Review of fabrication methods, physical properties, and applications of twisted bilayer graphene

Abstract

Graphene is a novel quasi-two-dimensional honeycomb nanomaterial. It exhibits excellent properties and modification options, and the layer-number and configuration of graphene have an important influence on its performance. The quantum state of a quasi-particle in a solid is determined by its own symmetrical nature. The twisted bilayer graphene breaks the symmetry and produces a long-period Moiré pattern due to the slight misalignment between the honeycomb lattices of each layer, which leads to a strong coupling between the layers, and thus changing some physical properties of graphene such as electronic energy band, phonon dispersion, and energy barrier and presents unique performance. For example, the superconductor phase transition can be excited by the gate voltage. The band gap can be continuously controlled in a range of 0-250 meV, and the responsiveness of the photoelectric effect is 80 times higher than that of the single-layer graphene. Therefore, it is of great significance to study the functionalization of twisted bilayer graphene. At the same time, the theoretical and experimental research progress of the transformation of the twisted bilayer layered graphene into the diamond-like carbon is also discussed, which presents the structure and performance of diamond-like carbon. It is found that hydrogenated twisted bilayer graphene bonds between layers and forms sp<sup>3</sup> hybrid bonds, which transforms into a diamond-like structure. The number and distribution of sp<sup>3</sup> hybrid bonds have an important influence on its performance. The twist angle of twisted bilayer graphene affects its phase transition structure and energy barrier. The effect of the twist angle of the twisted bilayer graphene on its intrinsic properties is further evaluated and reveals the behavioral characteristics of this novel nanomaterial. The unique properties of twisted bilayer graphene give rise to a wide range of applications. It is the key to the application of twisted bilayer graphene with a large area, high quality and controlled twist angle. The mechanical exfoliation method can prepare angle-controlled twisted bilayer graphene, but there are problems such as low efficiency and inability to prepare large-area twisted bilayer graphene. The large-area twisted bilayer graphene can be prepared directly by epitaxial growth and chemical vapor deposition methods, but the twist angle cannot be precisely controlled.<br/>Finally, we mention how to control the preparation of twisted bilayer graphene, analyze its regulation mechanism, and discuss the shortcomings and development trends of those processes. Therefore, in this paper, the three aspects of the transport properties, crystal structure transformation and preparation of twisted bilayer graphene are expounded, and its potential application in the field of advanced electronic devices is also prospected.