Raman imaging of twist angle variations in twisted bilayer graphene at intermediate angles

Abstract

Van der Waals layered materials with well-defined twist angles between the crystal lattices of individual layers have attracted increasing attention due to the emergence of unexpected material properties. As many properties critically depend on the exact twist angle and its spatial homogeneity, there is a need for a fast and non-invasive characterization technique of the local twist angle, to be applied preferably right after stacking. We demonstrate that confocal Raman spectroscopy can be utilized to spatially map the twist angle in stacked bilayer graphene for angles between 6.5° and 8° when using a green excitation laser. The twist angles can directly be extracted from the moiré superlattice-activated Raman scattering process of the transverse acoustic (TA) phonon mode. Furthermore, we show that the width of the TA Raman peak contains valuable information on spatial twist angle variations on length scales below the laser spot size of ~ 500 nm.

14 pages, 10 figures

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Cited by in corpus (10)

• Superconductivity from electronic interactions and spin-orbit enhancement in bilayer and trilayer graphene
• Determining the Twist Angle of Bilayer Graphene by Machine Learning Analysis of its Raman Spectrum
• Probing interlayer interactions and commensurate-incommensurate transition in twisted bilayer graphene through Raman spectroscopy
• High transmission in twisted bilayer graphene with angle disorder
• Charge carrier density-dependent Raman spectra of graphene encapsulated in hexagonal boron nitride
• Band gap formation in commensurate twisted bilayer graphene/hBN moiré lattices
• Mesoscopic Stacking Reconfigurations in Stacked van der Waals Film
• Negative electronic compressibility in charge islands in twisted bilayer graphene
• Gate-tunable Josephson diodes in magic-angle twisted bilayer graphene
• Straintronics and twistronics in bilayer graphene