Silicon carbide (SiC) is a wide band gap semiconductor material for future electronics in high-power, high-temperature, and high-frequency applications. Solution growth is a promising method to achieve high quality crystals because the growth proceeds under the condition close to the thermal equilibrium. Recently we revealed that threading dislocations are converted to basal plane defects by the step-flow during the solution growth. By utilizing the threading dislocation conversion, we achieved drastic reduction of dislocation density. However, during the solution growth, step bunching always occurs. By the step bunching, the excess development of macrosteps can lead to the macroscopic defects such as rough growth surface and solvent inclusion. In this study, for the reduction of the step bunching during the solution growth of SiC, we investigated the effect of solution flow velocity on the step bunching behavior.

SiC crystal growth was conducted by the specially designed top seeded solution growth (TSSG) configuration. In our growth experiment, the seed crystals were placed at the position deviated from the center of the crucible. By only rotating the crucible, controlled solution flow was obtained on the growth surface. In this study, the off-angled 4H-SiC was used as seed crystals. We carried out the growth under two different solution flows, in which the solution flow direction and step-flow direction was the same (here we call parallel flow) and opposite (anti-parallel flow). 

As shown in Figure 1, wide and flat macro-terraces were frequently observed under the parallel flow, while the step trains with narrow macro-terraces were observed under the anti-parallel flow. Figure 2 shows that the surface roughness of the grown crystal under the parallel flow was larger than that of anti-parallel flow. Under the parallel flow, the surface roughness increases with increasing solution flow velocity. On the other hand, the surface roughness was independent of the solution flow velocity under the anti-parallel flow. This can be explained by the change of solute concentration distribution above the crystal surface which controls the behavior of step bunching. Under the parallel flow, the high-concentration solution moves to the edge of macro-terrace, which results in the microsteps run into the macrosteps quickly and then the surface roughness increases. While under the anti-parallel flow, the high-concentration solution moves to the macrosteps from the front direction, thus the microsteps run out of the macrosteps, which keeps the surface roughness stable. We figured out that the solution flow control could be an effective way to control step bunching during the solution growth of SiC.

Acknowledgement: This study was partly supported by Novel Semiconductor Power Electronics Project Realizing Low Carbon-Emission Society of Ministry of Economy, Trade and Industry through R&D Partner-ship for Future Power Electronics Technology (FUPET). 

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/28854 must be provided.

1. Two-dimensional crystallization of DNA-functionalized nanoparticles via lipid diffusion in supported lipid bilayers
2. Forming two-dimensional structure of DNA-functionalized Au nanoparticles via lipid diffusion in supported lipid bilayers
3. Growth of high quality 3C-SiC on hexagonal SiC seed using TSSG method
4. Growth rate and surface morphology of 4H-SiC crystals grown from Si-Cr-C based solutions under various temperature gradient conditions
5. Evolution of threading screw dislocation conversion during solution growth of 4H-SiC
6. Two Pathways Determining Chirality in NaClO₃ Crystals Grown from Solution via Achiral Precursors
7. Ultra-high quality SiC crystal grown by solution method utilizing the conversion from threading dislocations to basal plane defects