The influence of low partial pressures of oxygen on the rhythm in the growth rate of theAvena coleoptile

Planta ◽  
1963 ◽  
Vol 60 (3) ◽  
pp. 261-273 ◽  
Author(s):  
Malcolm B. Wilkins ◽  
Diana M. Warren
Keyword(s):  
Growth Rate ◽  
Partial Pressures

A polycentric growth model of gallium arsenide epitaxial layers from the gas phase with simultaneous diffusion, adsorption and chemical reaction

1988 ◽  
Vol 53 (12) ◽  
pp. 2995-3013
Author(s):  
Emerich Erdös ◽  
Jindřich Leitner ◽  
Petr Voňka ◽  
Josef Stejskal ◽  
Přemysl Klíma
Keyword(s):  
Growth Rate ◽  
Gallium Arsenide ◽  
Epitaxial Growth ◽  
Gas Phase ◽  
Surface Reaction ◽  
Quantitative Description ◽  
The Other ◽  
Rate Equations ◽  
Impact Interaction ◽  
Partial Pressures

For a quantitative description of the epitaxial growth rate of gallium arsenide, two models are proposed including two rate controlling steps, namely the diffusion of components in the gas phase and the surface reaction. In the models considered, the surface reaction involves a reaction triple - or quadruple centre. In both models three mechanisms are considered which differ one from the other by different adsorption - and impact interaction of reacting particles. In every of the six cases, the pertinent rate equations were derived, and the models have been confronted with the experimentally found dependences of the growth rate on partial pressures of components in the feed. The results are discussed with regard to the plausibility of individual mechanisms and of both models, and also with respect to their applicability and the direction of further investigations.

Exploring SiC Growth Limitation of Vapor-Liquid-Solid Mechanism when Using Two Different Carbon Precursors

2013 ◽  
Vol 740-742 ◽  
pp. 323-326
Author(s):  
Kassem Alassaad ◽  
François Cauwet ◽  
Davy Carole ◽  
Véronique Soulière ◽  
Gabriel Ferro
Keyword(s):  
Growth Rate ◽  
High Growth ◽  
High Growth Rate ◽  
Carbon Precursor ◽  
Growth Limitation ◽  
Vapor Liquid Solid ◽  
Partial Pressures ◽  
Vapor Liquid Solid Mechanism ◽  
Vls Growth ◽  
Vapor Liquid

Abstract. In this paper, conditions for obtaining high growth rate during epitaxial growth of SiC by vapor-liquid-solid mechanism are investigated. The alloys studied were Ge-Si, Al-Si and Al-Ge-Si with various compositions. Temperature was varied between 1100 and 1300°C and the carbon precursor was either propane or methane. The variation of layers thickness was studied at low and high precursor partial pressure. It was found that growth rates obtained with both methane and propane are rather similar at low precursor partial pressures. However, when using Ge based melts, the use of high propane flux leads to the formation of a SiC crust on top of the liquid, which limits the growth by VLS. But when methane is used, even at extremely high flux (up to 100 sccm), no crust could be detected on top of the liquid while the deposit thickness was still rather small (between 1.12 μm and 1.30 μm). When using Al-Si alloys, no crust was also observed under 100 sccm methane but the thickness was as high as 11.5 µm after 30 min growth. It is proposed that the upper limitation of VLS growth rate depends mainly on C solubility of the liquid phase.

In Situ Spectroscopic Ellipsometry Study of SiC Oxidation at Low Oxygen-Partial-Pressures

2010 ◽  
Vol 645-648 ◽  
pp. 813-816 ◽  
Author(s):  
Keiko Kouda ◽  
Yasuto Hijikata ◽  
Hiroyuki Yaguchi ◽  
Sadafumi Yoshida
Keyword(s):  
Growth Rate ◽  
Spectroscopic Ellipsometry ◽  
Reaction Rate ◽  
Oxidation Process ◽  
Early Stage ◽  
Oxide Thickness ◽  
Oxide Growth ◽  
Low Oxygen ◽  
Partial Pressures

We have investigated the oxidation process of SiC (000-1) C-face at low oxygen partial pressures using an in-situ spectroscopic ellipsometry. The oxide growth rate decreased steeply at the early stage of oxidation and then slowly decreased with increasing oxide thickness. The initial oxide growth rate was almost proportional to the oxygen　partial　pressure for both the polar directions. This result suggests that the initial interfacial reaction rate is constant regardless of the concentration of oxidants reaching the interface.

scholarly journals Growth of Streptococcus faecalis under High Hydrostatic Pressure and High Partial Pressures of Inert Gases

1968 ◽  
Vol 52 (5) ◽  
pp. 810-824 ◽  
Author(s):  
Wallace O. Fenn ◽  
Robert E. Marquis
Keyword(s):  
Growth Rate ◽  
Nitrous Oxide ◽  
Lactic Acid ◽  
Hydrostatic Pressure ◽  
Inert Gases ◽  
Inhibitory Potency ◽  
Streptococcus Faecalis ◽  
Volume Increase ◽  
Partial Pressures ◽  
Gas Pressures

Growth of Streptococcus faecalis in a complex medium was inhibited by xenon, nitrous oxide, argon, and nitrogen at gas pressures of 41 atm or less. The order of inhibitory potency was: xenon and nitrous oxide > argon > nitrogen. Helium appeared to be impotent. Oxygen also inhibited streptococcal growth and it acted synergistically with narcotic gases. Growth was slowed somewhat by 41 atm hydrostatic pressure in the absence of narcotic gases, but the gas effects were greater than those due to pressure. In relation to the sensitivity of this bacterium to pressure, we found that the volume of cultures increased during growth in a volumeter or dilatometer, and that this dilatation was due mainly to glycolysis. A volume increase of 20.3 ± 3.6 ml/mole of lactic acid produced was measured, and this value was close to one of 24 ml/mole lactic acid given for muscle glycolysis, and interestingly, close to the theoretic volume increase of activation calculated from the depression of growth rate by pressure.

A Study on unique Crystal Morphology observed in the Polycrystalline Copper CVD

2001 ◽  
Vol 672 ◽  
Author(s):  
Yuneng Chang ◽  
Yalian Chen ◽  
Kuanhon Chen
Keyword(s):  
Growth Rate ◽  
Water Vapor ◽  
Whisker Growth ◽  
Chemical Vapor ◽  
Axial Direction ◽  
Competitive Growth ◽  
Partial Pressures ◽  
Chromium Acetylacetonate ◽  
Pressure Chemical ◽  
Axial Growth

ABSTRACTNanostructure copper whisker growth was observed in an atmospheric pressure chemical vapor deposition (CVD) system, which used copper acetylacetonate vapor and 10-15 torr of water vapor as reactants, with 0.04-0.10 torr of chromium acetylacetonate vapor added as growth promoting catalyst. Water vapor initiated nucleation of these helical, spiral shape Cu(111) and (200) polycrystalline whiskers. While chromium acetylacetonate accelerated the growth rate. Copper whiskers had radii from 0.1 to 0.24 μm, lengths from 1 to 10 μm, and distribution density of 0.20-3.6 whiskers/μm2. Dependence of such whisker characteristics on temperature, partial pressures of H2O and chromium acetylacetonate was used to construct a kinetic model. From the Arrhenius equation, data analysis for whisker growth rate against deposition temperature showed that the activation energy for whisker growth along radial direction is 12.4 kcal/mol, and 19.6 kcal/mol for growth along axial direction. Based on such data and SEM observations, a base vapor-liquid-solid (VLS) model involving BCF theory was proposed to describe the governing mechanism for the axial growth. This model interpreted the competitive growth phenomena in both radial and axial directions, and controlling steps for radial and axial growth being assigned to mass transfer and surface reaction, respectively.

Aluminum Nitride Crystal Growth by Halide Vapor Transport Epitaxy

2002 ◽  
Vol 743 ◽  
Author(s):  
V. L. Tassev ◽  
D. F. Bliss ◽  
D. Weyburne ◽  
J. S. Bailey ◽  
S.-Q. Wang
Keyword(s):  
Growth Rate ◽  
Aluminum Chloride ◽  
Gas Flow ◽  
Fused Silica ◽  
Vapor Transport ◽  
Effect Of Temperature ◽  
Crystalline Layer ◽  
Rocking Curve ◽  
Partial Pressures ◽  
Oxygen Contamination

AbstractHalide vapor transport epitaxy (HVTE) is demonstrated for growth of AlN layers with thickness up to 50 μm at deposition rates up to 60 μm/h. The HVTE process uses an aluminum chloride amine adduct as the aluminum source of both aluminum and nitrogen. This new technique eliminates the main difficulties of the conventional hydride VPE growth, where aluminum oxidation and the strong reactivity of aluminum chloride with fused silica create the potential for oxygen contamination. This study shows the effect of temperature, gas flow velocities, and reactor pressure on the growth rate and layer quality. It is found that the growth rate and the layer quality strongly depend on the gas ratio. The species of carrier gas, the flow rates and partial pressures can be used as tools to optimize growth rate and to avoid any etching effects resulting from reverse chemical reactions. The crystalline layer quality as determined by x-ray rocking curve measurement shows FWHM of 300–900 and 500–1300 arc-sec for (002) and (102) planes, respectively.PACS: 81.05.Ea; 81.15.Kk; 68.55.Jk.

A dual site growth model of gallium arsenide epitaxial layers from the gas phase

1987 ◽  
Vol 52 (5) ◽  
pp. 1131-1159
Author(s):  
Emerich Erdös ◽  
Jindřich Leitner ◽  
Petr Voňka ◽  
Josef Stejskal ◽  
Přemysl Klíma
Keyword(s):  
Growth Rate ◽  
Gallium Arsenide ◽  
Gas Phase ◽  
Quantitative Description ◽  
The Other ◽  
Rate Equations ◽  
Partial Pressures ◽  
The Individual ◽  
Rate Controlling Step ◽  
Dual Site

For a quantitative description of the epitaxial growth rate of gallium arsenide, a model is proposed including two rate controlling steps. One of these steps is the diffusion of gaseous components between the gas phase and the epitaxial layer surface, and the other step is of chemical nature, i.e. either the surface reaction or adsorption or desorption of one of the gaseous components. In the model considered, an active dual site is involved in the second rate controlling step, and twelve mechanisms are proposed for which the pertinent rate equations are derived. The individual mechanisms differ one from the other not only by the kind of the rate controlling step but also by the occupation of the dual site, viz. in the both direct and reversed direction. The proposed model is confronted with the dependences of the growth rate on partial pressures of components in the feed found by experiment. The results are discussed with regard to the possibility of individual mechanisms and of the model as a whole, and also with respect to their applicability and to the direction of further investigations.

scholarly journals Thermal plasticity of growth and chain formation of the dinoflagellates Alexandrium affine and Alexandrium pacificum with respect to ocean acidification

ALGAE ◽  
2021 ◽  
Vol 36 (4) ◽  
pp. 285-298
Author(s):  
Chung Hyeon Lee ◽  
Juhee Min ◽  
Hyun-Gwan Lee ◽  
Kwang Young Kim
Keyword(s):  
Growth Rate ◽  
Chain Length ◽  
Functional Traits ◽  
Elevated Pco2 ◽  
Marine Phytoplankton ◽  
Chain Formation ◽  
Thermal Plasticity ◽  
Partial Pressures ◽  
Pco2 Condition ◽  
Cardinal Temperatures

The amount of CO2 absorbed by the oceans continues to rise, resulting in further acidification, altering some functional traits of phytoplankton. To understand the effect of elevated partial pressures of CO2 (pCO2) on functional traits of dinoflagellates Alexandrium affine and A. pacificum, the cardinal temperatures and chain formation extent were examined under two pCO2 (400 and 1,000 μatm) over the range of temperature expected to be associated with growth. The growth rate and chain formation extent of A. affine increased with higher pCO2, showing significant changes in cardinal temperatures and a substantial increase in middle chain-length (4‒8 cells) fractionation under elevated pCO2 condition. By contrast, there were no significant differences in specific growth rate and any chain-length fractionation of A. pacificum between ambient and elevated pCO2 conditions. The observed interspecies variation in the functional traits may reflect differences in ability of species to respond to environmental change with plasticity. Moreover, it allows us to understand the shifting biogeography of marine phytoplankton and predict their phenology in the Korea Strait.

Sign in / Sign up

Export Citation Format

Share Document