scholarly journals New Approaches and Understandings in the Growth of Cubic Silicon Carbide

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5348
Author(s):  
Francesco La Via ◽  
Massimo Zimbone ◽  
Corrado Bongiorno ◽  
Antonino La Magna ◽  
Giuseppe Fisicaro ◽  
...  
Keyword(s):  
Defect Density ◽  
Growth Parameters ◽  
Electrical Characteristics ◽  
Research Activity ◽  
Material Defects ◽  
Bulk Growth ◽  
New Approaches ◽  
High Level ◽  
Cubic Silicon Carbide

In this review paper, several new approaches about the 3C-SiC growth are been presented. In fact, despite the long research activity on 3C-SiC, no devices with good electrical characteristics have been obtained due to the high defect density and high level of stress. To overcome these problems, two different approaches have been used in the last years. From one side, several compliance substrates have been used to try to reduce both the defects and stress, while from another side, the first bulk growth has been performed to try to improve the quality of this material with respect to the heteroepitaxial one. From all these studies, a new understanding of the material defects has been obtained, as well as regarding all the interactions between defects and several growth parameters. This new knowledge will be the basis to solve the main issue of the 3C-SiC growth and reach the goal to obtain a material with low defects and low stress that would allow for realizing devices with extremely interesting characteristics.

3C-SiC Bulk Growth: Effect of Growth Rate and Doping on Defects and Stress

2020 ◽  
Vol 1004 ◽  
pp. 120-125
Author(s):  
Francesco La Via ◽  
Marco Mauceri ◽  
Viviana Scuderi ◽  
Cristiano Calabretta ◽  
Massimo Zimbone ◽  
...  
Keyword(s):  
Growth Rate ◽  
Silicon Substrate ◽  
Doping Concentration ◽  
Defect Density ◽  
Intrinsic Stress ◽  
Growth Effect ◽  
Bulk Growth ◽  
Raman Measurement ◽  
Cubic Silicon Carbide

We report the study of the effect of the growth rate and of the doping on the stress and the defect density of a Cubic Silicon Carbide (3C-SiC) bulk layer grown at low temperature on a silicon substrate. After the growth process, the silicon substrate was melt inside the CVD reactor used for the deposition and then the intrinsic stress was measured by the curvature of the wafer without influence of the thermal stress between silicon and 3C-SiC. A considerable increase of the curvature was observed increasing the doping of the layer. The average stress is compressive and then produces a convex bow. At the same time, the average quality of the grown material deteriorates increasing the doping concentration. Using μ-Raman measurement in cross-section of the 3C-SiC grown samples, it was possible to observe the dependence of the stress and of the quality of the material as a function of the thickness and of the growth rate, due to the variation of the growth rate during the process. In particular, the increase of the growth rate produced both an increase of the stress and a decrease of the material quality. Furthermore, the increase of the doping concentration produced both an increase of the stress and a further deterioration of the crystal quality.

Influence of Processing and of Material Defects on the Electrical Characteristics of SiC-SBDs and SiC-MOSFETs

2010 ◽  
Vol 645-648 ◽  
pp. 655-660 ◽  
Author(s):  
Kenji Fukuda ◽  
Akimasa Kinoshita ◽  
Takasumi Ohyanagi ◽  
Ryouji Kosugi ◽  
T. Sakata ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Defect Density ◽  
Gate Oxide ◽  
The Other ◽  
Electrical Characteristics ◽  
Material Defects ◽  
Processing Defects ◽  
Activation Annealing ◽  
Dislocation Defects

The influences of processing and material defects on the electrical characteristics of large-capacity (approximately 100A) SiC-SBDs and SiC-MOSFETs have been investigated. In the case of processing defects, controlled activation annealing is the most important factor. On the other hand for material defects, the number of epitaxial defects must be decreased to zero for both SBDs and MOSFETs. The dislocation defects in SiC wafers are dangerous for the breakdown voltage of MOSFETs. However, they are not killer defects. If the epitaxial defect density is sufficiently low and the dislocation density is in the order of 10000cm-2, the long- term reliability of the gate oxide at the electric field of 3MV/cm can be guaranteed.

Comparative Studies of the Structural, Electrical and Opto-Electronic Properties of Epitaxial GaAs Layers Grown On Either Si, Ge Or Ge Coated Si Substrates By Mocvd

1987 ◽  
Vol 91 ◽  
Author(s):  
M. Abdul Awai ◽  
El Hang Lee ◽  
Eric Y. Chan ◽  
R.M. Lum ◽  
J.K. Klingert ◽  
...  
Keyword(s):  
Defect Density ◽  
Schottky Diodes ◽  
Optoelectronic Properties ◽  
Electrical Characteristics ◽  
Doping Density ◽  
Si Substrates ◽  
Diode Ideality Factor ◽  
Gaas Films ◽  
Better Than

ABSTRACTWe report the epitaxial growth of GaAs films on bulk Si, Ge and Ge coated Si substrates by MOCVD. This work is directed at comparing the structural, electrical, optical and optoelectronic properties of the GaAs films grown on these substrates. The quality of the GaAs films was evaluated by a number of techniques including X-ray, TEM, RBS, I-V and C-V. We have also obtained good photoresponse for Au-GaAs/Si, Au-GaAs/Ge and Au-GaAs/Ge/Si Schottky diodes at 0.87μm. We have observed significant differences in defect density, strain, crystalline quality, structural order, doping density depth-profile, dark current, diode ideality factor, photoresponse, inter-diffusion and interface structure among these three different structures. The GaAs/Ge structure exhibited the best structural and electrical characteristics of all. The GaAs/Ge/Si structure showed material properties and Schottky diode performance that are better than those of the GaAs/Si stucture. Although Ge and Si both out-diffuse into GaAs, that the out-diffusion of Si into GaAs appears to cause more degradation in the electrical and optoelectronic properties of GaAs.

scholarly journals Investigating the growth of AlGaN/AlN heterostructure by modulating the substrate temperature of AlN buffer layer

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Neha Aggarwal ◽  
Shibin Krishna ◽  
Lalit Goswami ◽  
Shubhendra Kumar Jain ◽  
Akhilesh Pandey ◽  
...  
Keyword(s):  
Buffer Layer ◽  
Defect Density ◽  
Growth Parameters ◽  
Aluminium Content ◽  
Single Crystalline ◽  
Solar Blind ◽  
Aln Buffer ◽  
Growth Quality ◽  
The Impact

AbstractWe have investigated the impact of AlN buffer layer growth parameters for developing highly single crystalline AlGaN films. The low mobility of Al adatoms and high temperature for compound formation are amongst the major causes that affects the growth quality of AlGaN films. Thus, proper optimization need to be carried out for achieving high quality AlGaN due to an augmented tendency of defect generation compared to GaN films. Thus, growth conditions need to be amended to maximize the incorporation ability of adatoms and minimize defect density. So, this study elaborates the growth optimization of AlGaN/AlN/Si (111) heterostructure with varied AlN buffer growth temperature (760 to 800 °C). It was observed that the remnant Al in low temperature growth of AlN buffer layer resist the growth quality of AlGaN epitaxial films. A highly single crystalline AlGaN film with comparatively lowest rocking curve FWHM value (~ 0.61°) and smooth surface morphology with least surface defect states was witnessed when AlN buffer was grown at 780 °C. From the Vegard’s law, the photoluminescence analysis unveils Aluminium composition of 31.5% with significantly reduced defect band/NBE band ratio to 0.3. The study demonstrates good crystalline quality AlGaN film growth with Aluminium content variation between ~ 30–39% in AlGaN/AlN heterostructure on Si(111) substrate leading to a bandgap range which is suitable for next-generation solar-blind photodetection applications.

scholarly journals Atmospheric Pressure Catalytic Vapor Deposition of Graphene on Liquid In and Cu-In Alloy Substrates

Catalysts ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1318
Author(s):  
Maryam A. Saeed ◽  
Ian A. Kinloch ◽  
Brian Derby
Keyword(s):  
Atmospheric Pressure ◽  
Defect Density ◽  
Growth Parameters ◽  
Chemical Vapour ◽  
Growth Conditions ◽  
Growth Time ◽  
Graphene Growth ◽  
Graphene Films ◽  
Reactive Gases

Liquid substrates are great candidates for the growth of high-quality graphene using chemical vapour deposition (CVD) due to their atomically flat and defect free surfaces. A detailed study of graphene growth using atmospheric pressure CVD (APCVD) on liquid indium (In) was conducted. It was found that the effect of the growth parameters on the quality of the graphene produced is highly dependent on the properties of the substrate used. A short residence time of 6.8 sec for the reactive gases led to a high graphene quality, indicating the good catalytic behaviour of In. The role of hydrogen partial pressure was found to be crucial, with monolayer and bilayer graphene films with a low defect density obtained at low PH2 (38.6 mbar), whilst more defective, thicker graphene films with a partial coverage being obtained at high PH2 (74.3 mbar). The graphene deposition was insensitive to growth time as the graphene growth on liquid In was found to self-limit to bilayer. For further investigation, five compositions of Cu-In alloys were made by arc-melting. Graphene was then grown using the optimum conditions for In and the quality of the graphene was found to degrade with increasing Cu wt.%. This work will aid the future optimisation of the growth conditions based upon the substrate’s properties.

Improvement of 4H-SiC Epitaxial Layers Grown on 2o Offcut Si-Face Substrates

2016 ◽  
Vol 858 ◽  
pp. 133-136 ◽  
Author(s):  
Hirokuni Asamizu ◽  
Keiichi Yamada ◽  
Kentaro Tamura ◽  
Chiaki Kudou ◽  
Johji Nishio ◽  
...  
Keyword(s):  
Surface Defect ◽  
Defect Density ◽  
Growth Parameters ◽  
Metal Oxide Semiconductor ◽  
Oxide Semiconductor ◽  
Epitaxial Layers ◽  
Lower Growth ◽  
Wafer Size ◽  
Lower Growth Temperature

The surface quality of epitaxial layers grown on 2° offcut substrates was improved. These substrates require a lower growth temperature and a lower C/Si ratio than their 4° offcut counterparts to suppress macro step bunching. Surface morphology, triangular defect density, and doping uniformity presented a trade-off relationship with respect to growth parameters. The implementation of a low C/Si ratio buffer layer led to a balance between surface defect density, which reached a minimum of 0.2 cm−2, and good doping uniformity on an equivalent wafer size (150 mm). An evaluation of metal–oxide–semiconductor capacitors and Schottky barrier diodes fabricated on 2° offcut epitaxial layers showed that the quality of these epitaxial layers was satisfactory for application in devices.

Heart Rate Recovery Changes during Competition Period in High-Level Basketball Players

2018 ◽  
Vol 1 (80) ◽  
Author(s):  
Audrius Gocentas ◽  
Anatoli Landõr ◽  
Aleksandras Kriščiūnas
Keyword(s):  
Heart Rate ◽  
Heart Rate Recovery ◽  
Team Sports ◽  
Basketball Players ◽  
Coeffi Cients ◽  
Competition Period ◽  
Monitoring Training ◽  
Intense Training ◽  
High Level

Research background and hypothesis. Replete schedule of competitions and intense training are features of contemporary team sports. Athletes, especially the most involved ones, may not have enough time to recover. As a consequence, aggregated fatigue can manifest in some undesirable form and affect athlete’s performance and health.Research aim. The aim of this study was to evaluate the changes in heart rate recovery (HRR) and investigate possible relations with sport-specifi c measures of effi cacy in professional basketball players during competition season.Research methods. Eight male high-level basketball players (mean ± SD, body mass, 97.3 ± 11.33 kg; height 2.02 ± 0.067 m, and age 23 ± 3.12 years) were investigated. The same basketball specifi c exercise was replicated several times from September till April during the practice sessions in order to assess the personal trends of HRR. Heart rate monitoring was performed using POLAR TEAM SYSTEM. Investigated athletes were ranked retrospectively according to the total amount of minutes played and the coeffi cients of effi cacy. Research results. There were signifi cant differences in the trends of HRR between the investigated players. The most effective players showed decreasing trends of HRR in all cases of ranking.Discussion and conclusions. Research fi ndings have shown that the quality of heart rate recovery differs between basketball players of the same team and could be associated with sport-specifi c effi cacy and competition playing time.Keywords: adaptation, autonomic control, monitoring training.

PROFESSORS' PERCEPTION OF SCIENTIFIC ACTIVITY IN THE FACULTY OF MEDICAL SCIENCES OF THE UNIVERSITY OF GUAYAQUIL

2020 ◽  
Vol 8 (10) ◽  
pp. 70-76
Author(s):  
Jorge Daher Nader ◽  
Amelia Patricia Panunzio ◽  
Marlene Hernández Navarro
Keyword(s):  
Scientific Research ◽  
Scientific Activity ◽  
Medical Sciences ◽  
Research Activity ◽  
University Environment ◽  
Empirical Level ◽  
Teachers And Students ◽  
Scientific Nature ◽  
The University

Research is considered a function aimed at obtaining new knowledge and its application for the solution to problems or questions of a scientific nature, The universities framed in the fulfillment of their social function have a complex task given by training a competent professional who assumes research as part of their training and who learns to ask questions that they are able to solve through scientific research.  Scientific research is an indicator of the quality of processes in the university environment, so it must be increased by virtue of the results of the work carried out by research teachers and students the objective of this work is to know the perception of the teachers of the Faculty of Medical Sciences of the University of Guayaquil about the scientific activity. Objective: to know the perception of the teachers of the Faculty of Medical Sciences of the University of Guayaquil about the scientific activity. Methods: theoretical and empirical level were used, a questionnaire with closed questions aimed at knowing the opinions on the research activity in this institution was applied. Result: that of the sample analyzed 309 (39.3%) said they agreed with the training for the writing of scientific articles. 38.6% said they agree with the training on research projects. Conclusion: that teacher’s research should be enhanced to ensure the formation and development of research skills in students.

About Innovative Content of Subject-Oriented Pedagogical Education

2019 ◽  
Vol 28 (10) ◽  
pp. 106-117
Author(s):  
R. M. Asadullin
Keyword(s):  
Teacher Education ◽  
Teacher Training ◽  
Educational Process ◽  
Professional Activity ◽  
Subject Knowledge ◽  
Technological Structure ◽  
State Pedagogical ◽  
High Level ◽  
Competencies Development

The continuous modernization of the education system makes the problems of the quality of teacher training increasingly relevant. Moreover, the measures taken to improve the system of teacher education are largely confined to the introduction of new organizational and managerial mechanisms and practically do not affect the internal content and technological structure of the teacher training process.Modern pedagogical universities are constantly looking for innovative models of training teachers that will be able to solve non-standard social and professional tasks. However, recent studies in this area do not fully take into account the nature of pedagogical activity and conditions of its formation. Thus, the need arises for a special study of the processes and means of updating the content and technologies of teacher training in order to control the level of students’ professional competencies development, as required by educational and professional standards. This means the creation of a special educational system in a pedagogical university, which can provide a harmonious and synchronous mastering by future specialists of both subject knowledge and methods of pedagogical activity.The article provides a theoretical study aimed at identifying key patterns of designing a new content for teacher education, the basis of which is the formation of a future teacher as a subject of his own professional activity. The author describes the experience of using a subject-oriented model of education, implemented at Bashkir State Pedagogical University n.a. M. Akmulla. The effectiveness of this model is confirmed by the high level of students’ mastery of designing methods and constructing the educational process, as well as their positive experience in the implementation of educational activities.

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