Enhancement of gaps in thin graphitic films for heterostructure formation

Hague, J. P.

doi:10.1103/physrevb.89.155415

Cited by 7 publications

(9 citation statements)

References 57 publications

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“…The local Holstein model is a standard approximation to the electron-phonon interaction, chosen here because it significantly simplifies the self-consistent equations, while being in the same general class of interactions [19]. When electron-phonon coupling is moderate, Holstein and Fröhlich interactions lead to qualitatively similar effects on two-dimensional lattices [35,36].…”

Section: Model and Methodsmentioning

confidence: 99%

Bias free gap creation in bilayer graphene

Davenport

Hague²

2014

J. Phys.: Condens. Matter

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For graphene to be utilized in the digital electronics industry the challenge is to create bandgaps of order 1eV as simply as possible. The most successful methods for the creation of gaps in graphene are (a) confining the electrons in nanoribbons, which is technically difficult or (b) placing a potential difference across bilayer graphene, which is limited to gaps of around 300meV for reasonably sized electric fields. Here we propose that electronic band gaps can be created without applying an external electric field, by using the electron-phonon interaction formed when bilayer graphene is sandwiched between highly polarisable ionic materials. We derive and solve selfconsistent equations, finding that a large gap can be formed for intermediate electron-phonon coupling. The gap originates from the amplification of an intrinsic Coulomb interaction due to the proximity of carbon atoms in neighbouring planes. * Jim.Hague@open.ac.uk 0 arXiv:1308.1589v2 [cond-mat.mes-hall]

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Section: Model and Methodsmentioning

confidence: 99%

Bias free gap creation in bilayer graphene

Davenport

Hague²

2014

J. Phys.: Condens. Matter

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“…Lattice vibrations play an important role in the dynamics of charge carriers in 2D materials [14][15][16][17][18][19][20][21][22][23][24]. Particularly, optical phonons of polar substrates localized around sample-substrate interface affect the behavior of charge carrier, which depends strongly on the phonon frequencies and polarizability of a substrate [16,21,[25][26][27][28][29][30][31].…”

Section: Introductionmentioning

confidence: 99%

“…Band gap engineering is an important field aiming at tuning on energy gap of material for potential applications in nanoelectronics. For instance, the electron-phonon interaction can induce a small gap in the band structure of graphene [14,[16][17][18][20][21][22]. Moreover, Wang et al [21] found an energy gap in the zeroth Landau level due to the electron-surface optical phonon interaction arising from the polar substrate, this gap can be tuned by choosing the polarization of substrates and changing the distance between the substrate and graphene.…”

Section: Introductionmentioning

confidence: 99%

Polaronic effects in monolayer black phosphorus on polar substrates

Moğulkoç

Руденко³

et al. 2016

Phys. Rev. B

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We investigate the effect of charge carrier interaction with surface optical phonons on the band properties of monolayer black phosphorus induced by polar substrates. We develop an analytical method based on the Lee-Low-Pines theory to calculate the spectrum of Fröhlich type continuum Hamiltonian in the long-wavelength limit. We examine the modification of a band gap and renormalization of effective masses due to the substrate-related polaronic effect. Our results show that an energy gap in supported monolayer black phosphorus is enlarged depending on a particular substrate and the interlayer distance, z. Among the substrate considered, the largest gap broadening at z = 2.5Å is observed for the Al2O3 substrate, which is found to be ∼ 50 meV. Carrier-phonon coupling also renormalizes the effective masses which is more pronounced along the zigzag direction. Anisotropy of the effective masses becomes stronger by the influence of the polaronic effect corresponding to direction-dependent carrier-phonon coupling. We conclude that substrate phonons have a non-negligible effect on the static band properties of monolayer black phosphorus, which may be further exploited in its experimental and theoretical studies.

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“…Detailed DCA calculations using higher order perturbation theory have been carried out for monolayers of graphene on substrates in Ref. [25] showing only quantitative differences with the mean-field results. We would expect similar quantitative differences in the results for the bilayer systems discussed here, but nothing qualitative.…”

Section: Discussionmentioning

confidence: 99%

“…Extended Holstein and local Holstein forms of interaction have qualitatively similar properties. On the mean-field level, Holstein and Fröhlich interactions are identical [25] due to averaging of the interaction across the Brillouin zone [26]. Therefore, the form of the interaction is taken to be of the local, Holstein, form [27],…”

Section: Modelmentioning

confidence: 99%

Role of substrate induced electron–phonon interactions in biased graphitic bilayers

Davenport¹,

Hague²

2016

J. Phys.: Condens. Matter

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Bilayers of graphitic materials have potential applications in field effect transistors (FETs). A potential difference applied between certain ionic bilayers made from insulating graphitic materials such as BN, ZnO and AlN could reduce gap sizes, turning them into useful semiconductors. On the other hand, opening of a small semiconducting gap occurs in graphene bilayers under applied field. The aim here is to investigate to what extent substrate induced electron-phonon interactions (EPIs) modify this gap change. We examine EPIs in several lattice configurations of graphitic bilayers, using a perturbative approach. The typical effect of EPIs on the ionic bilayers is an undesirable gap widening. The size of this gap change varies considerably with lattice structure and the magnitude of the bias. When bias is larger than the non-interacting gap size, EPIs have the smallest effect on the bandgap, especially in configurations with [Formula: see text] and AB structures. Thus careful selection of substrate, lattice configuration and bias strength to minimise the effects of EPIs could be important for optimising the properties of electronic devices. We use parameters related to BN in this article. In practice, the results presented here are broadly applicable to other graphitic bilayers, and are likely to be qualitatively similar in metal dichalcogenide bilayers such as MoS2, which are already of high interest for their use in FETs.

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Enhancement of gaps in thin graphitic films for heterostructure formation

Cited by 7 publications

References 57 publications

Bias free gap creation in bilayer graphene

Bias free gap creation in bilayer graphene

Polaronic effects in monolayer black phosphorus on polar substrates

Role of substrate induced electron–phonon interactions in biased graphitic bilayers

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