Li Qiongyu, Liu Tongzhi, Li You, Li Fang, Zhao Yanshuai, Huang Shihao
School of Electronic, Electrical Engineering and Physics, Fujian University of Technology, Fuzhou 350118, China.
MIIT Key Laboratory of Semiconductor Microstructure and Quantum Sensing, Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094, China.
Nanomaterials (Basel). 2023 Jul 12;13(14):2059. doi: 10.3390/nano13142059.
Bilayer graphene is a contender of interest for functional electronic applications because of its variable band gap due to interlayer interactions. Graphene growth on Cu is self-limiting, thus despite the fact that chemical vapor deposition (CVD) has made substantial strides in the production of monolayer and single-crystal graphene on Cu substrates, the direct synthesizing of high-quality, large-area bilayer graphene remains an enormous challenge. In order to tackle this issue, we present a simple technique using typical CVD graphene growth followed by a repetitive wrinkling-etching-regrowth procedure. The key element of our approach is the rapid cooling process that causes high-density wrinkles to form in the monolayer area rather than the bilayer area. Next, wrinkled sites are selectively etched with hydrogen, exposing a significant portion of the active Cu surface, and leaving the remaining bilayer areas, which enhance the nucleation and growth of the second graphene layer. A fully covered graphene with 78 ± 2.8% bilayer coverage and a bilayer transmittance of 95.6% at room temperature can be achieved by modifying the process settings. Bilayer graphene samples are examined using optical microscopy (OM), scanning electron microscopy (SEM), Raman spectroscopy, and an atomic force microscope (AFM) during this process. The outcomes of our research are beneficial in clarifying the growth processes and future commercial applications of bilayer graphene.
由于层间相互作用导致的可变带隙，双层石墨烯是功能性电子应用中备受关注的候选材料。在铜上生长石墨烯是自限性的，因此尽管化学气相沉积（CVD）在铜衬底上生产单层和单晶石墨烯方面取得了重大进展，但直接合成高质量、大面积的双层石墨烯仍然是一个巨大的挑战。为了解决这个问题，我们提出了一种简单的技术，即采用典型的CVD石墨烯生长方法，然后进行重复的褶皱-蚀刻-再生长过程。我们方法的关键要素是快速冷却过程，该过程会在单层区域而非双层区域形成高密度的褶皱。接下来，用氢气选择性地蚀刻有褶皱的部位，暴露出大部分活性铜表面，而保留其余的双层区域，这增强了第二层石墨烯的成核和生长。通过调整工艺设置，可以实现室温下双层覆盖率为78±2.8%且双层透过率为95.6%的完全覆盖的石墨烯。在此过程中，使用光学显微镜（OM）、扫描电子显微镜（SEM）、拉曼光谱和原子力显微镜（AFM）对双层石墨烯样品进行了检测。我们的研究结果有助于阐明双层石墨烯的生长过程及其未来的商业应用。
