Graphene-assisted spontaneous relaxation towards dislocation-free heteroepitaxy

Bae, Sang Hoon; Lu, Kuangye; Han, Yimo; Kim, Sungkyu; Qiao, Kuan; Choi, Chanyeol; Nie, Yifan; Kim, Hyun‐Seok; Kum, Hyun; Chen, Peng; Kong, Wei; Kang, Bongsoon; Kim, Chan-Soo; Lee, Jae Yong; Baek, Yongmin; Shim, Jaewoo; Park, Jinhee; Joo, Minho; Muller, David A.; Lee, Kyusang; Kim, Jeehwan

doi:10.1038/s41565-020-0633-5

Cited by 92 publications

(90 citation statements)

References 32 publications

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“…Such prominent SL examples can be listed as III-V compound semiconductor SLs (i.e., GaAs/AlGaAs and GaInAs/AlInAs) for high electron mobility transistors 3,4 and quantum cascade lasers 5,6 , GaN/AlGaN SLs for light emitting diodes 7,8 and Si/Ge SLs for strained Si CMOS 9 . Therein, the constituent semiconductors are "covalentbonded" across the heterointerfaces with the lattice-matching coherences [10][11][12] , where the two-dimensional (2D) charge carriers form diverse quantum well (QW) structures, depending on the degrees of interlayer coupling strengths 13 . Meanwhile van der Waals (vdW) semiconductors, which often stemmed from transition-metal dichalcogenides (TMDCs, MX 2 , where M and X represent transition-metal ions and chalcogen ions), naturally ensue the inherent 2D con nements within the unit monolayer (ML) across the chemical-bond free vdW gaps [14][15][16] .…”

Section: Main Textmentioning

confidence: 99%

Heteroepitaxial van der Waals semiconductor superlattices

Jin

Lee

Okello

et al. 2021

Preprint

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We report atomic layer-by-layer epitaxial growth of van der Waals (vdW) semiconductor superlattices (SLs) with programmable stacking periodicities, composed of more than two kinds of dissimilar transition-metal dichalcogenide monolayers (MLs), such as MoS2, WS2 and WSe2. The kinetics-controlled vdW epitaxy in the near equilibrium limit by metalorganic chemical vapour depositions enables to achieve accurate ML-by-ML stacking, free of interlayer atomic mixing, resulting in the tunable two-dimensional (2D) vdW electronic systems. We identified coherent atomic stacking orders at the vdW heterointerfaces, and present scaling valley polarized optical excitations that only pertain to a series of 2D type II band alignments.

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Section: Main Textmentioning

confidence: 99%

Heteroepitaxial van der Waals semiconductor superlattices

Jin

Lee

Okello

et al. 2021

Preprint

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“…In a conventional view, this would imply that carbon is not a good candidate for studying the physics of strongly correlated systems. Furthermore, the strength of the spin-orbit coupling in carbon is exceptionally small [16], which constrains its usefulness in studying the topological physics.…”

Section: Introductionmentioning

confidence: 99%

Ferromagnetism and Wigner crystallization in kagome graphene and related structures

Chen

Xie

et al. 2018

Phys. Rev. B

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Interaction in a flat band is magnified due to the divergence in the density of states, which gives rise to a variety of many-body phenomena such as ferromagnetism and Wigner crystallization. Until now, however, most studies of the flat band physics are based on model systems, making their experimental realization a distant future. Here, we propose a class of systems made of real atoms, namely, carbon atoms with realistic physical interactions (dubbed here as Kagome graphene/graphyne). Density functional theory calculations reveal that these Kagome lattices offer a controllable way to realize robust flat bands sufficiently close to the Fermi level. Upon hole doping, they split into spin-polarized bands at different energies to result in a flat-band ferromagnetism. At a half filling, this splitting reaches its highest level of 768 meV. At smaller fillings, e.g., when = 1 6 , on the other hand, a Wigner crystal spontaneously forms, where the electrons form closed loops localized on the grid points of a regular triangular lattice. It breaks the translational symmetry of the original Kagome lattice. We further show that the Kagome lattices exhibit good mechanical stabilities, based on which a possible route for experimental realization of the Kagome graphene is also proposed.Recently, fractional Chern insulators based on the flat band structure have also been extensively studied in lattice systems in the absence of magnetic Landau levels [28][29][30].Kagome lattice is a lattice which can generate flat band. To date, however, most studies on its flat band physics are based on toy models [31][32][33]. Experimentally, available materials with a Kagome lattice are mostly frustrated magnets [34][35][36][37][38][39], which are half-filled Mott insulators.Unfortunately, Fermi level ( ) in such materials is distance away from the flat bands. Given the rich bonding chemistry but simple band structure of carbon, e.g., for graphene only pz states exist near , and exceptional stabilities of its various allotropes, one may ask if it is possible to synthesize carbon-based Kagome or Kagome-like lattices and what would be the physics of strong correlation in them.In this paper, we identify, by first-principles total-energy calculations, a family of twodimensional (2D) carbon Kagome-like structures (to be termed Kagome graphene/graphyne), which can host flat bands and relevant physical phenomena. The most basic structure is the Kagome graphene made of carbon triangles on a regular honeycomb lattice. Noticeably, flat bands appear near in all these structures. Upon hole doping, the spin degeneracy of the flat bands is spontaneously lifted to result in a flat-band ferromagnetism with a large spin splitting. At a 1/6 filling factor of the flat bands, a Wigner crystallization is found, while at other filling factors, various charge density wave patterns are expected. These interesting physical phenomena are interpreted based on a Hubbard model. The possibility of realizing an anomalous quantum Hall effect, as well as the possible routes t...

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“…However, transferring a 2D material layer to a conventional substrate surface can lead to remote epitaxy, reducing film-substrate adhesion, but preserving the transfer of crystallographic information from the substrate to grow a high quality film. [4][5][6][7] However, such techniques have not yet translated well to wafer scale devices. The size of these pristine 2D layers that can be produced and transferred is still technologically limited by complications such as pinholes and surface contamination associated with the wet transfer method.…”

mentioning

confidence: 99%

Spontaneous Relaxation of Heteroepitaxial Thin Films by van der Waals‐Like Bonding on Te‐Terminated Sapphire Substrates

Jovanovic

El‐Sherif

Bassim

et al. 2020

Small

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Heteroepitaxy of thin film materials is a fundamental industrial process for the fabrication of high-quality electronic and electrooptic devices. Conventionally, strong bonding of adatoms on a substrate leads to a coherent thin film below a critical thickness, where the thin film grows strained from its relaxed lattice spacing. Above this critical thickness strain is relieved by defect generation in the thin film. Commercial development of heteroepitaxial technologies is limited by both the availability and cost of lattice-matched substrates. This lattice matching requirement is diminished for van der Waals (vdW) heteroepitaxial systems due to weak interlayer

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Graphene-assisted spontaneous relaxation towards dislocation-free heteroepitaxy

Cited by 92 publications

References 32 publications

Heteroepitaxial van der Waals semiconductor superlattices

Heteroepitaxial van der Waals semiconductor superlattices

Ferromagnetism and Wigner crystallization in kagome graphene and related structures

Spontaneous Relaxation of Heteroepitaxial Thin Films by van der Waals‐Like Bonding on Te‐Terminated Sapphire Substrates

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