THEORETICAL STUDY ON DYNAMICS OF ATOMIC ARRANGEMENT AT STEPS

原子逐步排列动力学的理论研究

基本信息

批准号：
13640326
负责人：
KAWAMURA Takaaki
金额：
$ 2.11万
依托单位：
University of Yamanashi
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

项目摘要

We have studied behavior of steps and effect of steps in growth and decay of islands on a surface using a kinetic Monte Carlo simulation. We have also developed a reflection high energy electron diffraction (RHEED) code which calculates a wave function in a crystal in order to analyze atomic structures around steps.Our prime results are summarized as follows.1)We reveal that surface diffusion is not a simple process. When an island on a terrace decays, an atom at a step of the island moves out of it, but it is quite rare for the atom to move directly to a step away from the island. An atom hopping from the terrace and the resulting atomic vacancy play an important role ; once it hops out of the terrace, there is no distinction between a diffusing atom from the island and the hop-up atom.2)We reveal a change in a role of step during formation of an island on Si(100)-2 x1 terrace. A so-called Sb-type step acts as a drain of diffusing atoms before formation of an island but it acts as a source after starting the formation. The change of role promotes the island formation.3)Decay of an island is interpreted as a process of decreasing the step length and total hopping rate of atoms. As the hopping rate of atom at step is higher than that on terrace, a step atom moves more frequently to reduce the number of step atoms.4)We have shown that under surface resonance condition, a RHEED wave function is quite localized at the surface. The localization occurs as a result of multiple scattering of surface waves which propagate nearly parallel to the surface.

我们使用动力学蒙特卡罗模拟研究了表面岛屿生长和衰变的阶梯行为和阶梯效应。我们还开发了反射高能电子衍射 (RHEED) 代码，用于计算晶体中的波函数，以便分析台阶周围的原子结构。我们的主要结果总结如下。1) 我们揭示了表面扩散并不是一个简单的过程过程。当台上的岛衰变时，岛台阶处的原子会移出岛外，但原子直接移至距离岛一步的情况很少见。从平台跳跃的原子和由此产生的原子空位起着重要作用；一旦它跳出平台，来自岛的扩散原子和跳跃原子之间就没有区别。2）我们揭示了在 Si(100)-2 x1 上形成岛期间步骤角色的变化阳台。所谓的Sb型台阶在形成岛之前充当扩散原子的漏极，但在开始形成之后充当源。角色的变化促进了岛的形成。3)岛的衰变被解释为原子步长和总跳跃率减小的过程。由于台阶上的原子跳跃率高于平台上的原子跳跃率，台阶原子移动更频繁，以减少台阶原子的数量。4)我们已经证明，在表面共振条件下，RHEED波函数在表面相当局域化。。局部化是由于几乎平行于表面传播的表面波的多次散射而发生的。