Spatially-resolved studies on the role of defects and boundaries in electronic behavior of 2D materials. Issue 3 (August 2017)

• Record Type: Journal Article
• Authors: Hus, Saban M.; Li, An-Ping
• Is Part Of: Progress in surface science. Volume 92:Issue 3(2017)
• Page Start: 176
• Page End: 201
• Publication Date: 2017-08
• Subjects: 0D zero-dimensional -- 1D one dimensional -- 2D two-dimensional -- 3D three-dimensional -- AFM atomic force microscope -- BL bilayer -- CVD chemical vapor deposition -- DFT density functional theory -- dI/dV differential tunneling conductance -- DOS density of states -- EBID electron beam induced deposition -- ED dirac point -- EF Fermi energy -- GB grain boundary -- hBN hexagonal boron nitride -- LEEM low-energy electron microscopy -- MIM microwave impedance microscopy -- ML monolayer -- QHE quantum hall effect -- SEM scanning electron microscope -- SPM scanning probe microscopy -- SQUID Superconducting Quantum Interference Device -- STM scanning tunneling microscopy -- STP scanning tunneling potentiometry -- STS scanning tunneling spectroscopy -- TI topological insulator -- TL trilayer -- TMD transition metal dichalcogenides -- TSS topological surface states -- UHV ultra-high vacuum -- VBM valance band maximum -- vdW van der Waals -- Vth thermoelectric voltage -- XPS X-ray photoelectron spectroscopy -- µ-LEED micro low-energy electron diffraction; Scanning tunneling microscopy -- Low-dimensional materials -- Monolayer -- Defects -- Interfaces -- Grain boundaries -- Heterostructures -- Electronic structures -- Electrical transport -- Magnetism -- Thermoelectrics; Surface chemistry -- Periodicals; Surfaces (Technology) -- Periodicals; Surface Properties -- Periodicals; Chimie des surfaces -- Périodiques; Surfaces (Technologie) -- Périodiques; 541.33
• DOI: 10.1016/j.progsurf.2017.07.001
• Languages: English
• ISSNs: 0079-6816

Abstract

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.