Electronic properties of two-dimensional systems

Ando, Tsuneya; Fowler, A. B.; Stern, Frank

doi:10.1103/revmodphys.54.437

Cited by 7,297 publications

(4,601 citation statements)

References 1,592 publications

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“…In 2D TMDC layers, transport and scattering of the carriers are confined to the plane of the material. The mobility of carriers is affected by the following main scattering mechanisms 100,101 : (i) acoustic and optical phonon scattering; (ii) Coulomb scattering at charged impurities; (iii) surface interface phonon scattering; and (iv) roughness scattering. The degree to which these scattering mechanisms affect the carrier mobility is also influenced by layer thickness, carrier density, temperature, effective carrier mass, electronic band structure and phonon band structure.…”

Section: Electrical Transport and Devicesmentioning

confidence: 99%

Electronics and optoelectronics of two-dimensional transition metal dichalcogenides

et al. 2012

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699M any two-dimensional (2D) materials exist in bulk form as stacks of strongly bonded layers with weak interlayer attraction, allowing exfoliation into individual, atomically thin layers 1 . The form receiving the most attention today is graphene, the monolayer counterpart of graphite. The electronic band structure of graphene has a linear dispersion near the K point, and charge carriers can be described as massless Dirac fermions, providing scientists with an abundance of new physics 2,3 . Graphene is a unique example of an extremely thin electrical and thermal conductor 4 , with high carrier mobility 5 , and surprising molecular barrier properties 6,7 .Many other 2D materials are known, such as the TMDCs 8,9 , transition metal oxides including titania-and perovskite-based oxides 10,11 , and graphene analogues such as boron nitride (BN) 12,13 . In particular, TMDCs show a wide range of electronic, optical, mechanical, chemical and thermal properties that have been studied by researchers for decades 9,14,15 . There is at present a resurgence of scientific and engineering interest in TMDCs in their atomically thin 2D forms because of recent advances in sample preparation, optical detection, transfer and manipulation of 2D materials, and physical understanding of 2D materials learned from graphene.The 2D exfoliated versions of TMDCs offer properties that are complementary to yet distinct from those in graphene. Graphene displays an exceptionally high carrier mobility exceeding 10 6 cm 2 V -1 s -1 at 2 K (ref. 16) and exceeding 10 5 cm 2 V -1 s -1 at room temperature for devices encapsulated in BN dielectric layers 5 ; because pristine graphene lacks a bandgap, however, fieldeffect transistors (FETs) made from graphene cannot be effectively switched off and have low on/off switching ratios. Bandgaps can be engineered in graphene using nanostructuring [17][18][19] , chemical functionalization 20 and applying a high electric field to bilayer graphene 21 , but these methods add complexity and diminish mobility. In contrast, several 2D TMDCs possess sizable bandgaps around 1-2 eV (refs 9,14), promising interesting new FET and optoelectronic devices.TMDCs are a class of materials with the formula MX 2 , where M is a transition metal element from group IV (Ti, Zr, Hf and so on), group V (for instance V, Nb or Ta) or group VI (Mo, W and so on), and X is a chalcogen (S, Se or Te). These materials form layered structures of the form X-M-X, with the chalcogen atoms in two hexagonal planes separated by a plane of metal atoms, as shown in Fig. 1a. Adjacent layers are weakly held together to form the bulk crystal in a variety of polytypes, which vary in stacking orders and metal atom coordination, as shown in Fig. 1e. The overall symmetry of TMDCs is hexagonal or rhombohedral, and the metal atoms have octahedral or trigonal prismatic coordination. The electronic properties of TMDCs range from metallic to semiconducting, as summarized in Table 1. There are also TMDCs that exhibit exotic behaviours such as charge density waves ...

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Section: Electrical Transport and Devicesmentioning

confidence: 99%

Electronics and optoelectronics of two-dimensional transition metal dichalcogenides

et al. 2012

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“…63. By applying an electric ÿeld, a two-dimensional charge layer accumulates on the surface of the semiconductor adjacent to the insulator, whose density can simply be changed by varying the ÿeld strength (For details see [26].). Similar geometries have been used to observe the quantum Hall e ects and the metal-insulator transition by varying the density.…”

Section: The Two-dimensional Electron Gasmentioning

confidence: 99%

Singular or non-Fermi liquids

2002

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“…1−14 One expects that plasmon waves in graphene can be squeezed into a much smaller volume 11,13 than in noble metals routinely used in plasmonics and, importantly, can be manipulated by external gate voltage. A Dirac-like linear electronic dispersion and zero bandgap in graphene make its electromagnetic response rather unusual compared to other known two-dimensional conductors, such as 2D electron gases (2DEGs) in semiconductor heterostructures, 15 even though the basic description of the propagating plasma modes is essentially the same. 1,2 In order to observe plasmonic absorption optically one generally has to break the translational invariance of the system.…”

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confidence: 99%

Intrinsic Terahertz Plasmons and Magnetoplasmons in Large Scale Monolayer Graphene

et al. 2012

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We show that in graphene epitaxially grown on SiC the Drude absorption is transformed into a strong terahertz plasmonic peak due to natural nanoscale inhomogeneities, such as substrate terraces and wrinkles. The excitation of the plasmon modifies dramatically the magneto-optical response and in particular the Faraday rotation. This makes graphene a unique playground for plasmon-controlled magneto-optical phenomena thanks to a cyclotron mass 2 orders of magnitude smaller than in conventional plasmonic materials such as noble metals.

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Electronic properties of two-dimensional systems

Cited by 7,297 publications

References 1,592 publications

Electronics and optoelectronics of two-dimensional transition metal dichalcogenides

Electronics and optoelectronics of two-dimensional transition metal dichalcogenides

Singular or non-Fermi liquids

Intrinsic Terahertz Plasmons and Magnetoplasmons in Large Scale Monolayer Graphene

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