Gap States at Low-Angle Grain Boundaries in Monolayer Tungsten Diselenide

Huang, Yu Li; Ding, Zijing; Zhang, Wenjing; Chang, Yung‐Huang; Shi, Yumeng; Li, Lain‐Jong; Song, Zhibo; Zheng, Yu; Chi, Dongzhi; Quek, Su Ying; Wee, Andrew T. S.

doi:10.1021/acs.nanolett.6b00888

Cited by 60 publications

(63 citation statements)

References 42 publications

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“…[13,14,25] Moreover, the electronic structure of the GBs were studied using scanning tunneling microscopy (STM). [26,27] Importantly, mirror twin boundaries (MTBs) with particular atomic structures between regions with 60° relative orientation have been repeatedly reported. [28][29][30] These were observed either upon flake merging, inside grains to accommodate for the nonstoichiometry, or produced a posteriori by electron-beam or thermal-annealing treatments.…”

Section: Progress Reportmentioning

confidence: 99%

Engineering the Electronic Properties of Two‐Dimensional Transition Metal Dichalcogenides by Introducing Mirror Twin Boundaries

Komsa

Krasheninnikov

2017

Adv Elect Materials

100

109

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Grain boundaries in 2D materials can have marked influence on the material properties. The effects can be not only detrimental, but also beneficial in transition metal dichalcogenides (TMDs), so that controlling the density and type of the boundaries in these systems should be important for engineering their properties. However, this is often possibly only during the growth stage. Molybdenum and tungsten dichalcogenides feature a particular set of 60° mirror twin boundaries, which are reported to occur upon merging of the growing flakes, to appear during growth to accommodate for the nonstoichiometry of the sample, or to be produced a posteriori by electron irradiation or thermal annealing. Furthermore, different preparation conditions lead to different atomic structure of the boundary, which consequently exhibit different electronic properties. This has obviously garnered interest for the ability to control grain boundary types and densities. In this progress report, the recent experimental and theoretical work related to the characterization of mirror twin boundaries is reviewed. A consistent set of formation energies for the mirror twin boundaries is provided, which then allows a coherent picture on the formation mechanisms under different conditions to be drawn. Finally, the electronic structure of these boundaries is analyzed and their potential applications are discussed.

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Section: Progress Reportmentioning

confidence: 99%

Engineering the Electronic Properties of Two‐Dimensional Transition Metal Dichalcogenides by Introducing Mirror Twin Boundaries

Komsa

Krasheninnikov

2017

Adv Elect Materials

100

109

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“…GB and edges always exhibit PL signals different from that at the crystal center. These nonuniformities can be attributed to localized states, doping, and strain [57,78,119,120]. Figure 10A and B shows PL and Raman images of monolayer MoS 2 after thermal annealing.…”

Section: Edge and Grain Boundary In Tmds Probed By Pl Spectroscopymentioning

confidence: 99%

“…Scanning transmission electron microscope studies on GBs in 2D TMDs have found that a variety of non-6-membered rings (4-, 5-, 7-, and 8-membered rings) together with strained 6-membered rings are present at GBs with different misorientation angles [120]. Density functional theory (DFT) calculation has shown that all these non-6-membered dislocation cores can induce deep gap states [120].…”

Section: Edge and Grain Boundary In Tmds Probed By Pl Spectroscopymentioning

confidence: 99%

Spectroscopic investigation of defects in two-dimensional materials

2017

Nanophotonics

125

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Two-dimensional (2D) materials have been extensively studied in recent years due to their unique properties and great potential for applications. Different types of structural defects could present in 2D materials and have strong influence on their properties. Optical spectroscopic techniques, e.g. Raman and photoluminescence (PL) spectroscopy, have been widely used for defect characterization in 2D materials. In this review, we briefly introduce different types of defects and discuss their effects on the mechanical, electrical, optical, thermal, and magnetic properties of 2D materials. Then, we review the recent progress on Raman and PL spectroscopic investigation of defects in 2D materials, i.e. identifying of the nature of defects and also quantifying the numbers of defects. Finally, we highlight perspectives on defect characterization and engineering in 2D materials.

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“…C60F48 is selected as a model molecule because it is a molecular acceptor [32] with applications in lithium batteries [33,34], electronic devices [35][36][37] and so on [38,39]. WSe2 represents as a prototypical 2D-TMD semiconductor with a high photon quantum yield [30,31,40,41]. As revealed by STM investigations, a liquid-solid surface phase transition is observed from a loose-packed liquid phase at dilute coverage to a closed-packed solid phase at high coverage.…”

Section: Introductionmentioning

confidence: 99%

Liquid-solid surface phase transformation of fluorinated fullerene on monolayer tungsten diselenide

Song

Wang

et al. 2018

Phys. Rev. B

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Hybrid van der Waals (vdW) heterostructures constructed by the integration of organic molecules and two-dimensional (2D) transition metal dichalcogenide (TMD) materials have useful tunable properties for flexible electronic devices. Due to the chemically inert and atomically smooth nature of the TMD surface, well-defined crystalline organic films form atomically sharp interfaces facilitating optimal device performance. Here, the surface phase transformation of the supramolecular packing structure of fluorinated fullerene (C60F48) on single-layer (SL) tungsten diselenide (WSe2) is revealed by low-temperature (LT) scanning tunnelling microscopy (STM), from thermally stable liquid to solid phases as the coverage increases. Statistical analysis of the intermolecular interaction potential reveals that the repulsive dipole-dipole interaction induced by interfacial charge transfer and substrate-mediated interactions play important roles in stabilizing the liquid C60F48 phases. Theoretical calculations further suggest that the dipole moment per C60F48 molecule varies with the surface molecule density, and the liquid-solid transformation could be understood from the perspective of the thermodynamic free energy for open systems. This study offers new insights into the growth behaviour at 2D organic/TMD hybrid heterointerfaces.

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Gap States at Low-Angle Grain Boundaries in Monolayer Tungsten Diselenide

Cited by 60 publications

References 42 publications

Engineering the Electronic Properties of Two‐Dimensional Transition Metal Dichalcogenides by Introducing Mirror Twin Boundaries

Engineering the Electronic Properties of Two‐Dimensional Transition Metal Dichalcogenides by Introducing Mirror Twin Boundaries

Spectroscopic investigation of defects in two-dimensional materials

Liquid-solid surface phase transformation of fluorinated fullerene on monolayer tungsten diselenide

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