论文标题:薄膜生长的理论模型和蒙特卡罗模拟
Model and Monte Carlo Simulation of Thin Film Growth
论文作者 杨宁
论文导师 陈光华,论文学位 硕士,论文专业 凝聚态物理
论文单位 北京工业大学,点击次数 92,论文页数 58页File Size3144k
2000-05-01论文网 http://www.lw23.com/lunwen_416346727/ YBCO,Ag单晶,双轴织构Ag基带, 外延生长理论,近似晶格匹配理论
YBCO,Ag singlerystal,biaxially textured Ag tapes,epitaxial growth,Near-coincident site lattice (NCSL) models
晶体材料是一类重要的功能材料，在当代高技术中有着极其重要的应用。研究晶体生长的理论对于发展新性能的新型晶体及提高传统晶体的质量和改性有着一定的指导作用。基于计算机技术而发展的数学建模和模拟是晶体生长理论研究的一类重要方法。本研究论文参考已有的生长模型，结合晶体生长理论及实验结果，建立了研究薄膜生长初期过程的模型，用蒙特卡罗（Monte Carlo）方法对薄膜的生长进行了二维和三维的模拟，所得许多有意义的结果。 在本模型中，粒子间的相互作用采用Morse势描述，其中的相互作用范围α对薄膜的生长有较大的影响。在α较小时，薄膜趋向于成团生长，生长过程明显经历了临界核的形成、粒子团的长大、形成迷津结构及连续成膜等阶段。而α较大时，粒子不易形成粒子团，其生长表现出层状生长的特性。 在各粒子团的生长过程曲线中，发现某些团尺寸的粒子数所占比重与团尺寸成线性关系，且各直线之间近似满足二分角关系，这在α=2时很明显，而α=6时，二分角关系不明显。 通过对二维生长和三维生长的相互验证，发现在α=2时，当第一层的覆盖率不是很高时，第二层就已经开始生长，而对此的不同处理方法，会对模拟结果产生不同的影响。
Crystal materials, an important function material, have an important application in modern high-technique. The theory of crystal growth is guidance for developing a new-type crystal and improving the properties of custom crystal. Modeling and simulation based on computer technology has been an important method for studying on crystal growth. In this article, the model of the early stage of thin film growth has been instituted based on the experiment results and by using the theory of crystal growth. Two-dimension growth and three1dimension growth process of thin films have been simulated using Monte Carlo method. Parameters of the structure of thin films have been studies, and research results are in good agreement to the experimental results. The interaction between particles has been investigated using Morse potential in which the range of the interaction i.e. a has more influence on the morphology of the films. When a is small, it is island growth and growth of films evolves four stages including formation of critical nucleation, growth of clusters, formation of maze structure and appearance of continuous film. When a is larger, it is layer growth. The plots of the growth process of clusters reveal that the percentage of the number of particles about a certain cluster size is linear with the cluster size and at an angle each other when a is 2. But it is not clear when a is 6. Two-dimension growth and three-dimension growth of the films have been simulated. At a2, the second layer is beginning growth when the coverage of the first layer is not high. So the different model has different results.
|
