Quasi-Freestanding Monolayer Heterostructure of Graphene and Hexagonal Boron Nitride on Ir(111) with a Zigzag Boundary

Liu, Mengxi; Li, Yuanchang; Chen, Pengcheng; Sun, Jingyu; Ma, Donglin; Li, Qiucheng; Gao, Teng; Gao, Yabo; Cheng, Zhihai; Qiu, Xiaohui; Fang, Ying; Zhang, Yanfeng; Liu, Zhongfan

doi:10.1021/nl502780u

Cited by 121 publications

(155 citation statements)

References 48 publications

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“…The shape of the dI/dV curve has also changed substantially from an asymmetric Vshape to a flatter, more parabolic, shape. Interestingly, our observations are very similar to results obtained by Liu et al [19] for graphene sheets on a hexagonal boron nitride layer. In any case the reconstructed germanene zigzag edges do not exhibit a pronounced metallic edge state.…”

supporting

confidence: 92%

Two-dimensional Dirac signature of germanene

Zhang

Bampoulis

Houselt

2015

Applied Physics Letters

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The structural and electronic properties of germanene coated Ge2Pt clusters have been determined by scanning tunneling microscopy and spectroscopy at room temperature. The interior of the germanene sheet exhibits a buckled honeycomb structure with a lattice constant of 4.3 Å and a buckling of 0.2 Å. The zigzag edges of germanene are reconstructed and display a 4 periodicity. The differential conductivity of the interior of the germanene sheet has a V-shape, which is reminiscent of the density of states of a two-dimensional Dirac system. The minimum of the differential conductivity is located close to the Fermi level and has a non-zero value, which we ascribe to the metallic character of the underlying Ge2Pt substrate. Near the reconstructed germanene zigzag edges the shape of the differential conductivity changes from a V-shape to a more parabolic-like shape, revealing that the reconstructed germanene zigzag edges do not exhibit a pronounced metallic edge state. 2In the past decade a new class of materials has been developed, which is not threedimensional (3D), but two-dimensional (2D) in nature. Graphene is by far the most famous example of this new class of 2D materials [1,2]. Graphene consists of a single layer of sp 2 hybridized carbon atoms that are arranged in a planar honeycomb registry. Graphene is a very appealing material because of its unique physical properties [1,2]. The charge carriers in graphene behave as relativistic massless particles that are described by the Dirac equation, i.e. the relativistic variant of the Schrödinger equation. In the vicinity of the Dirac point the dispersion relation is linear, i.e., where F v is the Fermi velocity,  the reduced Planck constant and k the wave vector. Graphene is a semimetal and the density of states scales linearly with energy. One of the interesting properties of finite graphene sheets is the existence of electronic states that are localized at the edges of graphene. Theory predicts that a zigzag terminated graphene edge is metallic, whereas an armchair terminated graphene edge is semiconducting [3][4][5]. Scanning tunneling microscopy and spectroscopy studies of zigzag and armchair monatomic step edges of graphite have indeed confirmed these theoretical predictions [6][7][8].Since the rise of graphene there has been a growing interest in other two-dimensional materials that exhibit 'graphene'-like properties. The most obvious alternatives for graphene are the group IV elements, i.e. silicon, germanium and tin. Unfortunately, these graphene analogues of silicon (silicene), germanium (germanene) and tin (stanene) do not occur in nature and therefore these materials have to be synthesized. Germanene is one of the youngest members of the graphene family and has not been studied extensively. In contrast to the planar graphene lattice, the germanene honeycomb lattice is buckled. Theoretical calculations have shown that despite this buckling the 2D Dirac properties of germanene are preserved [9] [13]. In particular the work of Dávila et al. [12] provides a...

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supporting

confidence: 92%

Two-dimensional Dirac signature of germanene

Zhang

Bampoulis

Houselt

2015

Applied Physics Letters

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“…In general, there are two major edge types for graphene and MoS 2 : Zigzag and armchair. Since previous theoretical and experimental studies have shown that zigzag (ZZ) edges possess a lower formation energy and are more stable than armchair edges for both graphene 37,38 and MoS 2 39,40 in the growth, here only the zigzag-oriented interfaces are considered, which are named as ZZ interface, as shown in …”

Section: In-plane Interfacial Binding Between Mos 2 and Graphenementioning

confidence: 99%

MoS2-graphene in-plane contact for high interfacial thermal conduction

et al. 2017

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Recent studies showed that the in-plane and inter-plane thermal conductivities of twodimensional (2D) MoS 2 are low, posing a significant challenge in heat management in MoS 2 -based electronic devices. To address this challenge, we design the interfaces between MoS 2 and graphene by fully utilizing graphene, a 2D material with an ultra-high thermal conduction. We first perform ab initio atomistic simulations to understand the bonding nature and structure stability of the interfaces. Our results show that the designed interfaces, which are found to be connected together by strong covalent bonds between Mo and C atoms, are energetically stable.We then perform molecular dynamics simulations to investigate the interfacial thermal conductance. It is found surprisingly that the interface thermal conductance is high, comparable to that of graphene-metal covalent-bonded interfaces. Importantly, each interfacial Mo-C bond serves as an independent thermal channel, enabling the modulation of interfacial thermal conductance by controlling Mo vacancy concentration at the interface. The present work provides a viable route for heat management in MoS 2 based electronic devices.2

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“…26 Similarly, the interface of graphene/h-BN monolayer heterostructures 35 can also induce the mid gaps on the semiconductor part near the interface. These localized mid-gap states, which result from typical of defects in semiconductors, are important because they can affect the optical and transport properties of the material.…”

Section: Electronic Propertiesmentioning

confidence: 99%

Structural, mechanical and electronic properties of in-plane 1T/2H phase interface of MoS2 heterostructures

et al. 2015

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Two-dimensional (2D) molybdenum disulfide (MoS2) phase hybrid system composed by 2H and 1T phase is a natural metal/semiconductor heterostructures and promised a wide range of potential applications. Here, we report the first principle investigations on the structural, mechanical and electronic properties of hybrid system with armchair (AC) and zigzag (ZZ) interfaces. The ZZ type 1T/2H interface are more energy favorable than AC type interface with 3.39 eV/nm. Similar with that of bulked 1T MoS2, the intrinsic strengths of the heterostructures are lower than that of the bulk 2H, especially for that with ZZ interface. Analysis of density of states shows that the electronic properties gradually transmitted from the metallic 1T phase to the semiconducting 2H phase for the structural abrupt interface. The present theoretical results constitute a useful picture for the 2D electronic devices using current MoS2 1T/2H heterostructures and provide vital insights into the other 2D hybrid materials.

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Quasi-Freestanding Monolayer Heterostructure of Graphene and Hexagonal Boron Nitride on Ir(111) with a Zigzag Boundary

Cited by 121 publications

References 48 publications

Two-dimensional Dirac signature of germanene

Two-dimensional Dirac signature of germanene

MoS2-graphene in-plane contact for high interfacial thermal conduction

Structural, mechanical and electronic properties of in-plane 1T/2H phase interface of MoS2 heterostructures

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