论文标题
用拉曼光谱探测的石墨烯 - 波波界面处的电子耦合变化
Varying Electronic Coupling at Graphene-Copper Interfaces Probed with Raman Spectroscopy
论文作者
论文摘要
由于铜上石墨烯的合成成为基础研究和工业应用的主要制备方法之一，因此需要对石墨烯/CU系统的拉曼光谱进行定量了解，以了解其相互作用如何影响石墨烯的电子结构。使用多波长拉曼光谱法，我们研究了在Cu箔和Cu膜和Cu膜/SIO2上生长的石墨烯的三种类型的石墨烯，以及Cu蒸发的去角质脱落的石墨烯。前两个样品的2D峰频率即使考虑菌株的效果，对于1.96 eV激发的预期频率约为17 cm-1。更值得注意的是，随着激发能量的增加，2D的升级减少。基于使用Cu蒸发的石墨烯的控制实验，我们揭示了光谱异常是由环境依赖性的非线性分散剂在石墨烯的电子带中诱导的，并确定了电子修饰的程度。我们还表明，源自CU的差分热膨胀的G和2D峰的大型上缩合可以通过靠背膜具有无微不足道的热膨胀的介电底物来显着降低。在本研究中提出的石墨烯和CU之间的电子耦合的定量分析将在表征生长的石墨烯以及其他形式的表征方面非常有用。
As the synthesis of graphene on copper became one of the primary preparation methods for both fundamental research and industrial application, Raman spectra of graphene/Cu systems need to be quantitatively understood regarding how their interactions affect the electronic structure of graphene. Using multi-wavelength Raman spectroscopy, we investigated three types of graphene bound on Cu: graphene grown on Cu foils and Cu film/SiO2, and Cu-evaporated exfoliated graphene. 2D peak frequencies of the first two samples were ~17 cm-1 higher than expected for 1.96 eV excitation even when the effect of strain was considered. More notably, the upshift in 2D decreased with increasing excitation energy. Based on control experiments using Cu-evaporated graphene, we revealed that the spectral anomaly was induced by environment-dependent nonlinear dispersion in the electronic bands of graphene and determined the degree of the electronic modification. We also showed that the large upshifts of G and 2D peaks originating from differential thermal expansion of Cu could be significantly reduced by backing Cu films with dielectric substrates of insignificant thermal expansion. The quantitative analysis of electronic coupling between graphene and Cu presented in this study will be highly useful in characterizing as-grown graphene and possibly in other forms.
