化学气相沉积是目前最重要的一种制备高质量、大面积石墨烯的方法.而铜是化学气相沉积法制备石墨烯中最常用的生长基底.虽然有大量文章报道了关于石墨烯的生长条件及生长机理,但是作为最广泛采用的材料,铜基底上双层及多层石墨烯的生长机理仍然在探索中.本文采用常压化学气相沉积法,以乙醇为碳源在铜基底上生长石墨烯,并将其转移到SiO2/Si基底上.用场发射扫描电镜、透射电镜、拉曼光谱、光学显微镜对所制备的石墨烯进行表征和层数分析,对转移到不同基底上的不同层数的石墨烯进行了透光性分析.结果表明,常压条件下铜箔表面能够生长出质量较高、连续性较好的双层至多层石墨烯.此外,我们还对铜基底上双层至多层石墨烯的生长机理进行了探讨.%Chemical vapor deposition is widely utilized to synthesize graphene with controlled properties for many applications. And it is one of the most important methods for the preparation of graphene with high quality in large area. Cu substrate is most commonly used for the preparation of graphene in chemical vapor deposition. As is well known, the properties of graphene are greatly affected by the number of layers. However, the syntheses and mechanisms of bi-layer and multi-layer graphene on Cu substrates are still under debate. And how to make a breakthrough in realizing the controllable syntheses of bi-layer and multi-layer graphene on Cu substrates has become a direction for many researchers.In this work, we report bi-layer and multi-layer graphene on Cu substrates prepared by atmospheric pressure chemical vapor deposition. Firstly, the Cu foil is placed on the quartz slides of the tube furnace and heated to 1000 ?C with a rate of 15 ?C/min. After reaching 1000 ?C, the Cu foilis annealed for 2 h in a gas mixture of hydrogen (20 sccm) and argon (380 sccm). After that, the graphene growth is carried out at 1000 ?C under an 80 sccm gas mixture of argon and ethanol. Then, the samples are cooled down to the room temperature with a rate of 100 ?C/min in a protection gas of hydrogen and argon, and then taken out of the furnace. The graphene is prepared on the Cu foils and finally transferred onto the SiO2/Si substrates.The quality and number of layers of the as-produced graphene are assessed by field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, and optical microscopy. By tuning the graphene growth, the monolayer, bi-layer and multi-layer graphene with higer quality and better continuity are obtained. And the growth times of monolayer, bi-layer, and four-layers graphene are respectively 25, 40, and 60 s. And wefind that the graphene layer will be increased in the process of insulation. The growth mechanisms of bi-layer and multi-layer graphene on copper substrates by atmospheric pressure chemical vapor deposition are also discussed. There will be some indiffusible carbon atoms or radicals near the copper foil surface due to the small molecular diffusion mean free path under normal pressure. We suggeste that the bi-layer and multi-layer graphene grown on copper substrates by atmospheric pressure chemical vapor deposition is dominated by van der Waals epitaxial mechanism. This work provides a reference for improving the quality of chemical vapor deposition monolayer, bi-layer and multi-layer graphene.
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