研究目的
Investigating the formation of highly-oriented wrinkles in chemical vapour deposition grown graphene and their potential to open a bandgap in otherwise zero-bandgap graphene films.
研究成果
The study demonstrates that a region of graphene with a controllable bandgap similar to a narrow gap semiconductor can be regularly formed using lithographic techniques. The strain present along the ripple is of the biaxial type, leading to a bandgap opening of up to 0.4 eV. This shows great promise for being exploited as a basis for fabrication of graphene electronic devices.
研究不足
The technical and application constraints include the difficulty in deconvolving the separate contributions of different layers due to the wrinkle being formed from only a portion of the graphene present. The spatial resolution limitations may affect the ability to determine the extent of both types of strain accurately.
1：Experimental Design and Method Selection:
Combined atomic force microscopy and Raman spectroscopy study of wrinkle formation in chemical vapour deposition graphene. Graphene was grown on copper and repeatedly transferred onto a SiO2 substrate to form a four-layer graphene stack. Two electrodes with a small gap of 1μm were deposited on top of graphene to generate a long wrinkle along the channel.
2：Sample Selection and Data Sources:
Graphene samples grown on copper and transferred onto SiO2 substrates. AFM images and Raman spectra were recorded of the graphene regions between the electrodes.
3：List of Experimental Equipment and Materials:
Atomic force microscopy (AFM) for morphology imaging, Raman spectroscopy for optical properties analysis, and density functional theory (DFT) package CASTEP for electronic structure calculations.
4：Experimental Procedures and Operational Workflow:
AFM images were recorded to analyze the morphology of graphene layers and their dependence on the size of the separation between the electrodes. Polarized Raman measurements were performed to determine the type and amount of strain present along the wrinkle.
5：Data Analysis Methods:
The amount of strain was estimated using AFM, polarized Raman, and DFT modelling. The strain's effect on the local bandstructure was analyzed through atomistic modelling.
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