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.

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.

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.

Effect of Melt-Back Process on the Quality of Grown Crystal in SiC Solution Growth

2019 ◽  
Vol 963 ◽  
pp. 75-79 ◽  
Author(s):  
Kotaro Kawaguchi ◽  
Kazuaki Seki ◽  
Kazuhiko Kusunoki
Keyword(s):  
Dislocation Density ◽  
Grown Crystal ◽  
Early Stage ◽  
Seed Crystal ◽  
Solution Growth ◽  
Crystal Quality ◽  
Top Seeded Solution Growth ◽  
Koh Etching

We investigated the effect of a melt-back process on the quality of the grown crystal in 4H-SiC solution growth. In our experiments, the crystal was grown by top-seeded solution growth (TSSG) method with and without melt-back, following which the quality of the obtained crystals was compared. When solution growth was carried out without melt-back, solvent inclusions and a different polytype were observed. When molten KOH etching was conducted, the dislocation density in the crystals at the early stage of growth became much higher than that in a seed crystal. Solvent inclusions, a different polytype, and an increase in dislocations were suppressed when solution growth was performed with melt-back. It was confirmed that melt-back is necessary to prevent the deterioration of crystal quality at the early stage of solution growth.

Solution Growth of SiC from the Crucible Bottom with Dipping under Unsaturation State of Carbon in Solvent

2018 ◽  
Vol 924 ◽  
pp. 51-54
Author(s):  
Toshinori Taishi ◽  
Masaru Takahashi ◽  
Naomichi Tsuchimoto ◽  
Koki Suzuki ◽  
Koang Yong Hyun
Keyword(s):  
Growth Temperature ◽  
Growth Conditions ◽  
Solution Growth ◽  
Step Flow ◽  
Crucible Bottom ◽  
Top Seeded Solution Growth ◽  
Dipping Time ◽  
Bottom Step

SiC crystals are grown using a Si-Cr-based solvent by a top-seeded solution growth (TSSG) method by changing the dipping time after when the growth temperature is reached. Step-flow-like curve morphologies were observed for a dipping time after 15 min, while polycrystallization occurred at the periphery for that after 120 min, which corresponded to the dipping under unsaturated and supersaturated carbon in the solvent, respectively. Furthermore, the solution growth of SiC with dipping under unsaturated carbon was easily realized by the growth from the crucible bottom, step-flow-like growth was achieved. Using this technique, dominant polytypes of SiC in various growth conditions after stable seed dipping under the unsaturation in the solvent can be demonstrated.

Top-Seeded Solution Growth of 4H-SiC Bulk Crystal Using Si-Cr Based Melt

2012 ◽  
Vol 717-720 ◽  
pp. 61-64 ◽  
Author(s):  
Hironori Daikoku ◽  
M. Kado ◽  
H. Sakamoto ◽  
Hiroshi Suzuki ◽  
T. Bessho ◽  
...  
Keyword(s):  
Growth Rate ◽  
Seed Crystal ◽  
Solution Growth ◽  
Bulk Crystals ◽  
High Quality ◽  
Cross Sectional ◽  
Formation Technique ◽  
Top Seeded Solution Growth ◽  
Microscopy Images

We have grown high-quality long cylindrical (12 mm thick) 4H-SiC bulk crystals by the meniscus formation technique, which was first applied for the solution growth of bulk SiC. It enabled long-term growth by suppressing parasitic reactions such as polycrystal precipitation around the seed crystal. In addition, we could control the growth angle from −22° to 61° by adjusting the meniscus height. The thickness of the grown cylindrical crystals was 12 mm, which is the largest reported until now, and corresponded to a growth rate of 0.6 mm/h. Smooth morphology growth was maintained on the (000-1) C-face. In cross-sectional transmission optical microscopy images, few solvent inclusions and voids were observed. XRD measurements revealed that the FWHM values of the grown crystals were almost the same as those of the seed crystal.

Reduction of Threading Screw Dislocation Utilizing Defect Conversion during Solution Growth of 4H-SiC

2013 ◽  
Vol 740-742 ◽  
pp. 189-192 ◽  
Author(s):  
S. Harada ◽  
Yuji Yamamoto ◽  
Kazuaki Seki ◽  
Toru Ujihara
Keyword(s):  
Screw Dislocation ◽  
Seed Crystal ◽  
Solution Growth ◽  
Spiral Growth ◽  
High Quality ◽  
Special Shape ◽  
Screw Dislocations ◽  
Step Flow ◽  
Polytype Transformation ◽  
Step Flow Growth

Reduction of threading screw dislocation without polytype transformation from 4H-SiC was performed by the combination of step-flow growth and spiral growth. On a vicinal 4H-SiC seed crystal, threading screw dislocations are converted to Frank-type stacking faults by step-flow during solution growth. As the growth proceeds, the defects are excluded to the crystal. Thus utilizing the conversion, high quality SiC crystal growth without threading screw dislocations is expected to achieve. However, at the same time, polytype transformation is caused by the occurrence of 2D nucleation. By using the special shape of seed crystal, we successfully grew high quality 4H-SiC crystal without threading screw dislocation and polytype transformation.

YMgB5O10 crystal preparation and attractive multi-wavelength emission characteristics of doping Nd3+ ions

2021 ◽  
Author(s):  
Shijia Sun ◽  
Qi Wei ◽  
Bing-Xuan Li ◽  
Xingjun Shi ◽  
feifei yuan ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Transmission Spectrum ◽  
Systematic Investigation ◽  
Solution Growth ◽  
Emission Characteristics ◽  
Multi Wavelength ◽  
Growth Method ◽  
Wavelength Emission ◽  
Spectrum Band ◽  
Top Seeded Solution Growth

The pure and Nd3+-doped YMgB5O10 (YMB, Nd:YMB) crystals were grown successfully by the top-seeded solution growth method with composite fluxes Li2O-B2O3-LiF. The systematic investigation of crystal structure, transmission spectrum, band...

Growth of Ti alloyed Nb3Sn crystals from Sn-Ti-Nb solutions by top seeded solution growth

1986 ◽  
Vol 78 (3) ◽  
pp. 567-570 ◽  
Author(s):  
T. Inoue ◽  
H. Komatsu ◽  
M. Shimizu ◽  
S. Tsunekawa ◽  
H. Takei
Keyword(s):  
Solution Growth ◽  
Top Seeded Solution Growth
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