Department of Mechanical Engineering and the Materials Science and Engineering Program, The University of Texas at Austin, Austin, Texas 78712, United States.
ACS Nano. 2012 Sep 25;6(9):7731-8. doi: 10.1021/nn301689m. Epub 2012 Sep 4.
Strongly coupled bilayer graphene (i.e., AB stacked) grows particularly well on commercial "90-10" Cu-Ni alloy foil. However, the mechanism of growth of bilayer graphene on Cu-Ni alloy foils had not been discovered. Carbon isotope labeling (sequential dosing of (12)CH(4) and (13)CH(4)) and Raman spectroscopic mapping were used to study the growth process. It was learned that the mechanism of graphene growth on Cu-Ni alloy is by precipitation at the surface from carbon dissolved in the bulk of the alloy foil that diffuses to the surface. The growth parameters were varied to investigate their effect on graphene coverage and isotopic composition. It was found that higher temperature, longer exposure time, higher rate of bulk diffusion for (12)C vs(13)C, and slower cooling rate all produced higher graphene coverage on this type of Cu-Ni alloy foil. The isotopic composition of the graphene layer(s) could also be modified by adjusting the cooling rate. In addition, large-area, AB-stacked bilayer graphene transferrable onto Si/SiO(2) substrates was controllably synthesized.
强耦合双层石墨烯（即 AB 堆垛）在商业“90-10”Cu-Ni 合金箔上生长得特别好。然而，双层石墨烯在 Cu-Ni 合金箔上生长的机制尚未被发现。碳同位素标记（（12）CH（4）和（13）CH（4）的顺序剂量）和拉曼光谱映射被用于研究生长过程。研究发现，石墨烯在 Cu-Ni 合金上的生长机制是通过从合金箔体相溶解的碳在表面沉淀而生长，这些碳扩散到表面。改变生长参数以研究它们对石墨烯覆盖率和同位素组成的影响。结果发现，较高的温度、较长的暴露时间、（12）C 相对于（13）C 的体相扩散率较高以及较慢的冷却速率都在这种类型的 Cu-Ni 合金箔上产生了更高的石墨烯覆盖率。通过调整冷却速率，也可以对石墨烯层的同位素组成进行修饰。此外，还可控合成了大面积、可转移到 Si/SiO（2）衬底上的 AB 堆叠双层石墨烯。
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