如何生长具有特定空间几何结构的单层石墨烯

【作者】 陈斌；

【导师】 宁西京；

【作者基本信息】 复旦大学 ， 原子与分子物理， 2014， 硕士

【摘要】 石墨烯是只有单层原子厚度的二维材料,具有硬度高、导电性好、化学结构稳定等特性,自从2004年发现以来引起了广泛的研究兴趣,被期待发展出响应速度更快、线径更小的新一代电子元器件或晶体管而替代现有的硅基器件。然而由于石墨烯没有带隙,难以直接用于制作光电元器件。为了克服这一缺陷,通常的做法是在单层石墨烯上制造缺陷或掺杂其他原子。我们课题组提出了通过裁剪石墨烯制备单壁碳纳米锥的方法。理论研究表明这种碳锥在室温下的寿命可达1010年,并具有良好的单向电流导通性,可用作纳米二极管。然而,用这样的方法大规模制备碳锥在技术上仍然有很大困难。本文分析了单层石墨烯的生长过程,提出了一种制备具有特定几何构型石墨烯的方法,即在清洁晶体表面预先用物理化学方法(如离子束轰击或电解等)制备出具有期望几何形状(如圆锥、圆柱和半球等)的纳米坑,然后采用气相沉积方法在该表面生长单层石墨烯,最后得到的单层石墨烯应具有相应的几何结构。为了检验该方法的可行性,本文分别采用分子动力学模拟和一种全局势能优化方法——时间倒流方法具体研究了在Ni晶体表面实施的可行性。之所以选取Ni表面是因为它通常用作生长石墨烯的催化剂。结果表明,当表面纳米坑的横向线径大于0.8nm时,石墨烯的生长前沿便深入到坑内,最后生成的石墨烯具有类似于坑的几何形状；如果表面纳米坑的线径小于0.8nm,最后生成的石墨烯仅是平面结构。也就是说用这种方法可以制备具有1 nm线径以上特定几何构型的石墨烯,可望在我们组的后续实验中得到验证。更多还原

【Abstract】 Graphene as thin as single atomic thickness is very hard and stable in air and owns good thermal and electrical conductivity. Since discovered in 2004 it caused widespread research interest, graphene is expected to develop a faster, thinner next-generation transistors and electronic components in order to replace the existing silicon-based materials. However, since there is no energy gap of graphene, for the production of optoelectronic components is difficult to directly, in order to overcome this drawback, the usual approach has doped graphene structure defect structure other atoms. A single wall carbon nano cone could be prepared by tailoring single atom sheets of graphene, and can survive for 101 years at room temperature. Theoretical study shows that the cone composed of only tens carbon atoms has electrical rectification effect, that could be used to prepared the diode. But it is still very hard to large-scale product.Considering the growth process of graphene sheets, we except that arbitrary nanostructure can form in the growth process if some geometry shapes are pre-curved on surface of the substrate on which graphene grows. The feasibility was proved by molecular simulations and time-going-backward quasi-dynamics. Specifically, if some pits of definite shapes in nanoscaleis pre-curved on the surfaces of Ni or Cu crystal, then the graphene sheets grown on these surfaces will take on similar geometrical structure as long as the structure size is not smaller than 0.8 nanometers.更多还原