of optic nerve gliomas was much lower.

[
J Pediatr Ophthalmol Strabismus
. 2019;56(4):243–247.]
Evaluation of a Free Public Smartphone Application to Detect Leukocoria in High-Risk Children Aged 1 to 6 Years
Authors: Vagge Aldo , Wangtiraumnuay Nutsuchar , Pellegrini Marco , Scotto Riccardo , Iester Michele , Traverso Carlo Enrico
Published: July 2019

Purpose:

To determine whether a white-eye detector smartphone application (app) can be used as a screening tool to detect early signs of leukocoria in a clinical practice.

Methods:

A prospective, single-visit study of children aged 1 to 6 years presenting for a complete pediatric ophthalmologic examination was conducted. All children who met the enrollment criteria were screened by an orthoptist with the CRADLE (Computer Assisted Detector of Leukocoria) smartphone app for an iPhone operating system (iOS) (iPhone 7; Apple, Cupertino, CA). Cycloplegic retinoscopy and fundus examination were performed 30 minutes after one to two drops of a pediatric combination drop, comprising tropicamide 1% and phenylephrine 2.5%, were instilled. A comparison between the two methods yielded sensitivity, specificity, and negative likelihood ratio values.

Results:

A total of 244 eyes of 122 children were included in the study. Nine eyes of 244 (3.6%) had leukocoria evaluable by penlight caused by amblyogenic cataract, 1 (0.4%) patient had retinopathy of prematurity stage 5, and 3 (1.2%) patients had retinoblastoma. The sensitivity of the white-eye detector app was 15.38% (95% confidence interval [CI]: 1.92% to 45.45%), the specificity was 100% (95% CI: 98.48% to 100.00%), and the negative likelihood ratio was 0.85 (95% CI: 0.67 to 1.07).

Conclusions:

A smartphone photoscreening app able to detect leukocoria may provide valuable support for children's parents. However, it cannot be considered an alternative to the ophthalmoscope for children.

[
J Pediatr Ophthalmol Strabismus
. 2019;56(4):229–232.]
A Small and Portable Foot Motion Recognition Device Used in VR Environment
Authors: Wu Huayue , Zhao Xiangmo
Published: July 2019

Foot motion recognition plays an important role in VR interaction. The VR treadmill is the mainstream device used for foot motion recognition. However, they have many restricts and usually bring users unnatural experiment. In this article, a small and portable device is designed with a gyroscope to collect the user's foot attitude data and transmit data through Bluetooth to a computer for further analysis. A new adaptive foot motion algorithm is also proposed for the recognition device. The algorithm decomposes the foot motion attitude data into three components, analyses the motion status in the three components, and composes the motion status to generate the final motion direction and speed. A performance evaluation shows that the proposed algorithm could rapidly and accurately recognize the foot motion and the device that was designed could bring a user a much more natural experience in a VR environment.
Clustering of Web Application and Testing of Asynchronous Communication
Authors: Pradhan Sonali , Ray Mitrabinda , Patnaik Srikanta
Published: July 2019

In model-based testing, testing is done using Input Output Transition System (IOTS) or Finite State Machine (FSM). In synchronous testing, it is easy to know the proper sequence of input output of the system under testing, whereas, in asynchronous communication, it is tough to trace the sequences of inputs and outputs. A web application is an example of asynchronous processing, in which input/output queue management is a common issue for testing in asynchronous JavaScript and XML user interfaces. This article discusses asynchronous testing of web application by taking a Gmail account as a case study. In this article, the web application is partitioned into clusters by determining logical web pages that implement logical functions. The clusters of page objects are represented using finite state machines. From the FSMs, test scenarios are generated. The size of the test cases covering longer paths is decreased by making clusters of states. The authors conduct a queue analysis using a test architecture to investigate the behavior of the system under testing. Finally, the test cases are generated using the Selenium tool.
The Economics of Disaster Risk Management in Nepal
Authors: Prasad Uma Shankar
Published: July 2019

Nepal is highly vulnerable to many disasters and substantially increasing every year. It has been creating an adverse impact on human lives, livelihoods, and infrastructures. The primary objective of this study is to state the human causalities and economic loss from disasters in Nepal and suggest institutional and system reforms for effective disaster risk management in the country. This is an analytical study based on secondary data. Data published from various government and non-government organizations are used to analyse the situation. Although the findings of the study reveal that the Government of Nepal has been continuously carrying out many efforts for fighting against various levels of disasters in the country, it concludes that additional efforts are needed from the federal to the local level at all phases of disaster management including preparedness, response, and recovery. It is also important to integrate disaster risk reduction and climate change adaptation policies, plans and programmes into national development.
Identifying Accident Factors in Military Aviation
Authors: Nitzschner Marco Michael , Nagler Ursa K J , Stein Michael
Published: July 2019

Investigating accidents is an important method to enhance safety in aviation. Nevertheless, it is equally important to examine trends and factors across different accidents to adapt accordingly. Therefore, in the first study, 48 accidents and incidents occurring to manned military aircraft of the German Armed Forces between the years 2004 and 2014 were analyzed using the HFACS framework. Results show that preconditions for unsafe acts (37.7%) was observed most often, followed by unsafe acts (36.2%) and organizational influences (17.9%). Unsafe supervision was observed least often (8.2%). Thus, operators on the front line contribute the major part to manned aircraft incurrences in the German Armed Forces while higher levels of HFACS seem to play a smaller part. In the second study, 33 accidents and incidents occurring to unmanned military aircraft of the German Armed Forces between 2004 and 2014 were analyzed, also using the HFACS framework. Results show that technical issues were mentioned most often and human factors were identified considerably less than in manned aircraft.
Vapor Growth of 3C-SiC Using the Transition Layer of 3C-SiC on Si CVD Templates
Authors: Schuh Philipp , Künecke Ulrike , Litrico Grazia , Mauceri Marco , La Via Francesco , Monnoye Sylvain , Zielinski Marcin , Wellmann Peter J.
Published: July 2019

We present three different ways of transferring 3C-SiC layers grown on silicon on top of a SiC carrier using a carbon glue layer. Our main focus was upon the growth on the transition layer, as 3C-SiC does not feature any polarities in the <100> or <-100> direction. We realized a stable and reproducible process by following a wet chemical approach, dealing with the difficulties of handling thin but freestanding 3C-SiC layers. By using this way, we transferred approximately 130 μm thick pieces using their horizontal hot-wall reactor (M10), which were chemo mechanically polished and afterwards fixed on our SiC carriers. Implementing such a seeding stack into our growth setup, we managed to grow between 20 μm and 130 μm thick layers on top. We have proven the possibility to grow on the transition layer. Furthermore, we observed a slight reduction in protrusion density, which is currently one of the main defects in such layers.
Monitoring of Substrate and Epilayer Surfaces by Mirror Projection Electron Microscope
Authors: Kamata Isaho , Ohira Kentaro , Kobayashi Kenji , Hasegawa Masaki , Miyata Mitsuyasu , Noguchi Naoto , Takami Shinichiro , Tsuchida Hidekazu
Published: July 2019

4H-SiC surfaces before and after epitaxial growth (substrate and epitaxial layer surfaces) were investigated by mirror projection electron microscopy (MPJ) and atomic force microscopy (AFM). On the epitaxial layer surface, two types of short-step-bunchings (SSBs) were observed, one of which featured double grooves and protrusion perpendicular to the step-flow direction and the other, a single groove and protrusion. We also investigated the substrate surface and detected features of sub-surface damage and dislocations. These surfaces were compared and the relationship between the SSBs on the epitaxial layer surface and sub-surface damages and dislocations on the substrate surface were discussed.
Dynamics Analysis of Single Shockley Stacking Fault Expansion in 4H-SiC P-i-N Diode Based on Free Energy
Authors: Kano Akira , Goryu Akihiro , Kato Mitsuaki , Ota Chiharu , Okada Aoi , Nishio Johji , Hirohata Kenji
Published: July 2019

Expansion of single Shockley stacking faults (SSFs) during forward current operation is an important issue, because it decreases the reliability of 4H-SiC bipolar devices. In this paper, we propose a method for analyzing SSF dynamics based on free energy under current conduction, temperature, and resolved shear stress conditions. The driving force for dislocation dissociation reactions and formation of SSFs is incorporated into the free energy function, including chemical potential, stacking fault energy, crystallographic energy, gradient energy and elastic strain energy. The net energy gain of the chemical potential was calculated as a function of temperature and current conduction through use of the a TCAD device simulator based on the Boltzmann equation, Poisson equation and the current continuity equation concerning electron and hole distributions with self-consistency. It was confirmed that SSF dynamics can be simulated by the proposed method. It was also found that SSF formation can be attributed to quantum well variation in which electrons in n-type 4H–SiC enter SSF-induced quantum well states to lower the energy of the dislocation system.
Dislocations Propagation Study Trough High-Resolution 4H-SiC Substrate Mapping
Authors: Anzalone Ruggero , Piluso Nicolo , Severino Andrea , Lorenti Simona , Arena Giuseppe , Coffa Salvo
Published: July 2019

In this work a deep investigation of the dislocation on 4H-SiC substrate has been shown. The dislocation intersecting the surface were enhanced by KOH etching at 500 deg. C. performed on whole 6 inches substrate. A comparison between basal plane dislocations and threading screw dislocations in the substrate with the defects in the epitaxial layer (mainly stacking faults and carrots) was performed. The comparison between shows a correlation between basal plane dislocations density and stacking faults density maps.
Effect of Defects in Silicon Carbide Epitaxial Layers on Yield and Reliability
Authors: Das Hrishikesh , Sunkari Swapna , Justice Joshua , Pham Helen , Park Kyeong Seok
Published: July 2019

Inline metrology tools are widely used to detect defects in SiC epitaxial layers. The defect statistics are used in a variety of ways to determine quality, pass/fail and screen affected die. In this work, we document the automated detection and classification of various epitaxial defects based on type and origin. We further classify these categories into killer and non-killer defects and compare them to the electrical yield of Schottky Diodes. The origins of these defects are determined in broad categories, resulting in a clustering and yield-scaling model, which agrees very closely to experimental data. Further, we look at on-wafer screening techniques of potential weak die by both defect tagging and unclamped inductive switching (UIS) stress testing. Successful 1000-hr reliability tests show the robustness of our detection and screening methods.
Evaluation of Effect of Mechanical Stress on Stacking Fault Expansion in 4H-SiC P-i-N Diode
Authors: Goryu Akihiro , Kano Akira , Kato Mitsuaki , Ota Chiharu , Okada Aoi , Nishio Johji , Izumi Satoshi , Hirohata Kenji
Published: July 2019

Single Shockley stacking faults (SSFs) expand from basal plane dislocations (BPDs) under forward current operation of 4H-SiC bipolar devices, giving rise to a reliability deterioration mode called “bipolar degradation”. Several groups have proposed models for the expansion of SSFs, in which the SSFs expand when electron-hole pair recombination takes place at BPDs. Maeda proposed a formulation of SSF expansion that includes stacking fault energy. However, the mechanisms by which mechanical stress affects the expansion of SSFs are unclear. In this paper, we evaluated the “expansion threshold current” of bar-shaped SSFs in a mechanical stress field using a p-i-n diode fabricated on 4H-SiC. To confirm the effect of mechanical stress on the threshold current for bar-shaped SSF expansion, a SiC-p-i-n diode was evaluated by the four-point bending method. Experimental results show that the threshold current of SSFs decreases or increases by more than 100 A/cm2 depending on the direction of the applied stress of SSFs. This result indicates that mechanical stress is an important factor for SiC bipolar device design.
Deep Electronic Levels in n-Type and p-Type 3C-SiC
Authors: Schöler Michael , Lederer Maximilian W. , Wellmann Peter J.
Published: July 2019

In recent times, 3C-SiC is gaining more and more interest in terms of applications for optoelectronics and quantum computing. Cubic SiC exhibits a number of luminescent defects in the near infrared originating from deep electronic levels. Temperature dependent photoluminescence measurements were conducted on n-type and p-type 3C-SiC in order to investigate the formation of dopant related point defects as well as intrinsic point defects and defect complexes. The results indicate a number of VSi, VC and VCCSi related defects which might be suitable candidates for future optoelectronic applications.
High Resolution Investigation of Stacking Fault Density by HRXRD and STEM
Authors: Barbagiovanni Eric G. , Alberti Alessandra , Bongiorno Corrado , Smecca Emanuele , Zimbone Massimo , Anzalone Ruggero , Litrico Grazia , Mauceri Marco , La Magna Antonino , La Via Francesco
Published: July 2019

The effect of varying growth rate on the formation of defects in homo-epitaxially grown cubic silicon carbide (3C-SiC) is studied. Three growth rates are considered (30, 60 and 90 μm/hr) demonstrating that as the growth rate increases the density of point defects, as demonstrated by photo- luminescence, and stacking faults (SFs), as measured by a KOH etching procedure, increase. Scanning transmission electron microscopy images demonstrate generation, annihilation and closure of SFs as a function film thickness. High resolution X-ray diffraction is used to uncover the higher quality of homo-epitaxial with respect hetero-epitaxial films through the examination of the sample mosaicity and SF density.
Nano and Micro-Scale Simulations of Si/4H-SiC and Si/3C-SiC NN-Heterojunction Diodes
Authors: Rashid Muhammad Haroon , Koel Ants , Rang Toomas
Published: July 2019

In the last decades, silicon carbide (SiC) based heterostructures have gained a remarkable place in research field due to their exceptional properties. These properties make SiC highly suitable for high temperature, high frequency, and high power electronics applications. The most prominent polytypes (among 200 types) of SiC like 3C-SiC, 4H-SiC and 6H-SiC, have distinctive electrical and physical attributes that make them promising candidates for high performance optoelectronic applications. Silicon (Si) also has been accepted as a promising material for wide range of electronic, optical and optoelectronic applications. Heterostructures fabricated by the direct bonding of SiC polytype and Si may have interesting physical and electrical attributes. In this paper, micro and nano-scale simulations of the nn-heterostructures of Si/4H-SiC and Si/3C-SiC have been done with Silvaco TCAD and QuantumWise Atomistix Toolkit (ATK) softwares respectively. Voltage-current density characteristics of the nanoscale and microscale simulated devices are computed and discussed. In nanoscale devices, the effects of defects due to lattice misplacements (axial displacement of bonded wafers) are also studied. These simulations are the preparation for our future experiments, which are targeted to produce either a high electron mobility diode or a light emitting diode, by direct bonding (diffusion welding) of SiC polytypes.
Characterization of β-Silicon Carbide and Potential Use as Irradiation Temperature Monitor
Authors: Vande Pitte Jonas , Detavernier Christophe , Lauwaert Johan , Uytdenhouwen Inge , Gusarov Andrei , Wagemans Jan
Published: July 2019

Post-irradiation data on the neutron-induced swelling behaviour and resistivity changes in silicon carbide often does not show a clear trend. This makes a quantitative comparison between different studies difficult. To address the diverging results after irradiation in different studies, a thorough reference study is performed on high quality β-silicon carbide. The results show the response to neutron irradiation may be significantly influenced by structural defects present before irradiation. These findings open a way to improve the accuracy of silicon carbide irradiation temperature monitors.
Polytype Control by Pretreatment of SiC Source Powder for 4H-SiC Single Crystal Growth
Authors: Choi Jung Woo , Kim Jung Gyu , Jang Byung Kyu , Ko Sang Ki , Kyun Myung Ok , Seo Jung Doo , Ku Kap Ryeol , Lee Chae Young , Lee Won Jae
Published: July 2019

4H-SiC single crystal was successfully grown with source powder modified by the pretreatment process in order to improve polytype stability of SiC crystal. To increase C/Si ratio in SiC source powder, SiC source powder was mixed with liquid carbon source and then pre-heated at 1200°C. SiC single crystal grown with modified source powder exhibited complete 4H polytype and the crystal quality of SiC crystal grown by modified source power was definitely better than conventional source powder
Fabrication and Characterization of 3.3-kV SiC DMOSFET with Self-Aligned Channels Formed by Tilted Ion Implantation
Authors: Morikawa Takahiro , Sato Shintaroh , Shima Akio
Published: July 2019

SiC DMOSFET with self-aligned channels was fabricated and characterized. The process features self-aligned channel formation by utilizing tilted ion implantation. We confirmed that channel areas were successfully formed along both sides of the stripe cell. Electrical measurements revealed that the characteristics of the fabricated DMOSFET chips had sufficiently high blocking voltage and moderate values of threshold voltage and on-state resistance. These experimental results show the proposed process can be an easy option for fabrication of SiC DMOSFET.
Activation Energy for the Post Implantation Annealing of 1019 cm-3 and 1020 cm-3 Ion Implanted Al in 4H SiC
Authors: Nipoti Roberta , Canino Maria Concetta , Sapienza Sergio , Bellettato Michele , Sozzi Giovanna , Alfieri Giovanni
Published: July 2019

The activation energy for the electrical activation of 1x1019 cm-3 and of 1x1020 cm-3 ion implanted Al in 4H-SiC has been estimated. Ion implantation temperature and dose rate were in the range 430-500°C and around 1011 cm2s-1, respectively. Post implantation annealing temperatures varied between 1500 °C and 1950 °C. The annealing time per each annealing temperature was sufficiently long that the sheet resistance of the implanted layer could be equal to the stationary value at the applied annealing temperature. The Arrhenius plots of the room temperature sheet resistances with respect to the post implantation annealing temperatures featured an exponential trend for both the implanted Al concentrations. The activation energies of these plots are the activation energy for placing an implanted Al atom in a substitutional site, i.e. the electrical activation energy. Activation energies around 1 eV, equal within errors for the two implanted Al concentrations, were found.
New Materials for Semi-Insulating SiC Single Crystal Growth by PVT Method
Authors: Choi Jeong Min , Lee Chae Young , Kim Dae Sung , Park Mi Seon , Jang Yeon Suk , Lee Won Jae , Fan Wei , Qu Hao , Chen Xiu Fang , Xu Xian Gang
Published: July 2019

The present research was focused on the effect of porous graphite plate in TaC-coated crucible on crystal quality and resistivity of semi-insulating SiC crystals. Two SiC crystals grown with/without porous graphite plate in TaC-coated crucible were systematically compared. 6H-SiC polytype was obtained on both crystals regardless of porous graphite plate. The quality of SiC crystal grown using porous graphite plate placed in the TaC-coated crucible was slightly better than SiC crystal without porous graphite plate. SiC crystals having an average resistivity value of about 1×1010 Ωcm were obtained. In the result of COREMA measurement, the use of porous graphite plate tends to obtain wafers with better uniformity in resistivity value.
Improved SiO2/ 4H-SiC Interface Defect Density Using Forming Gas Annealing
Authors: Wirths Stephan , Alfieri Giovanni , Prasmusinto Alyssa , Mihaila Andrei , Kranz Lukas , Bellini Marco , Knoll Lars
Published: July 2019

We investigated the influence of forming gas annealing (FGA) before and after oxide deposition on the SiO2/4H-SiC interface defect density (Dit). For MOS capacitors (MOSCAPs) that were processed using FGAs at temperatures above 1050°C, CV characterization revealed decreased flat band voltage shifts and stretch-out for different sweep directions and frequencies. Moreover, constant-capacitance deep level transient spectroscopy (CC-DLTS) was performed and showed Dit levels below 1012 cm-2eV-1 for post deposition FGA at 1200°C. Finally, lateral MOSFETs were fabricated to analyze the temperature-dependent threshold voltage (Vth) shift.
Surface Effects of Passivation within Mo/4H-SiC Schottky Diodes through MOS Analysis
Authors: Renz A. Benjamin , Shah Vishal Ajit , Vavasour Oliver James , Bonyadi Yeganeh , Baker G.W.C. , Li Fan , Dai Tian Xiang , Walker Marc , Mawby Philip  Andrew , Gammon Peter Michael
Published: July 2019

Passivation treatments applied prior to Mo metallisation on Silicon Carbide (SiC) Schottky rectifier and metal-oxide-semiconductor capacitor (MOSCAP) structures are studied. A control sample and two treatments, comprising of an O2 oxidation and a phosphorus pentoxide (P2O5) deposition, were studied. Electrical characterisation results show that P2O5 treatment improves the homogeneity of the diodes, with the ideality factor reducing to 1.02 and the leakage current reducing by three orders of magnitude to 2×10-5 A/cm2. Furthermore, the SBH was lowered by 0.11 eV and the variance of all the P2O5 treated Schottky characteristics over the batch reduced. Characterisation by X-ray photoelectron spectroscopy (XPS) showed that the stoichiometry, the Si:C ratio, of the SiC below the contact increased from 0.93:1 before treatment to 0.97:1 after P2O5 treatment.
Deep Level Transient Spectroscopy (DLTS) Study of 4H-SiC Schottky Diodes and PiN Diodes
Authors: Zhou Xiang , Pandey Gyanesh , Ghandi Reza , Losee Peter A. , Bolotnikov Alexander , Chow T. Paul
Published: July 2019

We have studied capacitance mode Deep Level Transient Spectroscopy (DLTS) of five 4H-SiC Schottky diode and PiN diode designs. Comparing with previous DLTS studies, we have identified four traps levels, Z1/2, EH1, EH3 and EH5. Additionally, a new trap level, EH1, is prominent in blanket Al+ and B+ high-energy implanted samples but less so in mask-implanted samples. Al+ implantation increases EH3 (associated with silicon vacancy) and EH5, while B+ implantation significantly reduces EH3. The Z1/2 peak (associated with carbon vacancy) is reduced to very low levels after B+ and Al+ implantation.
High-Efficiency Planarization of SiC Wafers by Water-CARE (Catalyst-Referred Etching) Employing Photoelectrochemical Oxidation
Authors: Kida H. , Toh Daisetsu , Bui Pho Van , Isohashi Ai , Ohnishi Ryosuke , Matsuyama Satoshi , Yamauchi Kazuto , Sano Yasuhisa
Published: July 2019

Catalyst-referred etching (CARE) is an abrasive-free and damage-free polishing method that involves applying a catalytic reaction at the contact point of the catalyst surface and workpiece in a chemical solution. An atomically flat silicon carbide (SiC) wafer surface can be obtained by the CARE process. Recently, it was found that water can be used as a chemical solution, even in the case of SiC polishing. However, its current removal rate of 4H-SiC (0001) 4°off-axis substrate is only 2 nm/h and is expected to increase. In this study, the use of photoelectrochemical oxidation in combination with the CARE process using water was investigated, successfully increasing the removal rate up to approximately 100 nm/h.
On the Development of 1700V SiC JBS Diodes in a 6-Inch Foundry
Authors: Yun Nick , Liu Eric , Sung Woong Je , Larrea Anne Sophie , Franca Daniel , Gorczyca Thomas , Bialy Alexander , Collison Wen Li , Prudhomme Jamie , Hung Pui Yee , Valente Sean , Dunn Shannon , Sapp Brian , Hedrick Jeffrey
Published: July 2019

This paper presents the development of 1700V-rated 4H-SiC JBS diodes in the state-of-the-art 6-inch SiC-dedicated foundry, NY-PEMC (New York- Power Electronics Manufacturing Consortium). The critical considerations in developing the SiC JBS diode including the cell optimization, edge termination design, process flow, and unit process developments are discussed in this paper. Static device performances such as forward conduction and reverse blocking behaviors of fabricated 1700V, 20A-rated JBS diode are presented.
Achieving Reduced Specific On-Resistance in 1.2 kV SiC Power MOSFETs at Elevated Temperature
Authors: Han Ki Jeong , Baliga B. Jayant
Published: July 2019

Power MOSFETs operate at elevated temperatures due to self-heating and hot ambient temperatures. This paper analyzes the increase in on-resistance with temperature for 1.2 kV rated 4H-SiC planar MOSFETs. The impact of various structural parameters are studied using analytical models supported by experimental data. This work defines how to achieve a low ratio [Ron(150°C)/Ron(25°C)] by structural optimization of 1.2 kV SiC planar MOSFETs for the first time. It is found that the inversion mode MOSFETs, fabricated by us in a 6 inch commercial foundry, have a lower ratio [Ron(150°C)/Ron(25°C)] than the accumulation mode MOSFETs, due to a better balance of change in channel and bulk mobility with temperature. Compared with typical commercially available MOSFETs, our fabricated accumulation mode and inversion mode MOSFETs exhibit a lower ratio [Ron(150°C)/Ron(25°C)], resulting in superior HF-FOM [RonxQgd] at 150°C.
Design Optimization of 1.2kV 4H-SiC Trench MOSFET
Authors: Dai Tian Xiang , Gammon Peter Michael , Shah Vishal Ajit , Deng Xiao , Jennings Michael R. , Mawby Philip  Andrew
Published: July 2019

In a trench MOSFET structure, p+ trench bottom implant (also called p+ shielding region) is commonly used to protect the gate oxide from high electric field stress, however, if the design and fabrication process are not optimized properly, the p+ shielding region together with n-drift and the p-base region will form a parasitic JFET which severely degrades the on-state performance of the device. This paper presents this parasitic JFET effect with experimental results and the optimization work that has been done to eliminate the parasitic JFET.
Impact of Interface Trap Density of SiC-MOSFET in High-Temperature Environment
Authors: Sato Shintaroh , Masunaga Masahiro , Mori Yuki , Sugii Nobuyuki , Shima Akio
Published: July 2019

We report the physical and electrical characterization of the inversion layer carrier and the shallow interface trap sites with n-and p-channel SiC-MOSFET in terms of high temperature electronics. This work proposes a physical model that explains the difference between Id-Vg measurement result and calculation result supposing the ideal condition with Pao and Sah double ideal in room temperature. The measurement at 500°C confirmed our model so that inversion carrier were thermally excided, they could not be easily trapped by shallow trap sites, and Id-Vg measurement result approached the ideal condition.
Deep Trench Termination Structure with p-Type SiC Layer for Improved Reliability of High Voltage IGBT
Authors: Du Wen Fang , Wang Yao Hua , Jin Rui , Pu Kui , Zhang Wen Hong , Zeng Jun , Darwish Mohamed N. , Liu Jiang , Zhu Tao
Published: July 2019

A 3.3 kV rated Si-SiC hybrid IGBT with Si-based active structure and Si/SiC composite junction edge termination is proposed in this paper. A single deep and wide Si trench, capped with a hetero-epitaxially grown SiC layer, is employed as the edge termination structure. Therefore, the active region can make full use of the mature Si-based IGBT processes and cell structures with high carrier channel mobility and long electron-hole lifetime. Meanwhile the edge termination benefits from the high critical electric field of SiC and its breakdown voltage can easily reach the ideal value with excellent process windows. The ruggedness and reliability of the device can also be significantly improved because the avalanche occurs inside the silicon bulk and is far from the dielectric/semiconductor interface. The excellent characteristics of the edge termination are studied in detail by simulation. It is shown that the proposed edge structure has higher reliability in terms of the hot carrier effects and much less sensitivity to the interface charges in terms of breakdown degradation.
Simulation Study for the Structural Cell Design Optimization of 15kV SiC p-Channel IGBTs
Authors: Tian Xiao Li , Tan Ben , Bai Yun , Hao Ji Long , Yang Cheng Yue , Liu Xin Yu
Published: July 2019

In this paper, the structural cell design optimization of 15kV 4H-SiC p-channel IGBT is performed. The effects of the parameters of JFET region on the blocking voltage and the forward characteristics are analyzed by numerical simulations. The results indicate that the JFET width and JFET region concentration have an important effect on the performance of IGBTs. Based on the simulation structure in this paper, the optimum JFET width is 10μm, and the optimum JFET concentration is 7×1015cm−3. Meanwhile, they should be carefully designed to achieve the best trade-off between the blocking voltage and the forward voltage drop.
Application of Defect Conversion Layer by Solution Growth for Reduction of TSDs in 4H-SiC Bulk Crystals by PVT Growth
Authors: Komatsu Naoyoshi , Mitani Takeshi , Hayashi Yuichiro , Suo Hiromasa , Kato Tomohisa , Okumura Hajime
Published: July 2019

We have developed the bulk growth technique to reduce threading screw dislocations (TSDs) by combining solution growth and PVT growth methods. More than 80 % of TSDs in original seed crystals were successfully converted to Frank defects on basal planes by the solution growth on 4° off C-face with Si-5at.% Ti solvent. After PVT growth on the as-grown surface of the conversion layer, TSDs in the original seed were successfully reduced. The presence of micrometer-size macrosteps in the initial stage of PVT growth is important to continue to propagate the converted Frank defects on basal planes during PVT bulk growth.