Paul-Drude-Institut für Festkörperelektronik , Hausvogteiplatz 5-7, 10117 Berlin, Germany.
Nano Lett. 2013 Jul 10;13(7):3274-80. doi: 10.1021/nl401483e. Epub 2013 Jun 17.
We investigate the axial and radial growth of GaN nanowires upon a variation of the Ga flux during molecular beam epitaxial growth. An increase in the Ga flux promotes radial growth without affecting the axial growth rate. In contrast, a decrease in the Ga flux reduces the axial growth rate without any change in the radius. These results are explained by a kinetic growth model that accounts for both the diffusion of Ga adatoms along the side facets toward the nanowire tip and the finite amount of active N available for the growth. The model explains the formation of a new equilibrium nanowire radius after increasing the Ga flux and provides an explanation for two well-known but so far not understood experimental facts: the necessity of effectively N-rich conditions for the spontaneous growth of GaN nanowires and the increase in nanowire radius with increasing III/V flux ratio.
我们研究了分子束外延生长过程中 Ga 通量变化时 GaN 纳米线的轴向和径向生长。Ga 通量的增加促进了径向生长，而不影响轴向生长速率。相反，Ga 通量的减少会降低轴向生长速率，而半径没有任何变化。这些结果可以通过一个动力学生长模型来解释，该模型考虑了 Ga 原子沿纳米线尖端的侧面对扩散以及用于生长的有限量的活性 N。该模型解释了增加 Ga 通量后新的平衡纳米线半径的形成，并为两个众所周知但迄今为止尚未理解的实验事实提供了解释：有效富 N 条件对 GaN 纳米线自发生长的必要性以及随着 III/V 通量比的增加纳米线半径增加。
