Regularities of Fluoropolymer Coating Growth on Pretreated Surfaces from Active Gas Phase

2019 ◽  
Vol 970 ◽  
pp. 55-62
Author(s):  
Alexander A. Rogachev ◽  
Petr A. Luchnikov ◽  
Oleg A. Sarkisov ◽  
Alexander V. Rogachev ◽  
Inna Plotnikova
Keyword(s):  
Growth Rate ◽  
Surface Energy ◽  
Gas Phase ◽  
Substrate Surface ◽  
Surface Activation ◽  
Physicomathematical Model ◽  
Apparent Thickness ◽  
Initial Stage ◽  
Fluoropolymer Coating ◽  
Coating Growth

The kinetic and morphological peculiarities of polytetrafluoroethylene (PTFE) coating growth onset from the active gas phase on differently pretreated substrates are considered. The substrate surface energy was found to exert an effect on distribution of polymer micro-and nanoparticles both at the initial stage so during coating growth. The substrate surface activation was proved to result in the increasing growth rate and formation of a continuous coating with a thinner apparent thickness. The physicomathematical model of presented regularities was elaborated.

Diffusion model for deposition of epitaxial GaAs layers prepared by the MOCVD method

1991 ◽  
Vol 56 (10) ◽  
pp. 2020-2029
Author(s):  
Jindřich Leitner ◽  
Petr Voňka ◽  
Josef Stejskal ◽  
Přemysl Klíma ◽  
Rudolf Hladina
Keyword(s):  
Experimental Data ◽  
Growth Rate ◽  
Kinetic Model ◽  
Gas Phase ◽  
Substrate Surface ◽  
Deposition Process ◽  
Hydrogen Atmosphere ◽  
Epitaxial Gaas ◽  
Kinetics Of ◽  
Good Agreement

The authors proposed and treated quantitatively a kinetic model for deposition of epitaxial GaAs layers prepared by reaction of trimethylgallium with arsine in hydrogen atmosphere. The transport of gallium to the surface of the substrate is considered as the controlling process. The influence of the rate of chemical reactions in the gas phase and on the substrate surface on the kinetics of the deposition process is neglected. The calculated dependence of the growth rate of the layers on the conditions of the deposition is in a good agreement with experimental data in the temperature range from 600 to 800°C.

Diamond growth with locally supplied methane and acetylene

1992 ◽  
Vol 7 (2) ◽  
pp. 379-383 ◽  
Author(s):  
W.A. Yarbrough ◽  
K. Tankala ◽  
T. DebRoy
Keyword(s):  
Growth Rate ◽  
Gas Phase ◽  
Substrate Surface ◽  
Hydrogen Abstraction ◽  
Diamond Growth ◽  
Methyl Radical ◽  
Vapor Phase Deposition ◽  
Major Species ◽  
Deposition Uniformity ◽  
Hot Filament

Experiments have been conducted to examine the relative importance of different gas feed geometries and molecular species in the hot filament assisted vapor phase deposition of diamond. Remote and local (relative to the substrate) gas feeds of methane and acetylene were tested and it was found that although dramatic effects on uniformity and rate of deposition can be observed using a gas feed of methane local to the substrate surface, little or no variation in growth rate or deposition uniformity was produced by feeding acetylene locally. The growth rate observed on a defined area of the substrate using a local gas feed of methane was 0.50 mgms/h versus 0.17 mgms/h for a local feed of acetylene. These results, as well as the patterns of deposition observed, suggest that the major species contributing to growth in the hot filament assisted CVD of diamond is the methyl radical. This species is readily formed in the gas phase from methane and atomic hydrogen by hydrogen abstraction. It is, however, further suggested that numerous different hydrocarbon species may be of importance, with the nature of the species contributing most to the growth dependent on the method used.

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.

Direct Nucleation of Crystalline SiGe on Substrates by Reactive Thermal CVD with Si2H6 and GeF4

1997 ◽  
Vol 467 ◽  
Author(s):  
Fumio Yoshizawa ◽  
Kunihiro Shiota ◽  
Daisuke Inoue ◽  
Jun-ichi Hanna
Keyword(s):  
Growth Rate ◽  
Gas Phase ◽  
Heterogeneous Nucleation ◽  
Homogeneous Nucleation ◽  
Film Growth ◽  
Early Stage ◽  
Gaseous Mixture ◽  
The Other ◽  
Thermal Cvd ◽  
Initial Deposition

ABSTRACTPolycrystalline SiGe (poly-SiGe) film growth by reactive thermal CVD with a gaseous mixture of Si2H6 and GeF4 was investigated on various substrates such as Al,Cr, Pt, Si, ITO, ZnO and thermally grown SiO2.In Ge-rich film growth, SEM observation in the early stage of the film growth revealed that direct nucleation of crystallites took place on the substrates. The nucleation was governed by two different mechanisms: one was a heterogeneous nucleation on the surface and the other was a homogeneous nucleation in the gas phase. In the former case, the selective nucleation was observed at temperatures lower than 400°C on metal substrates and Si, where the activation of adsorbed GeF4 on the surface played a major role for the nuclei formation, leading to the selective film growth.On the other hand, the direct nucleation did not always take place in Si-rich film growth irrespective of the substrates and depended on the growth rate. In a growth rate of 3.6nm/min, the high crystallinity of poly-Si0.95Ge0.05in a 220nm-thick film was achieved at 450°C due to the no initial deposition of amorphous tissue on SiO2 substrates.

Computer simulations of interactions between ultrafine alumina particles produced by an arc discharge

1997 ◽  
Vol 12 (1) ◽  
pp. 235-243 ◽  
Author(s):  
M. H. Teng ◽  
L. D. Marks ◽  
D. L. Johnson
Keyword(s):  
Electron Microscope ◽  
Surface Energy ◽  
Transmission Electron Microscope ◽  
Arc Discharge ◽  
Total Surface Energy ◽  
Transmission Electron ◽  
Initial Stage ◽  
Alumina Particles ◽  
Rearrangement Process ◽  
Particle Chains

We wrote two computer programs, 3D and BUMP, to interpret transmission electron microscope (TEM) micrographs made during a study of the initial stage sintering of ultrafine alumina particles (UFP's, 20–50 nm in diameter). The first simulated the 3D geometric relationships of particles, from which we concluded that surface diffusion was the predominant sintering mechanism because no shrinkage occurred. BUMP simulated random contact of two particles and showed that the particle chains that formed before sintering were not formed purely by chance. Instead the particles experienced a rearrangement process (rotation and sliding) which reduced the total surface energy.

scholarly journals Growth of GaN from elemental Gallium and Ammonia via Modified Sandwich Growth Technique

2004 ◽  
Vol 831 ◽  
Author(s):  
E. Berkman ◽  
R. Collazo ◽  
R. Schlesser ◽  
Z. Sitar
Keyword(s):  
Growth Rate ◽  
Gas Flow ◽  
Transport Model ◽  
Theoretical Calculations ◽  
Substrate Surface ◽  
Maximum Growth ◽  
Direct Reaction ◽  
Pure Nitrogen ◽  
Flow Rates ◽  
Reactor Pressure

ABSTRACTGallium nitride (GaN) films were grown on (0001) sapphire substrates at 1050°C by controlled evaporation of gallium (Ga) metal and reaction with ammonia (NH3) at a total reactor pressure of 800 Torr. Pure nitrogen (N2) was flowed directly above the molten Ga source to prevented direct reaction between the molten Ga and ammonia, which causes Ga spattering and GaN crust formation. At the same time, this substantially enhanced the Ga transport to the substrate. A simple mass-transport model based on total reactor pressure, gas flow rates and source temperature was developed and verified. The theoretical calculations and growth rate measurements at different ammonia flow rates and reactor pressures showed that the maximum growth rate was controlled by transport of both Ga species and reactive ammonia to the substrate surface.

Prospects for Cooperation Between Russia and Syria in Various Scenarios of Military Conflict Development

2021 ◽  
pp. 50-55
Author(s):  
Alheder Haled
Keyword(s):  
Growth Rate ◽  
Inverse Correlation ◽  
Foreign Economic Policy ◽  
Military Conflict ◽  
Political Situation ◽  
Gdp Growth Rate ◽  
Initial Stage ◽  
Military Conflicts ◽  
The Military ◽  
The Relationship

The paper is devoted to determining the prospects for cooperation between Russia and the Syrian Arab Republic in various scenarios of military conflicts. In order to identify the relationship between the success of the country's foreign economic policy and the military conflicts waged on its territory, a study was conducted of such indicators of Syria as: the growth rate of the peace index and the GDP growth rate. A strong inverse correlation is revealed, which means that the level of political situation and peace in the state determines the efficiency of the economy. In view of this, various scenarios of the development of the military conflict in Syria have been studied: at the initial stage, at the stage of active hostilities, at the present stage of overcoming the crisis. The last stage involves four different scenarios for the development of a military conflict, including a local nature and a protracted nature with the involvement of other countries of the world. Options for developing cooperation between Russia and Syria have been identified for each scenario. Taking into account the assessment of the international political situation, the two most likely scenarios for further military events in Syria are identified, and the prospects for cooperation between Russia and Syria in these conditions are outlined.

Substrate Dependence of Microcrystalline Silicon Growth with SiH4 Diluted by Ar

2014 ◽  
Vol 936 ◽  
pp. 264-268
Author(s):  
Hua Cheng ◽  
Yong Chan Qian ◽  
Jun Xue
Keyword(s):  
Deposition Rate ◽  
Electron Cyclotron Resonance ◽  
Substrate Surface ◽  
Gaseous Mixture ◽  
Film Surface ◽  
Chemical Vapor ◽  
Preferred Orientation ◽  
Initial Stage ◽  
Substrate Dependence ◽  
Si Films

Microcrystalline Si films were deposited by electron cyclotron resonance plasma-enhanced chemical vapor deposition (ECR-PECVD) using Ar diluted SiH4gaseous mixture. The effects of the substrate on deposition rate, preferred orientation and roughness of the films were investigated. The results show that, the influence of the substrate surface chemical nature on the deposition rate is significant in the initial stage of the growth. And considering the crystallinity and roughness of the films, the substrate is favored in its preferred orientation with a rougher surface. Based on these results, it is confirmed that the combination of diffusion and etching is indispensable to describe the deposition of μc-Si with SiH4diluted by Ar, and the mechanism of μc-Si growth could be controlled by diffusion of Si and etching of the Ar+on the film surface.

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