分子束外延中自发生长GaN纳米线的自调节半径
Self-regulated radius of spontaneously formed GaN nanowires in molecular beam epitaxy
AI总结：
本研究通过改变Ga通量实验并结合动力学模型，揭示了GaN纳米线半径的自调节机制，解释了富N条件及III/V比影响半径的实验现象。
摘要：
我们研究了在分子束外延生长过程中，改变Ga通量对GaN纳米线轴向和径向生长的影响。增加Ga通量会促进径向生长，而不影响轴向生长速率。相反，减少Ga通量会降低轴向生长速率，而半径不变。这些结果由一个动力学生长模型解释，该模型考虑了Ga吸附原子沿侧面向纳米线尖端扩散以及可用于生长的活性N的有限量。该模型解释了增加Ga通量后形成新的平衡纳米线半径，并为两个已知但迄今未理解的实验事实提供了解释：有效富N条件对GaN纳米线自发形成的必要性，以及纳米线半径随III/V通量比增加而增大。
英文摘要：
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 towards 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 ratios.
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