研究目的
Investigating the equi-biaxial compressive strain in monolayer graphene on SiO2 and Si3N4 substrates induced by thermal cycling in vacuum, and understanding its impact on the morphology and properties of graphene.
研究成果
The study successfully introduced equi-biaxial compressive strain in monolayer graphene via thermal cycling, leading to the formation of buckling ridges that follow the symmetry of graphene's crystal structure. The biaxial Grüneisen parameter was reliably measured, and the buckling ridges were found to be similar to those in synthesized graphene, suggesting a common formation mechanism. The method provides a robust way to study graphene-substrate interactions and strain effects on graphene properties.
研究不足
The study is limited to monolayer graphene on SiO2 and Si3N4 substrates. The thermal cycling method may not be directly applicable to other substrates or multilayer graphene. The linear approximation of strain evolution may not capture all nonlinear effects.
1：Experimental Design and Method Selection:
Monolayer graphene flakes were prepared by mechanical exfoliation on SiO2/Si and Si3N4/Si substrates. The samples were subjected to thermal cycling in vacuum, with heating temperatures varied to induce strain. Raman spectroscopy and AFM were used to characterize the strain and morphology changes.
2：Sample Selection and Data Sources:
Monolayer graphene flakes with dimensions of tens of micrometers were used. The substrates were SiO2/Si (300 nm SiO2) and Si3N4/Si (300 nm Si3N4).
3：4).
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: AFM (Park System XE-100), Raman spectroscopy (HORIBA LabRAM HR800), vacuum chamber (10-8 Torr base pressure).
4：Experimental Procedures and Operational Workflow:
Graphene samples were heated to various temperatures in vacuum and then cooled back to room temperature. After each cycle, Raman spectroscopy and AFM were performed to measure strain and observe buckling ridges.
5：Data Analysis Methods:
Raman peak shifts were analyzed to determine strain. AFM images were analyzed to observe buckling ridges and measure subtended angles between ridges.
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