Enhancement of island size by dynamic substrate disorder in simulations of graphene growth.
Enhancement of island size by dynamic substrate disorder in simulations of graphene growth.
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DOI：
10.1039/c6cp00788k
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发表时间：
2016-06
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影响因子：
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通讯作者：
Gwilym Enstone;P. Brommer;D. Quigley;Gavin R Bell
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文献类型：
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作者：
Gwilym Enstone;P. Brommer;D. Quigley;Gavin R Bell
我们展示了一种新的机制，在亚单层外延岛生长的早期阶段，使用Monte Carlo模拟实验观察铜箔上的石墨烯生长的动机。在我们的模型中，基板是“动态粗糙”，这意味着（i）Cu和C之间的相互作用强度随机变化，从网站到网站，和（ii）这些可变的强度本身迁移从网站到网站。动态粗糙度提供了在真实的石墨烯生长的情况下Cu衬底的近熔融状态的简单表示。反直觉地，与静态且光滑的基底相比，当包括动态粗糙度时，石墨烯岛的尺寸增加。我们将这种效应归因于衬底中的波动使小的石墨烯岛不稳定，使它们分裂并加入更大的岛，这些岛对粗糙度更稳定。在静态粗糙度的情况下，当过程（ii）被关闭时，岛的生长被强烈抑制和无标度行为的岛屿尺寸分布，目前在光滑静态和粗糙动态的情况下，被破坏。动态基板粗糙度的影响不能模仿的静态情况下的参数变化。
We demonstrate a new mechanism in the early stages of sub-monolayer epitaxial island growth, using Monte Carlo simulations motivated by experimental observations on the growth of graphene on copper foil. In our model, the substrate is "dynamically rough", by which we mean (i) the interaction strength between Cu and C varies randomly from site to site, and (ii) these variable strengths themselves migrate from site to site. The dynamic roughness provides a simple representation of the near-molten state of the Cu substrate in the case of real graphene growth. Counterintuitively, the graphene island size increases when dynamic roughness is included, compared to a static and smooth substrate. We attribute this effect to destabilisation of small graphene islands by fluctuations in the substrate, allowing them to break up and join larger islands which are more stable against roughness. In the case of static roughness, when process (ii) is switched off, island growth is strongly inhibited and the scale-free behaviour of island size distributions, present in the smooth-static and rough-dynamic cases, is destroyed. The effects of the dynamic substrate roughness cannot be mimicked by parameter changes in the static cases.