Computational Experiment on CVD of SiC: Growth Rate, C/Si Ratio, Parasitic Phase Formation

2000 ◽  
Vol 616 ◽  
Author(s):  
Andrei N. Vorob'ev ◽  
Alexandre E. Komissarov ◽  
Maxim V. Bogdanov ◽  
Sergey Yu. Karpov ◽  
Olga V. Bord ◽  
...  
Keyword(s):  
Growth Rate ◽  
Phase Formation ◽  
Homogeneous Nucleation ◽  
Transport Model ◽  
Cluster Formation ◽  
Secondary Phase ◽  
Silicon Cluster ◽  
Rotating Disc ◽  
Flow Rates ◽  
Wide Range

AbstractThe heat and mass transport model extended to describe silicon cluster formation in the gas phase is employed for a numerical analysis of SiC CVD in a commercial vertical rotating disc reactor. The growth rate is studied as a function of precursor flow rates varied in a wide range of values. It is found that the growth rate is limited by the gas mixture depletion in silicon atoms due to homogeneous nucleation. The secondary phase formation on the growing surface is analyzed. The SiC growth window depending on the precursor flow rates is calculated, and a significant effect of the homogeneous nucleation on the window width is found. The model predicts that the Si/C ratio on the wafer can considerably differ from that at the reactor inlet.

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.

Kinetic Analysis on Nanoparticle Condensation by Molecular Dynamics

2013 ◽  
Vol 135 (10) ◽  
Author(s):  
Donguk Suh ◽  
Kenji Yasuoka
Keyword(s):  
Molecular Dynamics ◽  
Growth Rate ◽  
Free Energy ◽  
Kinetic Analysis ◽  
Seed Size ◽  
Homogeneous Nucleation ◽  
Cluster Formation ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Seed Particle

Condensation on a cubic seed particle was simulated by classical molecular dynamics (MD). Seed size and supersaturation ratio of the system were the factors that were examined in order to observe the effects of the dimension of seeds and thermodynamic conditions. Two stages of nucleation were observed in the phenomenon, where the first stage is from the seed growth and the second from homogeneous nucleation. Therefore, the nucleation rate and growth rate were each calculated by the Yasuoka–Matsumoto (YM) method. As the seed size increased, the growth rate decreased, but there was no clear seed influence on the homogeneous nucleation characteristics. Besides, the classical nucleation theory (CNT), cluster formation free energy and kinetic analysis were conducted. The free energy in the exponential term of the classical nucleation theory and that obtained from the cluster formation free energy showed different characteristics.

Kinetic Analysis on Nanoparticle Condensation by Molecular Dynamics

2012 ◽  
Author(s):  
Donguk Suh ◽  
Kenji Yasuoka
Keyword(s):  
Molecular Dynamics ◽  
Growth Rate ◽  
Free Energy ◽  
Kinetic Analysis ◽  
Seed Size ◽  
Homogeneous Nucleation ◽  
Cluster Formation ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Seed Particle

Condensation on a cubic seed particle was simulated by classical molecular dynamics. Seed size and supersaturation ratio of the system were the factors that were examined in order to observe the effects of the dimension of seeds and thermodynamic conditions. Two stages of nucleation were observed in the phenomenon, where the first stage is from the seed growth and the second from homogeneous nucleation. Therefore, the nucleation rate and growth rate were each calculated by the Yasuoka-Matsumoto method. As seed size increased the growth rate decreased, but there was no clear seed influence on the homogeneous nucleation characteristics. Besides the classical nucleation theory, cluster formation free energy and kinetic analysis were conducted. The free energy in the exponential term of the classical nucleation theory and that obtained from the cluster formation free energy showed different characteristics.

scholarly journals Heat Transfer in a Rotating Cavity With a Stationary Stepped Casing

1998 ◽  
Author(s):  
Iraj Mirzaee ◽  
Paul Quinn ◽  
Michael Wilson ◽  
J. Michael Owen
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Flow Parameter ◽  
Rotating Disc ◽  
Flow Rates ◽  
Nusselt Numbers ◽  
Rotating Cavity ◽  
Wide Range ◽  
Heated Disc ◽  
Cooling Air

In the system considered here, corotating “turbine” discs are cooled by air supplied at the periphery of the system. The system comprises two corotating discs, connected by a rotating cylindrical hub and shrouded by a stepped, stationary cylindrical outer casing. Cooling air enters the system through holes in the periphery of one disc, and leaves through the clearances between the outer casing and the discs. The paper describes a combined computational and experimental study of the heat transfer in the above system. In the experiments, one rotating disc is heated, the hub and outer casing are insulated, and the other disc is quasi-adiabatic. Thermocouples and fluxmeters attached to the heated disc enable the Nusselt numbers, Nu, to be determined for a wide range of rotational speeds and coolant flow rates. Computations are carried out using an axisymmetric elliptic solver incorporating the Launder-Sharma low-Reynolds-number k-ε turbulence model. The flow structure is shown to be complex and depends strongly on the so-called turbulent flow parameter, λT, which incorporates both rotational speed and flow rate. For a given value of λT, the computations show that Nu increases as Reϕ, the rotational Reynolds number, increases. Despite the complexity of the flow, the agreement between the computed and measured Nusselt numbers is reasonably good.

Convection Effects in Epitaxial Reactors: an Experimental and Theoretical Study

1988 ◽  
Vol 144 ◽  
Author(s):  
P. B. Chinoy ◽  
P. D. Agnello ◽  
S. K. Ghandhia
Keyword(s):  
Mathematical Model ◽  
Growth Rate ◽  
Energy Transfer ◽  
Natural Convection ◽  
Gas Flow ◽  
Theoretical Study ◽  
Excellent Correlation ◽  
Flow Rates ◽  
Wide Range ◽  
Experimental Vehicle

ABSTRACTAn experimental and theoretical study has been undertaken of the effects of natural and forced convection in horizontal epitaxial reactors. The epitaxial growth of GaAs was used as the experimental vehicle for this study. A mathematical model for mass, momentum and energy transfer in the reactor was developed. Excellent correlation between modeled and experimental results was demonstrated over a wide range of reactor pressures and susceptor geometries. Recirculation of hot gases, caused by natural convection, was found to result in a strong pressure dependence of growth rate at higher susceptor slopes. Low reactor pressures have been shown to be a more effective way to eliminate recirculation than high gas flow rates.

Automation of Process Control in Chemical Plant

2015 ◽  
Vol 2 (1) ◽  
pp. 6-12
Author(s):  
Agus Sugiarta ◽  
Houtman P. Siregar ◽  
Dedy Loebis
Keyword(s):  
Process Control ◽  
Pid Control ◽  
Control Algorithm ◽  
Chemical Engineering ◽  
Chemical Plant ◽  
Raw Material ◽  
Flow Rates ◽  
Material Supply ◽  
Wide Range ◽  
Inherent Problem

Automation of process control in chemical plant is an inspiring application field of mechatronicengineering. In order to understand the complexity of the automation and its application requireknowledges of chemical engineering, mechatronic and other numerous interconnected studies.The background of this paper is an inherent problem of overheating due to lack of level controlsystem. The objective of this research is to control the dynamic process of desired level more tightlywhich is able to stabilize raw material supply into the chemical plant system.The chemical plant is operated within a wide range of feed compositions and flow rates whichmake the process control become difficult. This research uses modelling for efficiency reason andanalyzes the model by PID control algorithm along with its simulations by using Matlab.

Nitrogen Removal from Anaerobically-Treated Leachate

1984 ◽  
Vol 19 (1) ◽  
pp. 87-100
Author(s):  
D. Prasad ◽  
J.G. Henry ◽  
P. Elefsiniotis
Keyword(s):  
Nitrogen Removal ◽  
Air Flow ◽  
Operating Conditions ◽  
Air Flow Rate ◽  
Flow Rates ◽  
Anaerobic Filter ◽  
Ph Values ◽  
Wide Range ◽  
Ammonia Desorption ◽  
Effects Of Ph

Abstract Laboratory studies were conducted to demonstrate the effectiveness of diffused aeration for the removal of ammonia from the effluent of an anaerobic filter treating leachate. The effects of pH, temperature and air flow on the process were studied. The coefficient of desorption of ammonia, KD for the anaerobic filter effluent (TKN 75 mg/L with NH3-N 88%) was determined at pH values of 9, 10 and 11, temperatures of 10, 15, 20, 30 and 35°C, and air flow rates of 50, 120, and 190 cm3/sec/L. Results indicated that nitrogen removal from the effluent of anaerobic filters by ammonia desorption was feasible. Removals exceeding 90% were obtained with 8 hours aeration at pH of 10, a temperature of 20°C, and an air flow rate of 190 cm3/sec/L. Ammonia desorption coefficients, KD, determined at other temperatures and air flow rates can be used to predict ammonia removals under a wide range of operating conditions.

Comparison of copper sulphate pentahydrate growth rates determined by different methods

1990 ◽  
Vol 55 (7) ◽  
pp. 1691-1707 ◽  
Author(s):  
Miloslav Karel ◽  
Jiří Hostomský ◽  
Jaroslav Nývlt ◽  
Axel König
Keyword(s):  
Growth Rate ◽  
Crystal Growth ◽  
Fluidized Bed ◽  
Growth Rates ◽  
Copper Sulphate ◽  
Crystal Growth Rate ◽  
Effect Of Temperature ◽  
Rotating Disc ◽  
Shape Factors ◽  
Data Treatment

Crystal growth rates of copper sulphate pentahydrate (CuSO4.5 H2O) determined by different authors and methods are compared. The methods included in this comparison are: (i) Measurement on a fixed crystal suspended in a streaming solution, (ii) measurement on a rotating disc, (iii) measurement in a fluidized bed, (iv) measurement in an agitated suspension. The comparison involves critical estimation of the supersaturation used in measurements, of shape factors used for data treatment and a correction for the effect of temperature. Conclusions are drawn for the choice of values to be specified when data of crystal growth rate measurements are published.

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.

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