单层石墨烯表面上芳香类吸附分子局域掺杂行为的超分辨拉曼光谱研究

Tailoring of graphene's electronic properties by aromatic molecules brings many hot research topics in recent years. Aromatic molecules act not only as dopants for graphene, but also as contaminations degrading electric performance of graphene devices. In future manufacturing of graphene nano devices, local doping characteristics of adsorbed molecules are expected to be substantial to design and degradation of devices. In this proposal, super-spatial tip enhanced Raman spectroscopy(TERS) is proposed to detect graphene's Raman singal modified by interactions among aromatic molecules, graphene and metallic tip. Electronic parameters， such as carrier density, band strucutre, etc, of graphene adsorbed by different molecules can be calculated from Raman signals enhanced simultaneously by metallic tip and graphene(TERS+GERS). Spatially doping inhomogenity distribution of small aromatic molecules can be finally obtianed by nanocale spatially resolved TERS imaging. Spatial distribution of local doping parameters, such as doping type, fermi level, carrier density variation, etc, for edges，wrinkles, and also the aromatic-ester molecules on surface can also be obtianed. Super spatially optical detection of doping and contamination on future graphene nano devices are proposed to be key topics in this proposal. The results of this proposal are expected to be helpful for the detection of local doping and contamination in future graphene devices both in theory and in technique.

芳香类分子既能够对石墨烯进行掺杂改性，又有可能作为吸附污染源而导致石墨烯器件性能退化，是近年来的研究热点。在未来石墨烯纳米器件生产中，芳香类吸附分子的局域掺杂行为对器件设计和性能退化有重要意义。在本研究中，申请人计划使用超分辨针尖增强拉曼光谱（TERS），同时利用TERS和石墨烯增强拉曼光谱（GERS），通过对芳香类有机分子-石墨烯-金属针尖相互作用而导致的石墨烯特征拉曼峰的信号变化进行研究，得出不同吸附分子对石墨烯载流子浓度、能带结构等电学参数的影响。通过纳米级空间分辨TERS成像扫描，最终得到芳香类小分子掺杂均匀性分布信息，另外得到石墨烯边缘、褶皱以及表面吸附的芳香酯类大分子等特征缺陷附近纳米尺度内电学特征，如掺杂类型、费米能级和载流子浓度及其空间分布特征。本研究针对未来石墨烯纳米器件的掺杂和污染的超分辨光谱检测中关键问题进行研究，能够为器件局域掺杂和污染的检测提供理论指导和技术支持。

在该项研究中，我们使用新技术制备的TERS探针，对单层石墨烯表面的原生缺陷和PEDOT：PSS芳香分子的掺杂效应等进行了针尖增强拉曼的研究工作，获得了G峰对比度为8.5的增强效应，并对石墨烯表面的缺陷和分子分布进行了高分辨拉曼成像，获得了20nm的纳米级分辨率。另外，高分辨针尖增强拉曼的研究发现，PEDOT分子在zigzag型边缘和缺陷部分更容易偏聚，掺杂效应也更明显。另外，我们使用针尖增强拉曼和针尖增强荧光技术，对类石墨烯材料——单层二硫化钼表面的有机吸附物和表面缺陷进行了研究。该项目瞄准二维材料研究中的前沿问题，开展了特色鲜明的研究工作，在国际top期刊上发表多篇高水平论文。研究结果，针尖增强拉曼技术在二维材料的表征中有着广阔的应用前景。