Center for Advanced Materials, University of Houston, Houston, TX 77204, USA.
Nanotechnology. 2012 Jan 27;23(3):035603. doi: 10.1088/0957-4484/23/3/035603. Epub 2011 Dec 16.
Large-scale and transferable graphene films grown on metal substrates by chemical vapor deposition (CVD) still hold great promise for future nanotechnology. To realize the promise, one of the key issues is to further improve the quality of graphene, e.g., uniform thickness, large grain size, and low defects. Here we grow graphene films on Cu foils by CVD at ambient pressure, and study the graphene nucleation and growth processes under different concentrations of carbon precursor. On the basis of the results, we develop a two-step ambient pressure CVD process to synthesize continuous single-layer graphene films with large grain size (up to hundreds of square micrometers). Scanning electron microscopy and Raman spectroscopy characterizations confirm the film thickness and uniformity. The transferred graphene films on cover glass slips show high electrical conductivity and high optical transmittance that make them suitable as transparent conductive electrodes. The growth mechanism of CVD graphene on Cu is also discussed, and a growth model has been proposed. Our results provide important guidance toward the synthesis of high quality uniform graphene films, and could offer a great driving force for graphene based applications.
通过化学气相沉积（CVD）在金属衬底上生长的大面积、可转移的石墨烯薄膜仍然为未来的纳米技术提供了巨大的前景。为了实现这一承诺，关键问题之一是进一步提高石墨烯的质量，例如均匀的厚度、大晶粒尺寸和低缺陷。在这里，我们在常压下通过 CVD 在 Cu 箔上生长石墨烯薄膜，并研究了在不同浓度的碳前体下石墨烯成核和生长的过程。在此基础上，我们开发了一种两步常压 CVD 工艺，以合成具有大晶粒尺寸（高达数百平方微米）的连续单层石墨烯薄膜。扫描电子显微镜和拉曼光谱表征证实了薄膜的厚度和均匀性。转移到载玻片上的石墨烯薄膜具有高导电性和高透光率，适合用作透明导电电极。还讨论了 CVD 石墨烯在 Cu 上的生长机制，并提出了一种生长模型。我们的研究结果为高质量均匀石墨烯薄膜的合成提供了重要指导，并为基于石墨烯的应用提供了巨大的推动力。
