Epitaxial growth of massively parallel germanium nanoribbons by segregation through Ag(1 1 0) thin films on Ge(1 1 0)

Yuhara, J.; Shimazu, Haruo; Kobayashi, Masato; Ohta, Akio; Miyazaki, Seiichi; Takakura, Shinichi; Nakatake, M.; Lay, G. Le

doi:10.1016/j.apsusc.2021.149236

Cited by 8 publications

(9 citation statements)

References 33 publications

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“…To further illustrate that this field-induced transition to the Dirac semimetal is of a general nature, we investigate heavier group-IV congeners of graphene nanoribbons, that is, silicene and germanene nanoribbons. , Such nanostructures have been epitaxially grown on various substrates, − including inert substrates, − that are instrumental to preserving the ideal honeycomb configuration, and subsequently integrated as active channels into electronic devices. , Figure d displays the atomic structure of hydrogen-terminated silicene and germanene nanoribbons. Unlike carbon, the arrangement of silicon and germanium atoms in a honeycomb lattice is unstable in a planar geometry and is subject to a structural distortion that consists of a relative out-of-plane displacement of the two sublattices by 0.53 and 0.63 Å, respectively. , Despite the marked difference in the crystal structure, the field-induced semiconductor-to-semimetal transition is preserved, as evident from Figure e,f.…”

Section: Electric Route To Dirac Fermions In Agnrsmentioning

confidence: 99%

Electrically Induced Dirac Fermions in Graphene Nanoribbons

et al. 2021

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Graphene nanoribbons are widely regarded as promising building blocks for next-generation carbon-based devices. A critical issue to their prospective applications is whether their electronic structure can be externally controlled. Here, we combine simple model Hamiltonians with extensive first-principles calculations to investigate the response of armchair graphene nanoribbons to transverse electric fields. Such fields can be achieved either upon laterally gating the nanoribbon or incorporating ambipolar chemical codopants along the edges. We reveal that the field induces a semiconductor-to-semimetal transition with the semimetallic phase featuring zero-energy Dirac fermions that propagate along the armchair edges. The transition occurs at critical fields that scale inversely with the width of the nanoribbons. These findings are universal to group-IV honeycomb lattices, including silicene and germanene nanoribbons, irrespective of the type of edge termination. Overall, our results create new opportunities to electrically engineer Dirac semimetallic phases in otherwise semiconducting graphene-like nanoribbons.

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Section: Electric Route To Dirac Fermions In Agnrsmentioning

confidence: 99%

Electrically Induced Dirac Fermions in Graphene Nanoribbons

et al. 2021

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“…[9][10][11][12][13][14][15] The formation of not only ultrathin Ge crystalline but also germanene has also been performed by annealing a thin metal layer on a Ge substrate. [16][17][18][19][20][21][22][23][24][25] In our previous work, it was found that a hetero-epitaxial Ag (111) layer was grown on wet-cleaned Ge(111) and Si(111) surfaces by the thermal evaporation of Ag from the analyses of X-ray diffraction (XRD) patterns and electron backscatter diffraction (EBSD) images. [16][17][18] For an atomic layer deposited Al oxide capping layer/Ag(111) stack on Ge(111) and Si(111) structures, the formation of Ge and Si at the Al oxide/Ag interface by thermal annealing were clarified.…”

Section: Introductionmentioning

confidence: 99%

“…21) In an Ag(110)/Ge(110) structure, Ge quantum nanoribbons can be formed by the segregation of Ge atoms on the Ag(110) surface at above 350 °C. 22) To protect the segregated Ge layer from oxidation, the formation of germanene at the van der Waals materials (graphene and BN)/metal interface has been reported. 23,24) Recently, Al is attracted our particular interest as a crystalline growth template instead of Ag because of their similar physical properties such as eutectic reaction with Ge (eutectic temperature: 420 °C for Al-Ge and 651 °C for Ag-Ge system), crystallographic structure (fcc), and lattice constant (Ag: 0.4079 nm, Al: 0.4046 nm).…”

Section: Introductionmentioning

confidence: 99%

Segregation control for ultrathin Ge layer in Al/Ge(111) system

Ohta

Kobayashi

Taoka

et al. 2021

Jpn. J. Appl. Phys.

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An impact of the vacuum anneal of Al/Ge(111) structure on the Ge segregation has been investigated to get an insight into the precise control of ultrathin Ge crystalline growth. The Al/Ge(111) structure was prepared by thermal evaporation of Al on wet-cleaned Ge(111) and then vacuum annealed without air exposure to promote Ge formation on the Al surface. The Ge formation and its chemical bonding features were evaluated by X-ray photoelectron spectroscopy analysis. In addition, changes in the average Ge thickness depending on annealing temperature and time were crudely estimated. We found that the annealing temperature had a greater effect than time on the control of sub-nanometer scale Ge growth.

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“…The initial syntheses of silicene, germanene, stanene, and plumbene (called group IV Xenes) and most following works have been usually carried out by molecular beam epitaxy (MBE) on precious metals [5][6][7][8][9]. Conversely, there are only few reports on the epitaxial growth of such Xenes using atomic segregation epitaxy [9][10][11][12][13][14][15]. Typically, on silver (111) substrates, a germanene phase forming a clear 9√3 × 9√3R30 • moiré structure upon annealing at 142 • C was reported in 2014 [16], and two types of striped and quasi-freestanding domains prepared at 150 • C were published in 2018 [17].…”

Section: Introductionmentioning

confidence: 99%

Single germanene phase formed by segregation through Al(111) thin films on Ge(111)

et al. 2021

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We have obtained single phase monolayer germanene on aluminum (111) thin films grown on a germanium (111) template by atomic segregation epitaxy, a preparation method differing from molecular beam epitaxy used in previous works. This 2 × 2 reconstructed germanene phase matching an Al(111)3 × 3 supercell has been prepared in large areas upon annealing at 430 • C. Detailed studies have been carried out using scanning tunneling microscopy (STM), low-energy electron diffraction, Auger electron spectroscopy, and synchrotron radiation photoemission spectroscopy. First-principles calculations based on the density function theory along with atomic-scale STM images reveal the atomic structure with one protruding Ge atom per 2 × 2 germanene supercell and a characteristic dispersing band originating from the germanene sheet slightly coupled to the first layer Al atoms underneath. Instead, upon annealing at lower temperatures, multi-phase regions comprise twisted germanene domains in correspondence with an Al(111)√7×√7 R ± 19.1 • superstructure as obtained in previous studies.

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Epitaxial growth of massively parallel germanium nanoribbons by segregation through Ag(1 1 0) thin films on Ge(1 1 0)

Cited by 8 publications

References 33 publications

Electrically Induced Dirac Fermions in Graphene Nanoribbons

Electrically Induced Dirac Fermions in Graphene Nanoribbons

Segregation control for ultrathin Ge layer in Al/Ge(111) system

Single germanene phase formed by segregation through Al(111) thin films on Ge(111)

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