Behavior of Particles in the Growth Reactor and their Effect on Silicon Carbide Epitaxial Growth

2012 ◽  
Vol 717-720 ◽  
pp. 153-156 ◽  
Author(s):  
Tawhid Rana ◽  
Hai Zheng Song ◽  
M.V.S. Chandrashekhar ◽  
Tangali S. Sudarshan
Keyword(s):  
Silicon Carbide ◽  
Epitaxial Growth ◽  
Substrate Surface ◽  
Epitaxial Films ◽  
The Other ◽  
Size And Shape ◽  
Other Hand ◽  
Induced Defects ◽  
Shape Of Particles

Formation of particles and their effect on SiC epitaxial growth in the CVD reactor is investigated. Particle induced defects in the epilayer at different gas decomposition conditions are discussed. A higher number of pits with larger diameters are observed in the epilayer for conditions where gases decompose later in the gas injector tube (i.e. nearer to the substrate). On the other hand, the number and size of these pits reduce for the condition where gas decomposes earlier in the tube. To investigate the effect of particles during the growth, various particles with different size, shape and compositions are intentionally placed on the substrate surface before epitaxial films are grown. Samples are mapped and compared at similar locations in the pre-growth, post growth and post-etch (by molten KOH) conditions. It is found that the nature of particle induced defects depends primarily on size and shape of particles.

Leibniz On Form and Matter

1997 ◽  
Vol 2 (3) ◽  
pp. 326-351 ◽  
Author(s):  
Daniel Garber
Keyword(s):  
Physical World ◽  
The Other ◽  
Middle Years ◽  
Size And Shape ◽  
Mechanical Philosophy ◽  
Other Hand

AbstractThis paper discusses the Aristotelian notions of matter and form as they are treated in the philosophy of Leibniz. The discussion is divided into three parts, corresponding to three periods in Leibniz's development. In the earliest period, as exemplified in a 1669 letter to his former mentor Jakob Thomasius, Leibniz argues that matter and form can be given straightforward interpretations in terms of size and shape, basic categories in the new mechanical philosophy. In Leibniz's middle years, on the other hand, as exemplified in the Discourse on Metaphysics and the correspondence with Arnauld, Leibniz seems to hold a more orthodox Aristotelian view of matter and form as the constituents of the corporeal substances that ground the reality of the physical world. In Leibniz's latest years, as discussed in the letters with Des Bosses, matter and form enter once again in connection with the vinculum substantiale, the substantial bond that is supposed to bind monads together to form corporeal substances.

Role of Cl/Si Ratio in the Low-Temperature Chloro-Carbon Epitaxial Growth of SiC

2013 ◽  
Vol 740-742 ◽  
pp. 205-208
Author(s):  
Galyna Melnychuk ◽  
Siva Prasad Kotamraju ◽  
Yaroslav Koshka
Keyword(s):  
Growth Rate ◽  
Low Temperature ◽  
Epitaxial Growth ◽  
Growth Process ◽  
Growth Conditions ◽  
The Other ◽  
Additional Increase ◽  
Other Hand

In order to understand the influence of the Cl/Si ratio on the morphology of the low-temperature chloro-carbon epitaxial growth, HCl was added during the SiCl4/CH3Cl growth at 1300°C. Use of higher Cl/Si ratio allowed only modest improvements of the growth rate without morphology degradation, which did not go far beyond what has been achieved previously by optimizing the value of the input C/Si ratio. On the other hand, when the epitaxial growth process operated at too low or too high values of the input C/Si ratio, i.e., outside of the window of good epilayer morphology, any additional increase of the Cl/Si ratio caused improvement of the epilayer morphology. It was established that this improvement was due to a change of the effective C/Si ratio towards its intermediate values, which corresponded to more favorable growth conditions.

Epitaxial Growth of Cadmium Sulfide Films Evaporated Upon Mica

1967 ◽  
Vol 25 ◽  
pp. 346-347
Author(s):  
G. Shimaoka ◽  
A. S. Walch
Keyword(s):  
Cadmium Sulfide ◽  
Epitaxial Growth ◽  
Substrate Surface ◽  
The Other ◽  
Average Thickness ◽  
Direct Transmission ◽  
Mica Surface ◽  
Mica Substrate ◽  
Transmission Electron ◽  
Reflection Electron Diffraction

It has been reported that thin cadmium sulfide films evaporated onto a glass substrate show strong preferred orientation with the (0001) plane parallel to the substrate surface. Escoffery has reported highly oriented CdS crystals evaporated onto mica heated at 250°C. The purpose of the present experiment is to study the structure and orientation of thin CdS films evaporated onto a mica substrate as a function of the substrate temperature and to find the temperature of optimum epitaxial growth.Cadmium sulfide was evaporated onto a freshly cleaved mica surface heated at various temperatures between 25° and 500°C in a vacuum of ∼ 1 × 10−4 torr. Average thickness of the evaporated films was about 500Å. The evaporated specimens were divided into two parts. The first part was examined by reflection electron diffraction for several different azimuthal positions of the deposits on the mica surface. The other part was used for direct transmission electron microscopy.

Ferromagnetic domains in CrBr3, investigated with a liquid helium magnetic specimen stage

1978 ◽  
Vol 36 (1) ◽  
pp. 464-465
Author(s):  
H. Möllner ◽  
M. Schönauer ◽  
E.M. Hörl
Keyword(s):  
Magnetic Field ◽  
Liquid Helium ◽  
Curie Point ◽  
The Other ◽  
Horizontal Magnetic Field ◽  
Size And Shape ◽  
Other Hand ◽  
Ferromagnetic Domains ◽  
Electron Microscopical ◽  
Foil Orientation

In continuation of the electron microscopical work on CrBr3 done by Matricardi et. al. we have applied a special type of liquid helium specimen stage, which has permitted application of a horizontal magnetic field in the specimen region. During observation of the specimen we have been able to apply fields up to 60 Oe, without observation fields up to 600 Oe.In general the observations of Matricardi et.al. have been confirmed, especially the contrast, size and shape of the domains, their non-appearance in in-focus micrographs and micrographs taken above the Curie point. On the other hand occasional regions of the foil, where the contrast disappears (Fig. 1a] are not thought to be chemical inhomogeneities. Such regions can exhibit strong domain contrast if the foil orientation changes slightly, as in our case by the thermal strains occuring in warming-up the specimen to approx. 60 K and cooling it down again.

Bulk Growth of Large Area SiC Crystals

2016 ◽  
Vol 858 ◽  
pp. 5-10 ◽  
Author(s):  
Adrian R. Powell ◽  
Joseph J. Sumakeris ◽  
Yuri Khlebnikov ◽  
Michael J. Paisley ◽  
R.T. Leonard ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Dislocation Density ◽  
Epitaxial Growth ◽  
Substrate Surface ◽  
Large Diameter ◽  
Vapor Transport ◽  
Physical Vapor Transport ◽  
Large Area ◽  
Substrate Quality ◽  
Bulk Growth

The growth of large diameter silicon carbide (SiC) crystals produced by the physical vapor transport (PVT) method is outlined. Methods to increase the crystal diameters, and to turn these large diameter crystals into substrates that are ready for the epitaxial growth of SiC or other non homogeneous epitaxial layers are discussed. We review the present status of 150 mm and 200 mm substrate quality at Cree, Inc. in terms of crystallinity, dislocation density as well as the final substrate surface quality.

scholarly journals Comparative Actualistic Study Hints at Origins of Intriguing Miocene “Coprolites” of Poland

2021 ◽  
Author(s):  
Tomasz Brachaniec ◽  
Dorota Środek ◽  
Dawid Surmik ◽  
Robert Niedźwiedzki ◽  
Georgios L. Georgalis ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Mechanical Deformation ◽  
The Other ◽  
Size And Shape ◽  
Other Hand ◽  
Shell Fragment ◽  
The Subject ◽  
Food Residues

Abstract Excrement-shaped siderite masses have been the subject of much controversy. They have been variously interpreted either as being coprolites, cololites or pseudofossils created by mechanical deformation of plastic sediment. Here we report excrement-shaped ferruginous masses recovered from the Miocene of the Turów mine in south-western Poland. Mineralogical, geochemical, petrographic and microtomographical analyses indicate that these masses consist of siderite and iron oxide rather than phosphate, and rarely contain recognizable food residues, which may suggest abiotic origins of these structures. On the other hand, evidence in support of a faecal origin include: (i) the presence of two distinct morphotypes differing in size and shape, (ii) the limited quantity of specimens, (iii) the presence of rare hair-like structures or coalified inclusions and (iv) the presence of fine striations on the surface. Importantly, comparative actualistic studies of Recent vertebrate feces show overall resemblance of the first morphotype (sausage-shaped with rare coalified debris) to excrements of testudinoid turtles (Testudinoidea), whose shell fragment was found in the investigated locality. The second morphotype (rounded to oval-shaped with hair-like structures), in turn, is similar to the feces of some snakes (Serpentes), the remains of which were noted in the Miocene of the neighborhood areas.

Effects of Metal Buffer Layer on the Epitaxial Growth of YBa2Cu3O7-y. Superconducting Films by Dipping-Pyrolysis Process

1995 ◽  
Vol 401 ◽  
Author(s):  
T. Manabe ◽  
I. Yamaguchi ◽  
S. Nakamura ◽  
W. Kondo ◽  
S. Mizuta ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Epitaxial Growth ◽  
Buffer Layer ◽  
Annealing Temperature ◽  
Superconducting Films ◽  
The Other ◽  
Pyrolysis Process ◽  
Ybco Films ◽  
Other Hand ◽  
Metal Layers

AbstractSuperconducting Yba2Cu3O7 -x(YBCO) films were prepared by dipping-pyrolysis process on SrTiO3 (001) or on MgO (001) substrates covered with a metal (Au or Ag) buffer layer, and the effects of these metal layers on the growth of YBCO films were investigated. Epitaxial growth of YBCO was found to be suppressed by the Au buffer layer, which crystallized to exhibit (111) orientation, after heat treatment at 700°C and higher. On the other hand, epitaxial YBCO films were obtained starting with Ag buffer layer by heat treatment at 700°C and higher, after which most of Ag was accumulated to particles. It was also found that the annealing temperature required for the epitaxial growth of YBCO films on MgO was lowered to 850°C by adopting the Ag buffer layer.

scholarly journals Size and shape ideophones in Nembe a phonosemantic analysis.pdf

1988 ◽  
Vol 19 (1) ◽  
pp. 94-99
Author(s):  
Omen N. Maduka
Keyword(s):  
The Other ◽  
Direct Connection ◽  
Field Representation ◽  
Size And Shape ◽  
Other Hand ◽  
Multiple Field

In Nembe, ideophones, as in symbolic words in all languages in general, there is direct connection between sounds and the meanings they convey. For Nembe ideophones describing the fields of size and shape. there are peculiar strategies for accomplishing this connection. For size', medial alveolars as well as vowels in the narrow set are used for smallness, while medial velars and vowels in the wide set are used for largeness. For shape, on the other hand, consonant and vowel melodies are used rather than single phonic units. A sequence of three different consonants invariably refers to crooked shape while a sequence of three consonants ending in two identical liquids refers to straight shape, etc. However, this whole neat pattern is complicated 'by the existence of hierarchies of phonosemantic suggestiveness whereby certain phonosemantic units displace others away from their legitimate values, leading to both the ability of otherwise opposing psychomorphs to get into construction and the ability of simultaneous multiple field representation by ideophones.

Kinetics, Microstructure And Mechanisms of Ion Beam Induced Epitaxial Crystallization of Semiconductors.

1985 ◽  
Vol 51 ◽  
Author(s):  
R.G. Elliman ◽  
J.S. Williams ◽  
D.M. Maher ◽  
W.L. Brown
Keyword(s):  
Activation Energy ◽  
Simple Model ◽  
Epitaxial Growth ◽  
Ion Beam ◽  
The Other ◽  
Thermally Induced ◽  
Substrate Orientation ◽  
Epitaxial Crystallization ◽  
Temperature Range ◽  
Other Hand

ABSTRACTIon-beam induced epitaxy is shown to be essentially athermal over the temperature range 200-400°C, and to exhibit no dependence on substrate orientation and little dependence on doping in this regime. On the other hand, the formation and propagation of defects during growth and the interaction of the advancing crystal-amorphous interface with implanted impurities is essentially identical for both thermally induced and ion-beam induced epitaxy. These observations lead to a simple model for ion-beam induced epitaxial crystallization in which epitaxial growth is nucleated by defects generated at, or near, the crystal-amorphous interface by the ion beam. Comparisons of ion-beam induced epitaxy and thermally induced epitaxy suggest that the 2.7 eV activation energy associated with the latter process is dominated by a 2.0 eV nucleation step.

A study of cometary eruptions through OH radio-lines

1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró
Keyword(s):  
Short Duration ◽  
Growth Curves ◽  
The Other ◽  
Initial Mass ◽  
Radio Lines ◽  
Other Hand ◽  
Sudden Rise

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.

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