Abstract Two-dimensional (2D) materials are intrinsically heterogeneous. Both localized defects, such as vacancies and dopants, and mesoscopic boundaries, such as surfaces and interfaces, give rise to compositional or structural heterogeneities. The presence of defects and boundaries can break lattice symmetry, modify the energy landscape, and create quantum confinement, leading to fascinating electronic properties different from the “ideal” 2D sheets. This review summarizes recent progress in understanding the roles of defects and boundaries in electronic, magnetic, thermoelectric, and transport properties of 2D layered materials. The focus is on the understanding of correlation of atomic-scale structural information with electronic functions by interrogating heterogeneities individually. The materials concerned are graphene, transition metal dichalcogenides (TMDs), hexagonal boron nitride (hBN), and topological insulators (TIs). The experimental investigations benefit from new methodologies and techniques in scanning tunneling microscopy (STM), including spin-polarized STM, scanning tunneling potentiometry (STP), scanning tunneling thermopower microscopy, and multi-probe STM. The experimental effort is complemented by the computational and theoretical approaches, capable of discriminating between closely competing states and achieving the length scales necessary to bridge across features such as local defects and complex heterostructures. The goal is to provide a general view of current understanding and challenges in studying the heterogeneities in 2D materials and to evaluate the potential of controlling and exploiting these heterogeneities for novel functionalities and electron devices.

中文翻译：

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二维材料电子行为中缺陷和边界作用的空间分辨研究

摘要 二维 (2D) 材料本质上是异质的。局部缺陷（例如空位和掺杂剂）和介观边界（例如表面和界面）都会引起成分或结构异质性。缺陷和边界的存在会破坏晶格对称性、改变能量图谱并产生量子限制，从而导致与“理想”二维片材不同的迷人电子特性。本综述总结了在理解缺陷和边界在二维层状材料的电子、磁、热电和传输特性中的作用方面的最新进展。重点是通过单独询问异质性来理解原子尺度结构信息与电子功能的相关性。有关材料是石墨烯，过渡金属二硫属化物 (TMD)、六方氮化硼 (hBN) 和拓扑绝缘体 (TI)。实验研究受益于扫描隧道显微镜 (STM) 的新方法和技术，包括自旋极化 STM、扫描隧道电位 (STP)、扫描隧道热电显微镜和多探针 STM。实验工作得到了计算和理论方法的补充，能够区分密切竞争的状态并实现跨越局部缺陷和复杂异质结构等特征所需的长度尺度。