边缘增强生长诱导GaN纳米壁网络形状转变
Edge enhanced growth induced shape transition in the formation of GaN Nanowall Network
摘要：
我们解决的机制的早期阶段的生长和形状转变的独特的纳米结构的GAN的纳米网络（NwN）通过实验监测其控制生长使用PA-分子束外延和补充它的\textit{first-principles}计算。使用电子显微镜，我们观察到四面体形状（3面金字塔）的岛屿的形成在生长的早期阶段，随后沿（20 $\overline{2}$ 1）面的边缘各向异性生长，形成壁状结构。根据不同表面的表面自由能、Ga原子在（20 $\overline{2}$ 1）晶面上的吸附能和扩散势垒讨论了这种晶体生长的机理。通过\textit{first-principles}计算，我们发现原子的扩散势垒随着小面宽度的减小而减小，这是导致原子各向异性生长和形成网状结构的主要原因。这项研究表明，NwN的形成是一个原型的例子结构依赖的附着动力学（SDAK）不稳定性诱导形状转变的薄膜生长。
英文摘要：
We address the mechanism of early stages of growth and shape transition of the unique nanowall network (NwN) nanostructure of GaN by experimentally monitoring its controlled growth using PA-MBE and complementing it by \textit{first-principles} calculations. Using electron microscopy, we observe the formation of tetrahedron shaped (3 faced pyramid) islands at early stages of growth, which later grows anisotropically along their edges of the (20$\overline{2}$1) facets, to form the wall like structure. The mechanism of this crystal growth is discussed in light of surface free energies of the different surfaces, adsorption energy and diffusion barrier of Ga ad-atoms on the (20$\overline{2}$1) facets. By \textit{first-principles} calculations, we find that the diffusion barrier of ad-atoms decreases with decreasing width of facets, and is responsible for the anisotropic growth and formation of the nanowall network. This study suggest that formation of NwN is a archetype example of structure dependent attachment kinetic (SDAK) instability induced shape transition in thin film growth.
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