Preparation and Raman spectroscopy of low-angle twisted trilayer graphene

Graphene is the most studied material in the world in recent years, from two dimensions to three dimensions, through Bernal stack to multilayer, and finally into graphite, we can see obvious dimensional changes. Therefore, the interaction between layers is very important, and one of them, twisted graphene, which is different from natural ordered stack, has also appeared. If the rotation angle is regarded as a new degree of freedom, angle related properties can be introduced into graphene, and a series of new physical phenomena have become a new research interest. This article shows a transfer glass slide for picking up two-dimensional materials, which can effectively pick up hBN, graphene, etc. The low-angle twisted (1+2) trilayer graphene and hexagonal boron-nitride heterojunction was made by tear-rotate-pick, and their stacking rules were observed by Raman spectroscopy. We found that after covering a certain thickness of hBN, the Raman characteristic peak intensity of the trilayer graphene has a certain attenuation, and has a great impact on the G peak, while the G peak and 2D peak positions have a shift of 2 cm^-1 and 5 cm^-1 respectively. The Raman spectrum of the low-angle twisted trilayer graphene prepared by us also shows a different characteristic peak pattern from that of the common ABA and ABC stacked trilayer graphene. Among them, the G peak of the 0.1° sample becomes flat, and the 2D peak appears an obvious inflection point. While the 0.5° sample is similar to the ABA stacked trilayer graphene, but the 2D peak is more gentle.