Atomistic Mechanisms and Diameter Selection during Nanorod Growth
Atomistic Mechanisms and Diameter Selection during Nanorod Growth
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DOI：
10.1021/jp1060528
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发表时间：
2010-02
影响因子：
3.7
通讯作者：
D. Shu;X. Xiong;Zhaowu Wang;Zhenyu Zhang;Mu Wang;N. Ming
中科院分区：
文献类型：
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作者：
D. Shu;X. Xiong;Zhaowu Wang;Zhenyu Zhang;Mu Wang;N. Ming
本文研究了纳米棒生长的原子机制，提出了纳米棒直径选择的机制。一个特征半径被证明是至关重要的纳米棒的生长。如果二维核的临界尺寸被假定为1，特征半径增加成比例的1/5幂的比率的层间跳跃速率的吸附原子跨越单层台阶的沉积速率。当初始岛的半径大于该特征半径时，屏蔽效应对于纳米棒生长是重要的。生长形态从锥状结构演变为纳米棒的半径等于特征半径后，一些过渡层，这取决于屏蔽强度。当初始岛的半径小于该特征半径时，纳米棒的形貌可以在生长过程中保持，稳定的半径受到初始岛的半径和三维Ehrlich-Schwoebel势垒的限制。因此，通过控制生长条件，改变纳米棒的特征半径，可以选择不同的生长方式和纳米棒的直径。理论预测与ZnO生长的实验观察结果吻合得很好。
We study in this paper the atomic mechanisms of nanorod growth and propose the mechanism of diameter selection of nanorods. A characteristic radius is demonstrated to be crucial in nanorod growth. If the critical size of the two-dimensional nucleus is assumed to be 1, the characteristic radius increases proportional to 1/5 power of the ratio of the interlayer hopping rate of adatoms across the monolayer steps to the deposition rate. When the radius of the initial island is larger than this characteristic radius, a screening effect is important for nanorod growth. The growth morphology evolves from a taper-like structure to a nanorod with a radius equal to the characteristic radius after some transient layers, depending on the screening strength. When the radius of the initial island is smaller than this characteristic radius, the nanorod morphology can be maintained during the growth, with the stable radius being limited by both the radius of the initial island and the threedimensional Ehrlich-Schwoebel barrier. Therefore, different growth modes and the diameter of nanorod can be selected by changing the characteristic radius, via controlling the growth condition. The theoretical predictions are in good agreement with experimental observations of ZnO growth.