摘要
本文较全面地从理论上研究了薄膜生长过程中原子在表面上的各种动力学表现 ,涉及的内容包括亚单层生长时 ,原子在表面上的扩散 ,粘接 ,成核 ,以及已经形成的原子岛之间的相互作用 ,兼并 ,失稳 ,退化等一系列过程。作为研究的基础 ,在本文的第一部分 (即0～ 6章 )中 ,我们首先介绍了目前这方面理论研究中所主要使用的各种方法。例如 ,第一性原理计算 ,分子动力学模拟 ,蒙特卡罗模拟 ,速率方程和过渡态 (TST)理论等。基于这些研究 ,我们介绍给读者为什么原子成岛时在低温下选择分形状 ,而在高温时则选择紧致状。这一过程可以用经典的扩散子限制集聚理论 (Diffusion_LimitedAggregation ,DLA)。然而当有表面活性剂存在时形核的规律完全相反 ,由此提出了一个反应限制集聚理论 (Reaction_LimitedAggregation,RLA)。这两个理论目前可以很好地解释亚单层生长时的一般形核规律。接下来我们讨论了长程相互作用对生长初期原子形核的影响 ,并进一步得出了相应的标度理论。在第 6章我们系统地研究了分了吸附对二维原子岛形状的控制性 ,从而提出了边 角原子扩散的对称破缺模型。
A systematic study of the kinetic and dynamic behavior of surface atoms during film growth is presented. The paper investigates the diffusion, attachment, and nucleation of the atoms on surface, as well as the interaction, aggregation, instability, and decay of the formed islands in submonolayer growth. At first, we study various theoretical methods, such as ab-initio calculations, molecular dynamics, kinetic Monte Carlo simulation, rate equation theory, and transition state theory (TST). In the Part I, from chapter 0 to 6, a novel model for reaction limited aggregation (RLA) is introduced to study the effect of a monolayer surfactant on the formation of two-dimensional islands in epitaxy. The key finding of the RLA theory is a counterintuitive fractal-to-compact island shape transition can be induced either by increasing deposition flux or by decreasing growth temperature, which is contrary to the predication of the classic diffusion-limited-aggregation (DLA) theory. The long-term interaction of atoms on surface has been discussed to see its influence on the formation and evolution of two-dimensional islands. The microscopic selection mechanisms of single-layer island shapes in the presence of impurity, for example of Pt(111) homoexpitaxy with or without CO adsorption, is also investigated. It is found that the orientation of the triangular islands is uniquely determined by the edge-to-corner rate anisotropy.
出处
《物理学进展》
CSCD
北大核心
2003年第1期1-61,共61页
Progress In Physics
基金
国家重点基础研究 973计划 (G2 0 0 0 0 671 0 3)
国家高技术 863计划 (2 0 0 2AA31 1 1 51 )
国家基金委"创新研究群体"(60 0 2 1 4 0 3)
国家基金委面上项目 (1 99740 69)
国家基金委重点项目(1 0 1 340 30 )
关键词
表面动力学
薄膜生长
纳米结构
形核理论
原子扩散
surface kinetics
thin film growth
nano-structure
aggregation theory
atomic diffusion
