Szirmai Péter, Márkus Bence G, Chacón-Torres Julio C, Eckerlein Philipp, Edelthalhammer Konstantin, Englert Jan M, Mundloch Udo, Hirsch Andreas, Hauke Frank, Náfrádi Bálint, Forró László, Kramberger Christian, Pichler Thomas, Simon Ferenc
Faculty of Physics, University of Vienna, Strudlhofgasse 4., Vienna, A-1090, Austria.
Department of Physics, Budapest University of Technology and Economics and MTA-BME Lendület Spintronics Research Group (PROSPIN), PO Box 91, H-1521, Budapest, Hungary.
Sci Rep. 2019 Dec 20;9(1):19480. doi: 10.1038/s41598-019-55784-6.
An efficient route to synthesize macroscopic amounts of graphene is highly desired and bulk characterization of such samples, in terms of the number of layers, is equally important. We present a Raman spectroscopy-based method to determine the typical upper limit of the number of graphene layers in chemically exfoliated graphene. We utilize a controlled vapour-phase potassium intercalation technique and identify a lightly doped stage, where the Raman modes of undoped and doped few-layer graphene flakes coexist. The spectra can be unambiguously distinguished from alkali doped graphite, and modeling with the typical upper limit of the layers yields an upper limit of flake thickness of five layers with a significant single-layer graphene content. Complementary statistical AFM measurements on individual few-layer graphene flakes find a consistent distribution of the layer numbers.
人们迫切需要一种高效合成大量石墨烯的方法，并且对这类样品进行层数方面的体相表征同样重要。我们提出了一种基于拉曼光谱的方法来确定化学剥离石墨烯中层数的典型上限。我们利用可控的气相钾插层技术，并识别出一个轻度掺杂阶段，在此阶段未掺杂和掺杂的少层石墨烯薄片的拉曼模式共存。这些光谱可以与碱掺杂石墨明确区分开来，并且用层数的典型上限进行建模得出薄片厚度的上限为五层，其中单层石墨烯含量显著。对单个少层石墨烯薄片进行的补充统计原子力显微镜测量发现层数分布一致。
