Nucleation and growth of single layer graphene on electrodeposited Cu by cold wall chemical vapor deposition
Nucleation and growth of single layer graphene on electrodeposited Cu by cold wall chemical vapor deposition
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DOI：
10.1088/1361-6528/aa593b
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发表时间：
2017-03-10
期刊：
影响因子：
3.5
通讯作者：
Drucker, Jeff
中科院分区：
文献类型：
--
作者：
Das, Shantanu;Drucker, Jeff
采用冷壁化学气相沉积（CVD）技术，在4 μ m厚的Cu薄膜上生长的石墨烯晶体的成核密度和平均尺寸可以通过不同的生长参数来调节。在固定的衬底温度为1000℃，总压为700 Torr的条件下，利用Ar、H-2和CH4混合物生长，可以确定总流速、CH4:H-2比和Ar对CH4/H-2混合物稀释的贡献。CH4:H-2比的变化对成核密度的影响最大。观察到的形态变化类似于在固定衬底温度下使用热蒸发进行物理沉积时沉积速率变化所期望的形态变化。随着有效碳沉积速率的降低，石墨烯晶界形态从不规则/锯齿状→凸六边形→正六边形。这一观察结果表明，除了H-2蚀刻外，C原子沿晶界的边缘扩散可能有助于石墨烯晶体的形状演变。这些结果表明，使用冷壁CVD生长的石墨烯遵循与热壁CVD相似的成核和生长机制。因此，与热壁CVD相关的庞大知识库可以通过工业上较好的冷壁方法用于石墨烯合成。
The nucleation density and average size of graphene crystallites grown using cold wall chemical vapor deposition (CVD) on 4 mu m thick Cu films electrodeposited on W substrates can be tuned by varying growth parameters. Growth at a fixed substrate temperature of 1000 degrees C and total pressure of 700 Torr using Ar, H-2 and CH4 mixtures enabled the contribution of total flow rate, CH4:H-2 ratio and dilution of the CH4/H-2 mixture by Ar to be identified. The largest variation in nucleation density was obtained by varying the CH4:H-2 ratio. The observed morphological changes are analogous to those that would be expected if the deposition rate were varied at fixed substrate temperature for physical deposition using thermal evaporation. The graphene crystallite boundary morphology progresses from irregular/jagged through convex hexagonal to regular hexagonal as the effective C deposition rate decreases. This observation suggests that edge diffusion of C atoms along the crystallite boundaries, in addition to H-2 etching, may contribute to shape evolution of the graphene crystallites. These results demonstrate that graphene grown using cold wall CVD follows a nucleation and growth mechanism similar to hot wall CVD. As a consequence, the vast knowledge base relevant to hot wall CVD may be exploited for graphene synthesis by the industrially preferable cold wall method.