多晶铜氧化衬底对大单晶石墨烯生长成核抑制机制的研究

Graphene, a two-dimension material of atomic thickness, has excellent properties in electrics, optics, mechanics, etc. However, these properties would be severely degraded by defects in graphene sheet, therefore, how to diminish or even avoid the defects in graphene is a challenge that attracted much attention from the whole world. Generally, the defects are mainly concentrated along the grain boundaries in graphene sheet in which the whole sheet is consisted of a large number of small sized single crystalline graphene grains. Currently, synthesis of large sized single crystalline graphene grain via chemical vapor deposition is a promising strategy to face the challenge where the main idea is to increase the size of single crystalline graphene grain and thus decrease the boundaries number and also diminish the defects in graphene sheet, therefore, the final quality of graphene sheet would be improved. Recently, oxidized polycrystalline copper was confirmed to be a highly efficient substrate for large sized graphene grains synthesis, which can suppress the nucleation density of graphene drastically compared with that on any type of as-purchased polycrystalline copper substrates. However, the exact suppression mechanism for oxidized polycrystalline copper is still under debate. In my previous work, a copper nanoparticle seeded growth mechanism has been proposed to explain the suppression effect. In this project, we are going to further explore the detailed mechanism through various methods to modify the copper surface for nanoparticle forming, combined with the statistics information of nanoparticles size/dispersion and in-situ characterization technique. An optimized copper nanoparticle forming condition and large sized single crystalline graphene grains growth condition would be explored，in company with building of related evolution models. Moreover, the relation between graphene layer number, nanoparticle size/morphology, and copper substrate facet would be systematically studied. Based on this, centimeter-above sized single crystalline graphene grain synthesis and a control growth in graphene layer number are expected goals.

石墨烯因其优异的各项性能而广受关注，然而，其优异性能往往受到来自面内晶格缺陷的负面影响。晶格缺陷通常产生在石墨烯面内单晶畴区之间的晶界处。大单晶石墨烯化学气相沉积法生长是目前解决这一问题的一种有效手段，其原理是通过增大石墨烯单晶的尺寸，从而减小石墨烯中晶界的数量，进而达到减少晶格缺陷的目的。近年来，多晶铜氧化衬底对石墨烯生长表现出了非常优异的成核抑制作用，但其具体的原理却一直存有争议。在前期工作中，本人提出了铜纳米颗粒诱导生长机制对此现象进行解释。本课题在此基础上，将通过多种方式对多晶铜表面进行预处理以产生铜纳米颗粒，建立纳米颗粒随预处理和生长条件的演化模型；结合系统分析和原位表征等手段深入研究铜纳米颗粒、铜晶面取向和石墨烯成核形貌/层数之间的关系，对本人前期提出的铜纳米颗粒诱导成核机制进一步探讨，以期能够对此机理有更系统深入地理解，同时实现厘米级以上尺寸的石墨烯大单晶层数可控制备。

申请人在氧化铜箔表面纳米颗粒诱导成核机制以及二维材料化学气相沉积可控制备方面取得了以下成果：（1）基于纳米颗粒机制实现了大面积严格单层石墨烯的制备，并进一步将此机制的应用推广至h-BN大单晶的生长；（2）利用化学气相沉积方法实现了多种层状、非层状和复杂晶相的二维材料单晶和薄膜的可控生长；（3）基于二维材料复合结构，实现了响应光谱范围拓宽、光谱响应选择性及快速光谱响应的高性能光探测器。在Adv. Mater.，Adv. Funct. Mater., Small, Nanoscale以及Nano Research等SCI期刊发表论文20余篇，其中一作/通讯论文13篇，申请获批专利1项，荣获湖北省“楚天学子”称号。本项目旨在进一步理解纳米颗粒成核生长机制，并将化学气相沉积方法应用于更多种类的二维材料可控制备。