A Three-Dimensional Analysis of Particle Deposition for the Modified Chemical Vapor Deposition (MCVD) Process

1992 ◽  
Vol 114 (3) ◽  
pp. 735-742 ◽  
Author(s):  
Y. T. Lin ◽  
M. Choi ◽  
R. Greif
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Particle Deposition ◽  
Three Dimensional ◽  
Chemical Vapor ◽  
Secondary Flows ◽  
Circumferential Direction ◽  
Forced Flow ◽  
Flow Rates ◽  
Entry Length

A study has been made of the deposition of particles that occurs during the modified chemical vapor deposition (MCVD) process. The three-dimensional conservation equations of mass, momentum, and energy have been solved numerically for forced flow, including the effects of buoyancy and variable properties in a heated, rotating tube. The motion of the particles that are formed is determined from the combined effects resulting from thermophoresis and the forced and secondary flows. The effects of torch speed, rotational speed, inlet flow rate, tube radius, and maximum surface temperature on deposition are studied. In a horizontal tube, buoyancy results in circumferentially nonuniform temperature and velocity fields and particle deposition. The effect of tube rotation greatly reduces the nonuniformity of particle deposition in the circumferential direction. The process is chemical-reaction limited at larger flow rates and particle-transport limited at smaller flow rates. The vertical tube geometry has also been studied because its symmetric configuration results in uniform particle deposition in the circumferential direction. The “upward” flow condition results in a large overall deposition efficiency, but this is also accompanied by a large “tapered entry length.”

Analysis of Buoyancy and Tube Rotation Relative to the Modified Chemical Vapor Deposition Process

1990 ◽  
Vol 112 (4) ◽  
pp. 1063-1069 ◽  
Author(s):  
M. Choi ◽  
Y. T. Lin ◽  
R. Greif
Keyword(s):  
Secondary Flow ◽  
Vapor Deposition ◽  
Particle Deposition ◽  
Three Dimensional ◽  
Chemical Vapor ◽  
Horizontal Tube ◽  
Deposition Process ◽  
Secondary Flows ◽  
Secondary Motion

The secondary flows resulting from buoyancy effects in respect to the MCVD process have been studied in a rotating horizontal tube using a perturbation analysis. The three-dimensional secondary flow fields have been determined at several axial locations in a tube whose temperature varies in both the axial and circumferential directions for different rotational speeds. For small rotational speeds, buoyancy and axial convection are dominant and the secondary flow patterns are different in the regions near and far from the torch. For moderate rotational speeds, the effects of buoyancy, axial and angular convection are all important in the region far from the torch where there is a spiraling secondary flow. For large rotational speeds, only buoyancy and angular convection effects are important and no spiraling secondary motion occurs far downstream. Compared with thermophoresis, the important role of buoyancy in determining particle trajectories in MCVD is presented. As the rotational speed increases, the importance of the secondary flow decreases and the thermophoretic contribution becomes more important. It is noted that thermophoresis is considered to be the main cause of particle deposition in the MCVD process.

scholarly journals Role of Arsenic Hexagonal growth-suppression on a Cubic GaNAs Growth using Metalorganic Chemical Vapor Deposition

2000 ◽  
Vol 5 (S1) ◽  
pp. 223-229 ◽  
Author(s):  
S. Yoshida ◽  
T. Kimura ◽  
J. Wu ◽  
J. Kikawa ◽  
K. Onabe ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Flow Rate ◽  
Vapor Deposition ◽  
Metalorganic Chemical Vapor Deposition ◽  
Three Dimensional ◽  
Chemical Vapor ◽  
Photoluminescence Intensity ◽  
Flow Rates ◽  
Surface Morphologies ◽  
Metalorganic Chemical

The hexagonal domain suppression-effects in cubic-GaNAs grown by metalorganic chemical-vapor deposition (MOCVD) is reported. A thin buffer layer (20 nm) was first grown on a substrate at 853 K using trimethylgallium and dimethylhydrazine (DMHy), and GaNAs samples were grown at different AsH3 flow rates (0 ∼ 450 μmol/min) at 1193 K. As a result, three types of surface morphologies were obtained: the first was a smooth surface (AsH3 = 0 μmol/min); the second was a mirrorlike surface having small and isotropic grains (AsH3 : 45 ∼ 225 μmol/min ); and the third involved three-dimensional surface morphologies (above 450 μmol/min of AsH3 flow rate). Furthermore, it was confirmed using X-ray diffraction that the mixing ratio of hexagonal GaNAs in cubic GaNAs decreased with an increase of the AsH3 flow rate. We could obtain GaNAs having a cubic component of above 85% at AsH3 flow rates above 20 μmol/min. Therefore, the MOCVD growth method using AsH3 and DMHy was mostly effective for suppressing hexagonal GaNAs. It was observed that the photoluminescence intensity of GaNAs was decreased with increase of arsine flow rate.

A Three-Dimensional Analysis of the Flow and Heat Transfer for the Modified Chemical Vapor Deposition Process Including Buoyancy, Variable Properties, and Tube Rotation

1991 ◽  
Vol 113 (2) ◽  
pp. 400-406 ◽  
Author(s):  
Y. T. Lin ◽  
M. Choi ◽  
R. Greif
Keyword(s):  
Heat Transfer ◽  
Chemical Vapor Deposition ◽  
Secondary Flow ◽  
Vapor Deposition ◽  
Axial Velocity ◽  
Particle Deposition ◽  
Three Dimensional ◽  
Chemical Vapor ◽  
Deposition Process ◽  
Variable Properties

A study has been made of the heat transfer, flow, and particle deposition relative to the modified chemical vapor deposition (MCVD) process. The effects of variable properties, buoyancy, and tube rotation have been included in the study. The resulting three-dimensional temperature and velocity fields have been obtained for a range of conditions. The effects of buoyancy result in asymmetric temperature and axial velocity profiles with respect to the tube axis. Variable properties cause significant variations in the axial velocity along the tube and in the secondary flow in the region near the torch. Particle trajectories are shown to be strongly dependent on the tube rotation and are helices for large rotational speeds. The component of secondary flow in the radial direction is compared to the thermophoretic velocity, which is the primary cause of particle deposition in the MCVD process. Over the central portion of the tube the radial component of the secondary flow is most important in determining the motion of the particles.

Heteroepitaxial Nucleation and Growth of Ge ON Si(100) Surfaces Using Remote Plasma Enhanced Chemical Vapor Deposition

1988 ◽  
Vol 116 ◽  
Author(s):  
R.A. Rudder ◽  
S.V. Hattangady ◽  
D.J. Vitkavage ◽  
R.J. Markunas
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Photoelectron Spectroscopy ◽  
Three Dimensional ◽  
Chemical Vapor ◽  
Layer By Layer ◽  
Heteroepitaxial Growth ◽  
Remote Plasma ◽  
Dimensional Growth ◽  
Diffraction Patterns

Heteroepitaxial growth of Ge on Si(100) has been accomplished using remote plasma enhanced chemical vapor deposition at 300*#x00B0;C. Reconstructed surfaces with diffraction patterns showing non-uniform intensity variations along the lengths of the integral order streaks are observed during the first 100 Å of deposit. This observation of an atomically rough surface during the initial stages of growth is an indication of three-dimensional growth. As the epitaxial growth proceeds, the diffraction patterns become uniform with extensive streaking on both the integral and fractional order streaks. Subsequent growth, therefore, takes place in a layer-by-layer, two-dimensional mode. X-ray photoelectron spectroscopy of the early nucleation stages, less than 80 Å, show that there is uniform coverage with no evidence of island formation.

The Effects of Hydrogen Flowrate during Pre-Annealing on Graphene Growth by Chemical Vapor Deposition Using Methanol as a Liquid Carbon Precursor

2019 ◽  
Vol 290 ◽  
pp. 107-112
Author(s):  
Raed Abdalrheem ◽  
Fong Kwong Yam ◽  
Abdul Razak Ibrahim ◽  
Khi Poay Beh ◽  
Hwee San Lim ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Light Transmittance ◽  
High Hydrogen ◽  
Flow Rates ◽  
Hydrogen Flow ◽  
Number Of Layers ◽  
Crystallite Sizes ◽  
Grown Graphene

Studying an influence of several parameters on Chemical Vapor Deposition (CVD) used for graphene synthesis is crucial to optimizing the graphene quality to be Compatible with advanced devices. The effect of different hydrogen (H2) flow-rates (0, 50, 100, 150, 200, 250, and 300 sccm) during the pre-annealing process on CVD grown graphene have been reported. This study revealed that hydrogen flow rates during annealing changed the surface roughness/smoothness of the copper substrates. For high hydrogen flow rates, the smoothing effect was increased. Furthermore, the annealed graphene samples emerged a deferent number of layers because of morphological surface changes. According to Raman D- to G-band intensity ratios (ID/IG), the graphene quality was influenced by the annealing hydrogen flowrate. The visible light transmittance values of the grown graphene samples confirmed a few number of layers (mono to seven-layer). Mostly, the samples which annealed under moderate hydrogen flow rates showed less defects intensities and higher crystallite sizes.

Synthesis of three-dimensional graphene from petroleum asphalt by chemical vapor deposition

2014 ◽  
Vol 122 ◽  
pp. 285-288 ◽  
Author(s):  
Zhuchen Liu ◽  
Zhiqiang Tu ◽  
Yongfeng Li ◽  
Fan Yang ◽  
Shuang Han ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Three Dimensional ◽  
Chemical Vapor ◽  
Petroleum Asphalt

Synthesis of Graphene-ZnO Heterogeneous Nanostructures by Chemical Vapor Deposition

2011 ◽  
Vol 1348 ◽  
Author(s):  
Jian Lin ◽  
Miroslav Penchev ◽  
Guoping Wang ◽  
Rajat K Paul ◽  
Jiebin Zhong ◽  
...  
Keyword(s):  
Optical Properties ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Three Dimensional ◽  
Chemical Vapor ◽  
Building Blocks ◽  
Zno Nanostructures ◽  
Large Area ◽  
Graphene Layers

ABSTRACTIn this work, we report the synthesis and characterization of three dimensional heterostructures graphene nanostructures (HGN) comprising continuous large area graphene layers and ZnO nanostructures, fabricated via chemical vapor deposition. Characterization of large area HGN demonstrates that it consists of 1-5 layers of graphene, and exhibits high optical transmittance and enhanced electrical conductivity. Electron microscopy investigation of the three dimensional heterostructures shows that the morphology of ZnO nanostructures is highly dependent on the growth temperature. It is observed that ordered crystalline ZnO nanostructures are preferably grown along the <0001> direction. Ultraviolet spectroscopy indicates that the CVD grown HGN layers has excellent optical properties. A combination of electrical and optical properties of graphene and ZnO building blocks in ZnO based HGN provides unique characteristics for opportunities in future optoelectronic devices.

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