Defect-like structures of graphene on copper foils for strain relief investigated by high-resolution scanning tunneling microscopy.
Defect-like structures of graphene on copper foils for strain relief investigated by high-resolution scanning tunneling microscopy.
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DOI：
10.1021/nn200573v
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发表时间：
2011-04
期刊：
影响因子：
17.1
通讯作者：
Yanfeng Zhang;T. Gao;Yabo Gao;Shubao Xie;Qingqing Ji;Kai Yan;H. Peng;Zhongfan Liu
中科院分区：
文献类型：
--
作者：
Yanfeng Zhang;T. Gao;Yabo Gao;Shubao Xie;Qingqing Ji;Kai Yan;H. Peng;Zhongfan Liu
了解用化学气相沉积(CVD)方法在铜箔上生长的石墨烯的连续性和微观结构，对于优化生长参数以获得高质量的石墨烯具有重要意义。由于铜箔表面的波纹性质，到目前为止，关于这一问题的实验努力还很少。我们提出了一种高分辨率扫描隧道显微镜(STM)研究CVD石墨烯直接在铜箔上。我们的工作表明，石墨烯可以在晶区和非晶区以完美的连续性生长，这表明石墨烯-衬底之间的相互作用很弱。由于热膨胀失配，缺陷状褶皱和波纹倾向于沿着晶阶的边界或在非晶区演化以缓解应变。此外，完美的二维石墨烯与铜箔高波纹表面的整合所产生的应变效应导致了碳的局域成键构型从sp(2)到sp(3)的转变，形成了“六取三”晶格。
Understanding of the continuity and the microscopic structure of as-grown graphene on Cu foils through the chemical vapor deposition (CVD) method is of fundamental significance for optimizing the growth parameters toward high-quality graphene. Because of the corrugated nature of the Cu foil surface, few experimental efforts on this issue have been made so far. We present here a high-resolution scanning tunneling microscopy (STM) study of CVD graphene directly on Cu foils. Our work indicates that graphene can be grown with a perfect continuity extending over both crystalline and noncrystalline regions, highly suggestive of weak graphene-substrate interactions. Due to thermal expansion mismatch, defect-like wrinkles and ripples tend to evolve either along the boundaries of crystalline terraces or on noncrystalline areas for strain relief. Furthermore, the strain effect arising from the conforming of perfect two-dimensional graphene to the highly corrugated surface of Cu foils is found to induce local bonding configuration change of carbon from sp(2) to sp(3), evidenced by the formation of "three-for-six" lattices.