Improvement of Repeatability on N-Type 4H-SiC Epitaxial Growth by High Speed Wafer Rotation Vertical CVD Tool

2020 ◽  
Vol 1004 ◽  
pp. 78-83
Author(s):  
Yoshiaki Daigo ◽  
Akio Ishiguro ◽  
Shigeaki Ishii ◽  
Takehiko Kobayashi ◽  
Yoshikazu Moriyama
Keyword(s):  
Carrier Concentration ◽  
High Speed ◽  
Epitaxial Films ◽  
The Other ◽  
Short Term ◽  
Wafer Thickness ◽  
Sic Film ◽  
Sic Films ◽  
Effect Of Surface

N-type 4H-SiC homo-epitaxial films were grown on 150 mm diameter wafers by high speed wafer rotation vertical CVD tool, and effect of surface C/Si ratio on short-term and long-term repeatability of the SiC films was investigated. By tuning of growth condition, high uniform SiC film with in-wafer thickness uniformity of ±2.8 % (1.6 % σ/mean) and carrier concentration uniformity of ±3.1 % (1.9 % σ/mean) was successfully grown at higher introduced C/Si ratio of about 1.80, which corresponds to surface C/Si ratio higher than 1.0 on the whole wafer. This result was comparable to the film grown at lower introduced C/Si ratio of about 1.35, which corresponds to surface C/Si ratio lower than 1.0 on the whole wafer. On the other hand, the films on 13 wafers successively grown at higher introduced C/Si ratio indicated low fluctuation from 1.85 to 3.09 % (σ/mean), and the short-term repeatability of the in-wafer carrier concentration uniformity of the films grown at higher introduced C/Si ratio was improved compared with the films grown at lower introduced C/Si ratio. Additionally, in-wafer carrier concentration uniformity of the films on 171 wafers grown at higher introduced C/Si ratio showed 75 % quartile of 4.26 % (σ/mean), and this result was greatly superior to that of 8.21 % (σ/mean) for the films on 130 wafers grown at lower introduced C/Si ratio.

Repeatability of Epitaxial Growth of n-Type 4H-SiC Films by High Speed Wafer Rotation Vertical CVD Tool

2019 ◽  
Vol 963 ◽  
pp. 101-104 ◽  
Author(s):  
Yoshiaki Daigo ◽  
Akio Ishiguro ◽  
Shigeaki Ishii ◽  
Yoshikazu Moriyama ◽  
Kunihiko Suzuki ◽  
...  
Keyword(s):  
Epitaxial Growth ◽  
Carrier Concentration ◽  
High Speed ◽  
Epitaxial Films ◽  
Short Term ◽  
Gas Nozzle ◽  
Sic Films ◽  
Growth Experiments ◽  
Nozzle Structure

N-type 4H-SiC homo-epitaxial films were grown by high speed wafer rotation vertical CVD tool, and both short term repeatability and long term repeatability of epitaxial growth were investigated. In the short term repeatability investigated by 6 epitaxial wafers chosen from successively grown 12 epitaxial wafers using same recipe, it was found that total variation of thickness and carrier concentration for all measurement points of 6 wafers is 1.44 and 4.64 % respectively, which indicates excellent repeatability as well as high uniform thickness and carrier concentration. In the long term repeatability investigated by a very large number of growth experiments, probability achieving target uniformity of thickness and carrier concentration of the SiC films was increased up to 1.32 times by optimizing gas nozzle structure in gas inlet compared with in the case of conventional gas nozzles. Moreover, adjustment range of C/Si ratio necessary to achieve target uniformity of thickness and carrier concentration of the films was considerably reduced to 22 % by optimized gas nozzles.

Achievement of Low Carrier Concentration of High-Uniformity SiC Films Grown by High Speed Wafer Rotation Vertical CVD Tool

2020 ◽  
Vol 1004 ◽  
pp. 84-90
Author(s):  
Yoshiaki Daigo ◽  
Akio Ishiguro ◽  
Shigeaki Ishii ◽  
Takehiko Kobayashi ◽  
Yoshikazu Moriyama
Keyword(s):  
Carrier Concentration ◽  
High Speed ◽  
Carrier Lifetime ◽  
Lower Sensitivity ◽  
Wafer Thickness ◽  
High Uniformity ◽  
The Mean ◽  
Sic Film ◽  
Sic Films ◽  
Effect Of Surface

N-type 4H-SiC homo-epitaxial films were grown by high speed wafer rotation vertical CVD tool, and effect of surface C/Si ratios on in-wafer uniformity and lower limit of carrier concentration of the SiC films on 150 mm diameter wafers was investigated. From analysis of in-wafer distribution by mapping of whole wafers, it was found that high in-wafer thickness uniformity was obtained for the films grown both at lower introduced C/Si ratio of about 1.35, which corresponds to surface C/Si ratio is lower than 1.0, and at higher introduced C/Si ratio of about 1.80, which corresponds to surface C/Si ratio is higher than 1.0. However, larger fluctuation of the carrier concentration at wafer edge was observed for the film grown at lower introduced C/Si ratio, compared with the film grown at higher introduced C/Si ratio. Lower fluctuation of the carrier concentration for the film grown at higher introduced C/Si ratio is thought to be due to lower sensitivity of carrier concentration on growth temperature, which is observed for the film grown at surface C/Si ratio higher than 1.0. Also, the film grown at higher introduced C/Si ratio showed longer carrier lifetime with higher uniformity, although the film grown at lower introduced C/Si ratio indicated shorter carrier lifetime with lower uniformity. The mean carrier concentration of the films grown at higher introduced C/Si ratio was reduced by two digits compared with those grown at lower introduced C/Si ratio, and low carrier concentration of 1.7 x 1014 cm-3 with high in-wafer uniformity for intentionally doped SiC film grown at higher introduced C/Si ratio was achieved. Based on the results mentioned above, fabrication of thick and low-doped epi layer on 150 mm diameter wafer with high in-wafer uniformity was demonstrated.

Hidden “holes” in the capital of banks and the supply of credit to the real sector of economy

2018 ◽  
pp. 49-68 ◽  
Author(s):  
M. E. Mamonov
Keyword(s):  
Credit Risk ◽  
The Other ◽  
Real Sector ◽  
Capital Management ◽  
Loan Loss ◽  
Short Term ◽  
The Real ◽  
Ex Post ◽  
The One

Our analysis documents that the existence of hidden “holes” in the capital of not yet failed banks - while creating intertemporal pressure on the actual level of capital - leads to changing of maturity of loans supplied rather than to contracting of their volume. Long-term loans decrease, whereas short-term loans rise - and, what is most remarkably, by approximately the same amounts. Standardly, the higher the maturity of loans the higher the credit risk and, thus, the more loan loss reserves (LLP) banks are forced to create, increasing the pressure on capital. Banks that already hide “holes” in the capital, but have not yet faced with license withdrawal, must possess strong incentives to shorten the maturity of supplied loans. On the one hand, it raises the turnovers of LLP and facilitates the flexibility of capital management; on the other hand, it allows increasing the speed of shifting of attracted deposits to loans to related parties in domestic or foreign jurisdictions. This enlarges the potential size of ex post revealed “hole” in the capital and, therefore, allows us to assume that not every loan might be viewed as a good for the economy: excessive short-term and insufficient long-term loans can produce the source for future losses.

Long-Term Growth and Short-Term Policy

1964 ◽  
Vol 29 ◽  
pp. 26-38 ◽  
Author(s):  
W. A. H. Godley ◽  
J. R. Shepherd
Keyword(s):  
Economic Policy ◽  
Balance Of Payments ◽  
The Other ◽  
High Wage ◽  
Short Term ◽  
High Unemployment ◽  
The Government ◽  
Wage Increases

One of the main aims of short-term economic policy in Britain has been to regulate the pressure of demand for labour, and to keep the fluctuations of the unemployment percentage within fairly narrow limits. High unemployment is obviously undesirable; at the other end of the scale, if the pressure of demand for labour is too strong, this tends to lead to excessively high wage increases and to balance of payments difficulties. It is for the Government to decide at what pressure it wishes to run the economy, and to try to keep it there.

Terrorism and Violence

2019 ◽  
pp. 138-180
Author(s):  
Douglas Allen
Keyword(s):  
Complex Analysis ◽  
General Analysis ◽  
The Other ◽  
Short Term ◽  
Absolute Truth ◽  
Relative Truth ◽  
Central Concern ◽  
The Us ◽  
The Status

Ever since 9/11 in the US and 26/11 in India, terrorism has been a central concern. Gandhi is generally assumed to be of little value when confronting terrorism today. At best, he is irrelevant; at worst, he is complicit and contributes to the crisis since he opposes necessary violent responses. This essay argues that while Gandhi does not have all of the answers for dealing with terrorism today, he provides us with a complex analysis essential for understanding and responding to the multidimensional structural crisis. After analyzing the nature and meaning of terrorism, we focus on the following topics: Gandhi’s interactions with terrorists; his means-ends analysis and his short-term and long-term preventative approaches to terrorism; his analysis of absolute truth and relative truth in approaching terrorism; and his general analysis of the status of “the other” in transforming our relations with violent, terrorizing, and terrorized others.

Antimicrobial Applications of Nanoparticles

2022 ◽  
pp. 269-288
Author(s):  
Ayesha Kanwal ◽  
Zeeshan Ahmad Bhutta ◽  
Ambreen Ashar ◽  
Ashar Mahfooz ◽  
Rizwan Ahmed ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Side Effects ◽  
Antibacterial Agent ◽  
Antibacterial Agents ◽  
The Other ◽  
Drug Resistant ◽  
Short Term ◽  
Human Mortality ◽  
Recent Developments

Human mortality due to drug-resistant infections is becoming more prevalent in our society. Antibiotics are impotent due to abuse and/or misuse, leading to new, more expensive, and more effective medicines and treatments. Therefore, it causes many short-term and long-term side effects in the patient. On the other hand, nanoparticles have exhibited antibacterial activity against various pathogens due to their small size and ability to destroy cells by various mechanisms. Unlike antibiotics for the treatment of patients' diseases and infections, nanomaterials provide an exciting way to limit the growth of microorganisms due to infections in humans. This has led to the development of a number of nanoparticles as active antibacterial agents. Therefore, the authors have carefully reviewed the recent developments in the use of nanomaterials for antibacterial applications and the mechanisms that make them an effective alternate antibacterial agent.

A dynamic and robust image processing based method for measuring the yarn diameter and its variation

2014 ◽  
Vol 84 (18) ◽  
pp. 1948-1960 ◽  
Author(s):  
Mohamed Eldessouki ◽  
Sayed Ibrahim ◽  
Jiři Militky
Keyword(s):  
High Speed ◽  
Dynamic Change ◽  
Effective Property ◽  
Periodic Variation ◽  
Short Term ◽  
Reasonable Time ◽  
Yarn Diameter ◽  
Fabric Structure ◽  
Robust Image

The yarn diameter is an effective property in determining fabric structure and processing settings. There are different systems of measuring the yarn diameter; among them is the image analysis of the yarn’s microscopic images. This method is considered to be more precise than other methods, but it is “static” in nature as it measures the property at scattered intervals and does not reflect the continuous variation of the yarn diameter. The goal of the current work is to measure the yarn diameter and its variation over a long length of yarn at fixed intervals to consider the “dynamic” change in the property. To achieve this goal, a high-speed camera (HSC) with a proper magnification was used to capture the images of the yarn and a new robust algorithm was developed to analyze the massive amount of yarn pictures in a reasonable time. The collected data for the yarn diameter were analyzed and compared to the results of the commercial Uster Evenness Tester IV. The results of the HSC were very comparable to the results of Uster and they were able to detect the short-term, the long-term, and the periodic variation of the yarn diameter.

scholarly journals Entrepreneurship Education with Companies: Teachers Organizing School-Company Interaction

2020 ◽  
Vol 10 (10) ◽  
pp. 268
Author(s):  
Kaarina Sommarström ◽  
Elena Oikkonen ◽  
Timo Pihkala
Keyword(s):  
Basic Education ◽  
School Principals ◽  
Education Level ◽  
The Other ◽  
School Level ◽  
Structured Interviews ◽  
School Teachers ◽  
Short Term ◽  
Entrepreneurial Learning

Previous research into entrepreneurial learning has focused mainly on defining its aims; however, there seems to be little discussion on understanding the barriers or incentives involved when carrying out the pedagogical solutions that would enable entrepreneurial learning. In this study, we examine basic education level schools’ cooperation with outside partners, especially from the school principals’ and teachers’ viewpoints. The study aims to understand the perspectives of teachers and principals on planning and organizing school-company interaction. To do this, content analysis was used in this qualitative study. The data were collected via semi-structured interviews with school teachers and principals, involving a total of 35 people working in basic education. The findings of the study show that principals and teachers intentionally select long-term cooperation methods to meet the aims of entrepreneurial learning. On the other hand, teachers that have chosen to apply short-term school-company cooperation methods have highlighted the ease of these methods rather than learning. Finally, our findings suggest that planning and organizing entrepreneurial learning would benefit from school-level commitment where collaboration between teachers and between teachers and company representatives is valued. We believe that would lead to more satisfied teachers and longer-term school-company cooperation, and also believe that short-term school-company cooperation methods would better meet the aims of entrepreneurial learning.

Effects of Proactive Interference and Rehearsal on the Primary and Secondary Components of Short-Term Retention

1975 ◽  
Vol 27 (1) ◽  
pp. 47-62 ◽  
Author(s):  
M. T. Turvey ◽  
Robert A. Weeks
Keyword(s):  
Proactive Interference ◽  
Primary Memory ◽  
The Other ◽  
Secondary Memory ◽  
Retention Function ◽  
Short Term ◽  
Retention Period ◽  
Term Retention ◽  
Proactive Effects

Under the conditions of the distractor paradigm, short-term retention declines to a minimum in a very brief period. The rapid forgetting can be said to reflect the declining contribution of the short-term store or primary memory and the asymptote can be taken as a measure of the contribution of the long-term store or secondary memory. It was shown that manipulating proactive effects by varying the recency of prior material affected only the primary memory component of the short-term retention function. On the other hand manipulating the difficulty of the subsidiary task performed during the retention period with proactive effects held constant affected both the primary and the secondary components. The results were discussed with respect to the relation between the two memory components and the idea that proactive effects are limited to long-term store.

scholarly journals Influence of Progesterone-Treatment Length and eCG Administration on Appearance of Estrus Behavior, Ovulatory Success and Fertility in Sheep

Animals ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 9 ◽  
Author(s):  
Paula Martinez-Ros ◽  
Alejandro Rios-Abellan ◽  
Antonio Gonzalez-Bulnes
Keyword(s):  
Drug Release ◽  
Chorionic Gonadotrophin ◽  
Ovulation Rate ◽  
The Other ◽  
Short Term ◽  
Treatment Length ◽  
Progesterone Secretion ◽  
Progesterone Treatment ◽  
Estrus Behavior

The present study characterizes, for sheep, the occurrence and timing of the onset of estrus behavior and ovulation and the yields obtained (ovulation rate, progesterone secretion, and fertility) after Controlled Internal Drug Release (CIDR) insertion for five, six, seven, or fourteen days, with or without equine chorionic gonadotrophin (eCG) in ewes of the Segureña meat breed. All the treatments showed above 80% of females displaying estrus, but the onset of estrus was earlier and more synchronized when using eCG and, among groups with eCG, onset of estrus was earlier in the sheep treated for 14 days than in the short-term treatments (p < 0.05 for all). Administration of eCG after either short- or long-term treatments assured the occurrence of fertile ovulations in all the animals. Conversely, ovulatory success without eCG was found to be dependent on treatment length, with a high percentage of animals ovulating after five days of treatment (83.3%) and very low percentages after treatment for six or seven days (40% and 20%, respectively). Ovulation rate and progesterone secretion were similar among animals ovulating, but ovulation failures predetermined the fertility yields obtained in response to the treatments. Hence, the best results were found after treatment for 14 days plus eCG, and for 5 days without eCG (83.3 for both, p < 0.05 when compared to the other groups with different treatment lengths and with or without eCG).

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