Twinning and Twisting of Tri- and Bilayer Graphene

Abstract

The electronic, optical, and mechanical properties of bilayer and trilayer graphene vary with their structure, including the stacking order and relative twist, providing novel ways to realize useful characteristics not available to single layer graphene. However, developing controlled growth of bilayer and trilayer graphene requires efficient large-scale characterization of multilayer graphene structures. Here, we use dark-field transmission electron microscopy for rapid and accurate determination of key structural parameters (twist angle, stacking order, and interlayer spacing) of few-layer CVD graphene. We image the long-range atomic registry for oriented bilayer and trilayer graphene, find that it conforms exclusively to either Bernal or rhombohedral stacking, and determine their relative abundances. In contrast, our data on twisted multilayers suggest the absence of such long-range atomic registry. The atomic registry and its absence are consistent with the two different strain-induced deformations we observe; by tilting the samples to break mirror symmetry, we find a high density of twinned domains in oriented multilayer graphene, where multiple domains of two different stacking configurations coexist, connected by discrete twin boundaries. In contrast, individual layers in twisted regions continuously stretch and shear independently, forming elaborate Moiré patterns. These results, and the twist angle distribution in our CVD graphene, can be understood in terms of an angle-dependent interlayer potential model.

In-plane chiral tunneling and out-of-plane valley-polarized quantum tunneling in twisted graphene trilayer

“…The stacking misorientation of the third layer leads to the appearance of Moiré patterns in the structure, which have been observed in recent experiments [26][27][28][29]. More importantly, the rotation of the third layer separates the Dirac cones of the twisted monolayer, K S (or K' S ), and the parabolic bands of the Bernal bilayer, K B (or K' B ), in the reciprocal space, as shown in Fig.…”

A facile method for the selective decoration of graphene defects based on a galvanic displacement reaction

“…Because of the self-limiting growth of graphene on Cu by CVD, the formation of multilayers is not clearly understood. After the analysis of the stacking configuration of the multiple layers using HR-TEM, 32 several hypotheses, such as an adsorption-diffusion mechanism and a penetration mechanism of the carbon sources, have been proposed. 33,34 However, few options exist for determining the configuration except HR-TEM, which requires a complicated sample preparation process and expensive tools.…”

Many‐body effects in optical response of graphene‐based structures

“…[37,40] Twisted graphene bilayers A mutual rotation of graphene layers can result in various stacking configurations, which are not common in natural graphite, and such structures can be realized in CVD conditions of a graphene growth. [75] A superposition of the two rotated honeycomb lattices is observed as a Moire pattern in scanning tunneling microscopy images. [76] Geometry of twisted graphene bilayer can be characterized by a combination of a relative rotation angle varied from 08 to 308 and a lateral translation between the layers.…”