Nano-scale analysis of graphene layers by tip-enhanced near-field Raman spectroscopy
Nano-scale analysis of graphene layers by tip-enhanced near-field Raman spectroscopy
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DOI：
10.1002/jrs.2366
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发表时间：
2009-10-01
影响因子：
2.5
通讯作者：
Kawata, Satoshi
中科院分区：
文献类型：
--
作者：
Saito, Yuika;Verma, Prabhat;Kawata, Satoshi
我们利用尖端增强近场拉曼光谱(TERS)对石墨烯薄膜进行了纳米尺度的光学分析。在该技术中，近场探头作为纳米光源实现了接近30 nm的空间分辨率。根据近场探测产生的硅拉曼能带的强度变化，我们可以方便地估计边缘边界和堆积层的数量。层数测量揭示了材料的纳米尺度性质，以及局部缺陷和边缘边界的存在。G带的强度变化表现为沿层边界的阶梯状行为，而2D峰的两个成分甚至在层内也表现出更复杂的行为。2D波段的峰值起伏也反映了层间相互作用引起的局部应力分布。通过G带的峰位置和宽度之间的关联，观察到了超额电荷效应，揭示了它们在层内的纳米尺度分布。除了振动分析，我们还在同一个实验平台上成功地估计了二维成像中的层数，这使得我们能够高通量地无损地识别石墨烯层，这对这种材料的评估至关重要，特别是在未来的设备应用中。版权所有(C)2009 John Wiley&Sons，Ltd.
We demonstrate nano-scale optical analysis of graphene layers by tip-enhanced near-field Raman spectroscopy (TERS). In this technique, the spatial resolution similar to 30 nm is realized by the near-field probe which acts as a nano-light source. From the intensity change of the Raman band of silicon generated from the near-field probe, we can conveniently estimate the edge boundaries and the number of stacking layers. TIERS measurement across the layer edges reveals the nano-scale properties of the material as well as the existence of local defects and edge boundaries. The intensity change of the G-band shows the step-like behavior that follows the layer boundary, whereas the two components in 2D peak show more complex behaviors even inside layers. The peak fluctuation in the 2D band also suggests the local stress distribution due to interlayer interactions. An excess charge effect is observed through the correlation between the peak position and the width of the G-band and their nano-scale distribution within a layer is revealed. Besides the vibrational analysis, we successfully performed the estimation of the number of layers in two-dimensional imaging by the same experimental platform, which allows us high-throughput nondestructive identification of graphene layers critical for the evaluation of this material especially in future device applications. Copyright (C) 2009 John Wiley & Sons, Ltd.