摘要
在垂直Bridgman晶体生长装置中,熔体的热质对流是由于温度梯度和浓度梯度间的相互作用引起的,而温度梯度和浓度梯度由晶体热物性和生长炉结构所决定.由于温度梯度和浓度梯度的耦合作用,坩埚中熔体的流动结构形式多样,由流动引起的溶质分布也呈多种形式。本文以GeSi多组元化合物半导体晶体为对象。数值研究了垂直Bridgman晶体生长过程中的热质对流现象,分析了热Rayleigh数、GeSi晶体热物性、生长炉结构对热质对流和径向溶质分凝的影响规律.结果表明:在垂直Bridgman装置中,熔体的热质对流是由于生长炉热边界条件的不连续性和晶体熔-固两相热物性不匹配引起的;随着熔体流动强度的增加,径向溶质分凝出现两个极小点,所以单纯地抑制或加强熔体对流强度并不一定能改善径向溶质分凝现象。
The thermosolutal convection during directional solidification of multi-element compound crystals alloy in vertical Bridgman configuration arises from the interaction between temperature and solute gradients in the bulk melt. Both the gradients are determined by the alloy＇s thermophysical properties and the design of the growth configuration. The flow patterns and the solute profiles caused by the thermosolutal convection have an extremely rich structure. In this paper, taking GeSi binary alloy for example, a numerical analysis of thermosolutal convection in vertical Bridgman furnace was performed to study the effects of thermal Rayleigh Number, thermophysical properties and the design parameters of growth configuration on the thermosolutal convection and radial solute segregation. The results showed that the flow in the melt is driven by both the discontinuity of thermal boundary conditions and the difference of the thermophysical properties between melt and crystal. Meanwhile, the radial solute segregation undergoes two minima when the intensity of flow increases. So, the measures that aim at reducing the intensity of thermosolutal convection may not improve the radial solute segregation.
出处
《工程热物理学报》
EI
CAS
CSCD
北大核心
2008年第4期653-658,共6页
Journal of Engineering Thermophysics
基金
国家自然科学基金重点(No.50336040)
新世纪优秀人才支持计划(No.NCET-04-0923)
关键词
垂直Bridgman装置
热质对流
温度梯度
径向溶质分凝
vertical Bridgman configuration
thermosolutal convection
temperature gradient
radial solute segregation
