A dual equilibrium diffusion model for epitaxial growth of gallium arsenide layers from the gas phase and an a priori computation of growth rates

1984 ◽  
Vol 49 (11) ◽  
pp. 2425-2436 ◽  
Author(s):  
Emerich Erdös ◽  
Petr Voňka ◽  
Josef Stejskal ◽  
Přemysl Klíma
Keyword(s):  
Gallium Arsenide ◽  
Epitaxial Growth ◽  
Gas Phase ◽  
Growth Rates ◽  
Diffusion Coefficients ◽  
A Priori ◽  
Boundary Layer Theory ◽  
View Point ◽  
Chemical Equilibria ◽  
Rate Controlling Step

A model is proposed and quantitatively treated of epitaxial growth of gallium arsenide layers, where the rate controlling step consists in the diffusion of reactants through a stagnant gas film adhering to the substrate, and where chemical equilibria are established between the reactants in the main gas stream and at the surface of substrate. The boundary layer theory is applied to the hydrodynamic part of the model which is simplified by introducing a mean effective film thickness, and the system of Ga-As-Cl-H is reduced to six molecular species and to three chemical reactions. With this basis and using estimated values of diffusion coefficients, the growth rates of epitaxial gallium arsenide layers have been a priori computed in dependence of the feed rate, its composition and on temperature. The predicted three dependences are discussed from the view-point of their courses and of the significance of computed results.

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.

Increased Growth Rate in a SiC CVD Reactor Using HCl as a Growth Additive

2005 ◽  
Vol 483-485 ◽  
pp. 73-76 ◽  
Author(s):  
Rachael L. Myers-Ward ◽  
Olof Kordina ◽  
Z. Shishkin ◽  
Shailaja P. Rao ◽  
R. Everly ◽  
...  
Keyword(s):  
Growth Rate ◽  
Epitaxial Growth ◽  
Gas Phase ◽  
Hydrogen Chloride ◽  
Growth Rates ◽  
Growth Process ◽  
Cluster Formation ◽  
Film Morphology ◽  
Hydrogen Carrier ◽  
Low Crystalline

Hydrogen chloride (HCl) was added to a standard SiC epitaxial growth process as an additive gas. A low-pressure, hot-wall CVD reactor, using silane and propane precursors and a hydrogen carrier gas, was used for these experiments. It is proposed that the addition of HCl suppresses Si cluster formation in the gas phase, and possibly also preferentially etches material of low crystalline quality. The exact mechanism of the growth using an HCl additive is still under investigation, however, higher growth rates could be obtained and the surfaces were improved when HCl was added to the flow. The film morphology was studied using SEM and AFM and the quality with LTPL analysis, which are reported.

Do gas phase adducts form during metalorganic vapour phase epitaxial growth of gallium arsenide?

1994 ◽  
Vol 145 (1-4) ◽  
pp. 104-112 ◽  
Author(s):  
Douglas F. Foster ◽  
Christopher Glidewell ◽  
David J. Cole-Hamilton ◽  
Ian M. Povey ◽  
Richard D. Hoare ◽  
...  
Keyword(s):  
Gallium Arsenide ◽  
Epitaxial Growth ◽  
Gas Phase ◽  
Vapour Phase

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.

Measurement of growth rates for single crystals and pressed tablets of CuSO4.5 H2O on a rotating disc

1989 ◽  
Vol 54 (11) ◽  
pp. 2951-2961 ◽  
Author(s):  
Miloslav Karel ◽  
Jaroslav Nývlt
Keyword(s):  
Growth Rate ◽  
Single Crystal ◽  
Single Crystals ◽  
Growth Rates ◽  
Diffusion Coefficients ◽  
Preferred Orientation ◽  
Rotating Disc ◽  
Dissolution Rates ◽  
Rates Of Growth ◽  
Good Agreement

Measured growth and dissolution rates of single crystals and tablets were used to calculate the overall linear rates of growth and dissolution of CuSO4.5 H2O crystals. The growth rate for the tablet is by 20% higher than that calculated for the single crystal. It has been concluded that this difference is due to a preferred orientation of crystal faces on the tablet surface. Calculated diffusion coefficients and thicknesses of the diffusion and hydrodynamic layers in the vicinity of the growing or dissolving crystal are in good agreement with published values.

An homogeneous growth model of gallium arsenide epitaxial layers from the gas phase

1989 ◽  
Vol 54 (11) ◽  
pp. 2933-2950
Author(s):  
Emerich Erdös ◽  
Petr Voňka ◽  
Josef Stejskal ◽  
Přemysl Klíma
Keyword(s):  
Experimental Data ◽  
Gallium Arsenide ◽  
Kinetic Study ◽  
Gas Phase ◽  
Growth Model ◽  
Epitaxial Layers ◽  
Inhomogeneous Model ◽  
Homogeneous Models ◽  
Active Centres

This paper represents a continuation and ending of the kinetic study of the gallium arsenide formation, where a so-called inhomogeneous model is proposed and quantitatively formulated in five variants, in which two kinds of active centres appear. This model is compared both with the experimental data and with the previous sequence of homogeneous models.

The effect of surfactants on epitaxial growth of gallium nitride from gas phase in the Ga-HCl-NH3-H2-Ar system

2015 ◽  
Vol 41 (5) ◽  
pp. 476-478 ◽  
Author(s):  
Yu. V. Zhilyaev ◽  
V. V. Zelenin ◽  
T. A. Orlova ◽  
V. N. Panteleev ◽  
N. K. Poletaev ◽  
...  
Keyword(s):  
Gallium Nitride ◽  
Epitaxial Growth ◽  
Gas Phase

On a reaction–diffusion system modelling infectious diseases without lifetime immunity

2021 ◽  
pp. 1-25
Author(s):  
HONG-MING YIN
Keyword(s):  
Diffusion Coefficients ◽  
A Priori ◽  
Main Tool ◽  
Reaction Diffusion ◽  
Reaction Diffusion System ◽  
Diffusion System ◽  
Sobolev Embedding ◽  
System Modelling ◽  
Strongly Coupled ◽  
Elliptic And Parabolic Equations

In this paper, we study a mathematical model for an infectious disease caused by a virus such as Cholera without lifetime immunity. Due to the different mobility for susceptible, infected human and recovered human hosts, the diffusion coefficients are assumed to be different. The resulting system is governed by a strongly coupled reaction–diffusion system with different diffusion coefficients. Global existence and uniqueness are established under certain assumptions on known data. Moreover, global asymptotic behaviour of the solution is obtained when some parameters satisfy certain conditions. These results extend the existing results in the literature. The main tool used in this paper comes from the delicate theory of elliptic and parabolic equations. Moreover, the energy method and Sobolev embedding are used in deriving a priori estimates. The analysis developed in this paper can be employed to study other epidemic models in biological, ecological and health sciences.

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