表面剂诱导外延中的形核生长及多重分形分析  

Nucleation behavior and multifractal analysis of early stage of surfactant-mediated epitaxial growth

作　　者：王竹平[1] 王戴木[2] 

机构地区：[1]安徽大学物理与材料科学学院,安徽合肥230039 [2]阜阳师范学院物理系,安徽阜阳236032

出　　处：《电子显微学报》2006年第3期221-225,共5页Journal of Chinese Electron Microscopy Society

基　　金：安徽省自然科学基金资助项目(No.050460201)~~

摘　　要：运用动力学蒙特卡罗(KMC)方法研究了表面剂诱导外延中岛的早期形核和生长行为。我们的模型包括三个主要的原子过程:增原子在表面剂台面上扩散、增原子与它下面的表面剂原子之间的位置交换(seed exchange形核换位)、已交换到衬底的增原子与它上面的表面剂原子交换位置重新回到表面剂台面(reexchange再换位)。模拟结果显示,在确定的沉积率下,形核密度N由于恢复交换随温度增加被激活而发生转变,对应的转变温度Tx将曲线N^T分成了两个不同的区域。在不同的温区,岛密度随沉积率的演变呈现不同的特性。多重分形谱用来定量表征不同生长条件下岛的分布。在转变温度T=Tx处,多重分形谱的宽度最小、顶值最高;随着温度的升高或降低,谱的宽度增大,顶值减小。Nucleation and growth behavior of two dimensional islands in early stage of surfactant-mediated epitaxial growth have been studied by Kinetic Monte Carlo （KMC） simulation. Our model includes three main atomic processes： diffusion of adatoms on the surfactant terrace, exchange of adatoms with their underneath surfactant atoms, and reexchange of exchanged adatoms with the lifted surfactant atoms for resurfacing to the top of the surfactant layer. The simulation results demonstrate that, with increasing temperature, the activated reexchange process gives rise to a transition of nucleation density. The evolutions of island density with temperature and deposition flux show different behavior in two different temperature regions, which are divided by the transition temperature Tx. Multifractal spectra are used to describe quantitatively the irregular distribution of island patterns obtained under different growth conditions. At the transition temperature T = Tx, the bell-like multifractal spectrum has a smaller width and a higher top value. As the temperature increased or decreased, The width of the spectra increases, while the top f（ α ） decreases.

关 键 词：KMC模拟 外延 分形 

分 类 号：O484.1[理学—固体物理] O242.2[理学—物理]