Effect of Solution Drift on Crystalline Morphology in the Solution Growth of Off-Axis 4H-SiC Crystals

2016 ◽  
Vol 858 ◽  
pp. 65-68
Author(s):  
Takashi Kato ◽  
Kazuhiko Kusunoki ◽  
Kazuaki Seki ◽  
Nobuhiro Okada ◽  
Kazuhito Kamei
Keyword(s):  
Surface Morphology ◽  
Flow Direction ◽  
Solute Concentration ◽  
The Other ◽  
Solution Growth ◽  
Morphological Stability ◽  
Crystalline Morphology ◽  
Solution Flow ◽  
Step Flow ◽  
Flow Directions

We investigated the effect of the solution flow on crystalline morphology in the off-axis 4H-SiC solution growth. In particular, we focused on the relation between the Si solution flow and step flow directions. In step parallel flow in which the solution drifted transversely to the step flow direction of the off-axis substrate, it was possible to attain a better surface morphology than in the flow in which the solution drifted toward the other direction. Furthermore, it was found that the surface morphology was found to be improved as the solution flow velocity increased. These improvements in the morphological stability are presumed to be caused by aligning the solute concentration fluctuation along the steps.

Improvement of Surface Morphology by Solution Flow Control in Solution Growth of SiC on Off-Axis Seeds

2015 ◽  
Vol 821-823 ◽  
pp. 31-34 ◽  
Author(s):  
Tomonori Umezaki ◽  
Daiki Koike ◽  
S. Harada ◽  
Toru Ujihara
Keyword(s):  
Flow Direction ◽  
Seed Crystal ◽  
Solution Growth ◽  
Rotational Axis ◽  
Solution Flow ◽  
Step Flow ◽  
Unidirectional Flow ◽  
Novel Method ◽  
Set Up ◽  
Top Seeded Solution Growth

The solution growth of SiC on an off-axis seed is effective on the reduction of threading dislocations. We proposed a novel method to grow a SiC crystal on an off-axis seed by top-seeded solution growth (TSSG). In our previous study, a unidirectional solution flow above a seed crystal is effective to suppress surface roughness in the growth on the off-axis seed. However, it is difficult to apply the unidirectional flow in an axisymmetric TSSG set-up. In this study, the unidirectional flow could be achieved by shifting the rotational axis away from the center of the seed crystal. As a result, the smooth surface was obtained in the wider area where the solution flow direction was opposite to the step-flow direction.

Formation of Basal Plane Dislocations Introduced by Collision of Macrosteps on Growth Surface during SiC Solution Growth

2017 ◽  
Vol 897 ◽  
pp. 28-31
Author(s):  
Tsukasa Hori ◽  
Kenta Murayama ◽  
S. Harada ◽  
S. Xiao ◽  
M. Tagawa ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Surface Morphology ◽  
Basal Plane ◽  
The Other ◽  
Solution Growth ◽  
Interference Microscopy ◽  
Growth Surface ◽  
X Ray ◽  
Top Seeded Solution Growth ◽  
The Relationship

The relationship between surface morphology and spatial distribution of basal plane dislocations in 4H-SiC crystal grown by top-seeded solution growth on the C face was investigated by the differential interference microscopy as well as X-ray topography. Basal plane dislocations were generated at the boundaries of the domains with the different macrosteps advance directions. On the other hand, at the position where macrosteps advance to the same direction, BPDs were hardly observed. This results suggest that BPD density can be decreased by the suppression of the collision of macrosteps during the solution growth on the C face controlling the surface morphology.

Surface Morphology and Threading Dislocation Conversion Behavior during Solution Growth of 4H-SiC Using Al-Si Solvent

2014 ◽  
Vol 778-780 ◽  
pp. 67-70 ◽  
Author(s):  
S. Harada ◽  
Yuji Yamamoto ◽  
S. Xiao ◽  
M. Tagawa ◽  
Toru Ujihara
Keyword(s):  
Surface Morphology ◽  
Screw Dislocation ◽  
Edge Dislocation ◽  
Grown Crystal ◽  
The Other ◽  
Solution Growth ◽  
Growth Surface ◽  
Threading Dislocation ◽  
Other Hand

Surface morphology and threading dislocation conversion behavior during solution growth of 4H-SiC using pure Si and Al-Si solvents was investigated. The growth surfaces on the C face were smoother than the Si face. By the addition of Al to the solvent, the growth surface became smooth on the C face and rough on the Si face. Threading screw dislocation conversion took place only in the grown crystals on the Si face and threading edge dislocation conversion occurs both on the Si face and the C face using the pure Si solvent. On the other hand, in the grown crystal on the C face using the Al-Si solvent, the threading dislocation conversion was hardly observed. These results indicate that the threading dislocation conversion behavior is influenced by the surface morphology.

Influences of Solution Flow and Lateral Temperature Distribution on Surface Morphology in Solution Growth of SiC

2015 ◽  
Vol 821-823 ◽  
pp. 35-38
Author(s):  
Kuniharu Fujii ◽  
Koichi Takei ◽  
Masahiro Aoshima ◽  
Nachimuthu Senguttuvan ◽  
Masahiko Hiratani ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Temperature Gradient ◽  
Surface Morphology ◽  
Rotation Rate ◽  
Flat Surface ◽  
Growth Front ◽  
Solution Growth ◽  
Solution Flow ◽  
Graphite Rod ◽  
Lateral Temperature

The influences of solution flow and lateral temperature distribution on the surface morphology of the 4H-SiC single crystal grown from solution was investigated. A flat surface region was enlarged by the seed-rotation rate. The solution flow simulation indicated that the higher rotation rate made the outward solution flow ordered beneath the solution surface. Such a solution flow was thought to be effective to enlarge the flat region of growth front. Furthermore, a full-flat surface was obtained with a hollow-type graphite rod at a seed-rotation rate of 60 min-1. The simulated results of temperature distribution showed the hollow-type graphite rod reduced the lateral temperature gradient at the SiC-solution interface. The ordered solution flow and the small temperature gradient at the growth front were found to be effective to make the growth front flat in the solution-growth method.

Control of Interface Shape by Non-Axisymmetric Solution Convection in Top-Seeded Solution Growth of SiC Crystal

2015 ◽  
Vol 821-823 ◽  
pp. 18-21 ◽  
Author(s):  
Daiki Koike ◽  
Tomonori Umezaki ◽  
Kenta Murayama ◽  
Kenta Aoyagi ◽  
S. Harada ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Flow Direction ◽  
Solution Growth ◽  
Interface Shape ◽  
Solution Flow ◽  
Growth Interface ◽  
Axisymmetric Solution ◽  
3 Dimensional ◽  
Unidirectional Flow ◽  
Top Seeded Solution Growth

We achieved the convex growth interface shape in top-seeded solution growth of SiC applying non-axisymmetric solution convection induced by non-axisymmetric temperature distribution. The detailed solution flow, temperature distribution and carbon concentration distribution were calculated by 3-dimensional numerical analysis. In the present case, the solution flow below the crystal was unidirectional and the supersaturation was increased along the solution flow direction. By the rotation of the crystal in the unidirectional flow and the temperature distribution, we successfully obtained the crystal with the convex growth interface shape.

Spatial Variability of Physical Parameters and Processes in Two Field Soils

1991 ◽  
Vol 22 (5) ◽  
pp. 327-340 ◽  
Author(s):  
K. Høgh Jensen ◽  
J. C. Refsgaard
Keyword(s):  
Transport Model ◽  
Flow Direction ◽  
Measurement Data ◽  
Flow Simulation ◽  
Solute Concentration ◽  
Conclusive Evidence ◽  
Physical Parameters ◽  
Effective Parameters ◽  
The Mean ◽  
Tracer Experiments

A numerical analysis of solute transport in two spatially heterogeneous fields is carried out assuming that the fields are composed of ensembles of one-dimensional non-interacting soil columns, each column representing a possible soil profile in statistical terms. The basis for the analysis is the flow simulation described in Part II (Jensen and Refsgaard, this issue), which serves as input to a transport model based on the convection-dispersion equation. The simulations of the average and variation in solute concentration in planes perpendicular to the flow direction are compared to measurements obtained from tracer experiments carried out at the two fields. Due to the limited amount of measurement data, it is difficult to draw conclusive evidence of the simulations, but reliable simulations are obtained of the mean behaviour within the two fields. The concept of equivalent soil properties is also tested for the transport problem in heterogeneous soils. Based on effective parameters for the retention and hydraulic conductivity functions it is possible to predict the mean transport in the two experimental fields.

Pressure Drop Measurements for Air Flow Through Open-Cell Aluminum Foam

2004 ◽  
Author(s):  
Nihad Dukhan ◽  
Angel Alvarez
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Flow Rate ◽  
Aluminum Foam ◽  
Flow Direction ◽  
The Other ◽  
Turbulent Regime ◽  
Thick Sample ◽  
Open Cell ◽  
Two Samples

Wind-tunnel pressure drop measurements for airflow through two samples of forty-pore-per-inch commercially available open-cell aluminum foam were undertaken. Each sample’s cross-sectional area perpendicular to the flow direction measured 10.16 cm by 24.13 cm. The thickness in the flow direction was 10.16 cm for one sample and 5.08 cm for the other. The flow rate ranged from 0.016 to 0.101 m3/s for the thick sample and from 0.025 to 0.134 m3/s for the other. The data were all in the fully turbulent regime. The pressure drop for both samples increased with increasing flow rate and followed a quadratic behavior. The permeability and the inertia coefficient showed some scatter with average values of 4.6 × 10−8 m2 and 2.9 × 10−8 m2, and 0.086 and 0.066 for the thick and the thin samples, respectively. The friction factor decayed with the Reynolds number and was weakly dependent on the Reynolds number for Reynolds number greater than 35.

scholarly journals Mixing of Particles in Micromixers under Different Angles and Velocities of the Incoming Water

Proceedings ◽  
2018 ◽  
Vol 2 (11) ◽  
pp. 577 ◽  
Author(s):  
Evangelos Karvelas ◽  
Christos Liosis ◽  
Theodoros Karakasidis ◽  
Ioannis Sarris
Keyword(s):  
Stokes Equations ◽  
Velocity Ratio ◽  
The Other ◽  
Navier Stokes ◽  
Contaminated Water ◽  
Solution Flow ◽  
Navier Stokes Equations ◽  
Inlet Velocity ◽  
Metal Capture ◽  
Discrete Motion

A possible solution for water purification from heavy metals is to capture them by using nanoparticles in microfluidic ducts. In this technique, heavy metal capture is achieved by effectively mixing two streams, a nanoparticle solution and the contaminated water. In the present work, particles and water mixing is numerically studied for various inlet velocity ratios and inflow angles of the two streams. The Navier-Stokes equations are solved for the water flow while the discrete motion of particles is evaluated by a Lagrangian method. Results showed that as the velocity ratio between the inlet streams increases, by increasing the particles solution flow, the mixing of particles with the contaminated water is increased. Thus, nanoparticles are more uniformly distributed in the duct. On the other hand, angle increase between the inflow streams ducts is found to be less significant.

scholarly journals Surface Morphology and Microstructure Evolution of Single Crystal Diamond during Different Homoepitaxial Growth Stages

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 5964
Author(s):  
Guoqing Shao ◽  
Juan Wang ◽  
Shumiao Zhang ◽  
Yanfeng Wang ◽  
Wei Wang ◽  
...  
Keyword(s):  
Surface Morphology ◽  
Single Crystal ◽  
Cross Section ◽  
Growth Model ◽  
Diamond Growth ◽  
Step Flow ◽  
Homoepitaxial Growth ◽  
Diamond Substrate ◽  
Single Crystal Diamond ◽  
Step Flow Growth

Homoepitaxial growth of step-flow single crystal diamond was performed by microwave plasma chemical vapor deposition system on high-pressure high-temperature diamond substrate. A coarse surface morphology with isolated particles was firstly deposited on diamond substrate as an interlayer under hillock growth model. Then, the growth model was changed to step-flow growth model for growing step-flow single crystal diamond layer on this hillock interlayer. Furthermore, the surface morphology evolution, cross-section and surface microstructure, and crystal quality of grown diamond were evaluated by scanning electron microscopy, high-resolution transmission electron microcopy, and Raman and photoluminescence spectroscopy. It was found that the surface morphology varied with deposition time under step-flow growth parameters. The cross-section topography exhibited obvious inhomogeneity in crystal structure. Additionally, the diamond growth mechanism from the microscopic point of view was revealed to illustrate the morphological and structural evolution.

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