Turning off Hydrogen To Realize Seeded Growth of Subcentimeter Single-Crystal Graphene Grains on Copper
Turning off Hydrogen To Realize Seeded Growth of Subcentimeter Single-Crystal Graphene Grains on Copper
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DOI：
10.1021/nn404393b
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发表时间：
2013-10-01
期刊：
影响因子：
17.1
通讯作者：
Luo, Zhengtang
中科院分区：
文献类型：
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作者：
Gan, Lin;Luo, Zhengtang
通过调节大气压化学气相沉积过程中的成核密度，成功地合成了直径达5.9 mm的亚厘米级单晶石墨烯颗粒。形态学研究表明，在这些石墨烯颗粒的几何中心存在单个大纳米颗粒（直径>类似于20 nm）。通过在仅Ar环境中轻微氧化铜表面以获得氧化物纳米颗粒，然后在H-2/Ar环境下还原成大的铜纳米颗粒来产生类似尺寸的颗粒，并且因此被解释为石墨烯生长的主要组成核。在此基础上，我们能够通过调节氧化程度和氢退火持续时间来控制纳米颗粒密度，从而控制成核密度，从而控制石墨烯晶粒尺寸。此外，我们发现氢在整个生长过程中对铜形态起着双重作用，即去除表面不规则性，同时蚀刻铜表面以产生对石墨烯生长的成核作用有限的小纳米颗粒。我们报告的方法为生产具有远程电子连接性和结构相干性的石墨烯薄膜提供了一种高效的方法。
Subcentimeter single-crystalline graphene grains, with diameter up to 5.9 mm, have been successfully synthesized by tuning the nucleation density during atmospheric pressure chemical vapor deposition. Morphology studies show the existence of a single large nanoparticle (>similar to 20 nm in diameter) at the geometric center of those graphene grains. Similar size particles were produced by slightly oxidizing the copper surface to obtain oxide nanoparticles in Ar-only environments, followed by reduction into large copper nanoparticles under H-2/Ar environment, and are thus explained to be the main constituent nuclei for graphene growth. On this basis, we were able to control the nanoparticle density by adjusting the degree of oxidation and hydrogen annealing duration, thereby controlling nucleation density and consequently controlling graphene grain sizes. In addition, we found that hydrogen plays dual roles on copper morphology during the whole growth process, that is, removing surface irregularities and, at the same time, etching the copper surface to produce small nanoparticles that have only limited effect on nucleation for graphene growth. Our reported approach provides a highly efficient method for production of graphene film with long-range electronic connectivity and structure coherence.