研究目的
Investigating the effects of twist angles on the Raman spectroscopy characteristics of folded tetralayer graphenes prepared by atomic force microscope.
研究成果
The study demonstrated that the position, width, and intensity of 2D and G peaks of folded tetralayer graphene depend sensitively on the twist angles. A critical twist angle was identified where the 2D peak could be fitted by three Lorentzian peaks. The method of using an AFM probe to fabricate twisted graphene has advantages but requires further development to control the twist angle precisely.
研究不足
The main challenge remaining is how to fabricate folded graphene with a well-defined twist angle. The folding of graphene using AFM is sensitive to the van der Waals force between graphene and the substrate, which cannot be controlled. The direction of the rupture of graphene cannot be controlled during the folding process.
1：Experimental Design and Method Selection:
The study involved the preparation of folded tetralayer graphenes by applying a modulated force to the edge of a bilayer graphene using an AFM. The twist angles between the two bilayer graphenes were measured and their effects on Raman spectra were analyzed.
2：Sample Selection and Data Sources:
Graphene layers were prepared by mechanical exfoliation of graphite and deposited on a SiO2/Si substrate. The layer number was confirmed by optical microscope and Raman spectra.
3：List of Experimental Equipment and Materials:
AFM (Bruker, Multimode 8-HR), micro-Raman spectroscope (Renishaw inVia Raman Spectroscope), RTESPA probe (k = 40 N/m, f0 = 300 kHz).
4：Experimental Procedures and Operational Workflow:
The folding process was operated in contact mode with the AFM probe. Raman measurements were carried out under ambient conditions with laser wavelengths of 514 nm, 532 nm, and 633 nm.
5：Data Analysis Methods:
The position, width, and intensity of 2D and G peaks were analyzed. The 2D peak was fitted by Lorentzian peaks to study the twist angle dependence.
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