化学气相沉积法在液态金属上快速生长石墨烯单晶（英文）

Insight into the rapid growth of graphene single crystals on liquid metal via chemical vapor deposition

实现石墨烯大单晶的快速生长对于其未来在光电及电学器件领域的应用十分必要.目前已报道的在多晶金属衬底上生长石墨烯单晶的工作通常是通过降低前驱体供应量从而抑制成核来实现的,而这会显著降低成核以及后续生长的速度.新兴的液态金属催化剂具有准原子级平滑的表面和高扩散速率.理论上,液态金属是一个天然理想的基底,可同时实现低密度成核和快速生长.但截至目前,尚无工作探讨液态金属上石墨烯单晶的快速生长.在本研究中,我们成功地在液态铜表面实现了毫米级高质量石墨烯单晶的生长.液态铜中丰富的自由电子能加速石墨烯的成核,且其各向同性的平滑表面能显著抑制成核,使得成核密度较低.更重要的是,由于液态铜优异的可流动性,前驱体碳原子能实现快速扩散,这极大促进了石墨烯的生长,最高速率可达79μm s^-1.我们希望这一关于液态铜体系中石墨烯生长速率的研究能丰富研究者们对液态金属上二维材料生长行为的认知.我们也相信利用液态金属来实现石墨烯快速生长的策略能被拓展至其他二维材料,由此来促进它们在未来光电以及电学器件领域的应用.

Previous reports about the growth of large graphene single crystals on polycrystalline metal substrates usually adopted the strategy of suppressing the nucleation by lowering the concentration of the feedstock, which greatly limited the rate of the nucleation and the sequent growth. The emerging liquid metal catalyst possesses the characteristic of quasi-atomically smooth surface with high diffusion rate. In principle, it should be a naturally ideal platform for the lowdensity nucleation and the fast growth of graphene. However,the rapid growth of large graphene single crystals on liquid metals has not received the due attention. In this paper, we firstly purposed the insight into the rapid growth of large graphene single crystals on liquid metals. We obtained the millimeter-size graphene single crystals on liquid Cu. The rich free-electrons in liquid Cu accelerate the nucleation, and the isotropic smooth surface greatly suppresses the nucleation.Moreover, the fast mass-transfer of carbon atoms due to the excellent fluidity of liquid Cu promotes the fast growth with a rate up to 79 μm s^-1. We hope the research on the growth speed of graphene on liquid Cu can enrich the recognition of the growth behavior of two-dimensional(2 D) materials on the liquid metal. We also believe that the liquid metal strategy for the rapid growth of graphene can be extended to various 2 D materials and thus promote their future applications in the photonics and electronics.