Effect of accelerated crucible rotation on segregation and interface morphology for vertical Bridgman crystal growth: visualization and simulation
Date Issued
2007
Date
2007
Author(s)
Liu, Yu-Cheng
DOI
en-US
Abstract
In vertical Bridgman (VB) crystal growth process, the solute uniformity of obtained crystal is very important but however segregation due to buoyancy force during binary solidification which affects dopant concentration severely is always inevitable. Accelerated crucible rotation technique (ACRT) and angular vibration technique (AVT) are both kind of accelerated crucible rotation, and the purpose of them is to vary melt flow field in during VB crystal growth. In several studies, the mechanism of ACRT in detail is not very clearly addressed, especially the interplay of spin-up and spin-down flow in one ACRT cycle. AVT is a novel method which was proposed and demonstrated by our group in these two years, so there are rare literatures concerning this subject. In this study, both of lighter (acetone) and heavier (salol) solute are added in succinonitrile (SCN) sample to observe how different dopant affects interface morphology during directional solidification. The effect of different intensity ACRT and AVT on interface morphology is also investigated for these two samples. By the implement of numerical simulation, interface morphology, flow intensity and direction, and concentration field give very good agreement with experimental observation. To modify the condition of segregation, ACRT enhances radial and global mixing of solute in the meanwhile and compensates with larger concavity of interface. AVT enhances only radial mixing of solute, and more planar interface can be obtained. In view of crystal growth, comparison of ACRT and AVT results establishes AVT to be superior scheme for VB crystal growth in terms of segregation control and interface morphology.
Subjects
垂直布氏法
偏析
加速坩堝旋轉
界面
vertical Bridgman
segregation
accelerated crucible rotation
interface morphology
Type
thesis
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