Identification of pristine and defective graphene nanoribbons by phonon signatures in the electron transport characteristics

Christensen, Rasmus Bjerregaard; Frederiksen, Thomas; Brandbyge, Mads

doi:10.1103/physrevb.91.075434

Cited by 14 publications

(19 citation statements)

References 62 publications

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“…The quantum transport properties of GNR-based devices have been extensively studied with first-principles methods, for instance in the contexts of chemical functionalization 32 , optical excitations 33,34 , thermoelectrics [35][36][37] , local current-density patterns 38 , vibra-tional excitations 39 , and spin-scattering in ZGNRs [40][41][42] and hydrogenated AGNRs. 43,44 .…”

Section: Introductionmentioning

confidence: 99%

A tunable electronic beam splitter realized with crossed graphene nanoribbons

Brandimarte

Engelund

Papior

et al. 2017

The Journal of Chemical Physics

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Graphene nanoribbons (GNRs) are promising components in future nanoelectronics due to the large mobility of graphene electrons and their tunable electronic band gap in combination with recent experimental developments of on-surface chemistry strategies for their growth. Here we explore a prototype 4-terminal semiconducting device formed by two crossed armchair GNRs (AGNRs) using state-of-the-art first-principles transport methods. We analyze in detail the roles of intersection angle, stacking order, inter -GNR separation, and finite voltages on the transport characteristics. Interestingly, when the AGNRs intersect at θ = 60 • , electrons injected from one terminal can be split into two outgoing waves with a tunable ratio around 50% and with almost negligible back-reflection. The splitted electron wave is found to propagate partly straight across the intersection region in one ribbon and partly in one direction of the other ribbon, i.e., in analogy of an optical beam splitter. Our simulations further identify realistic conditions for which this semiconducting device can act as a mechanically controllable electronic beam splitter with possible applications in carbonbased quantum electronic circuits and electron optics. We rationalize our findings with a simple model that suggests that electronic beam splitters can generally be realized with crossed GNRs. arXiv:1611.03337v1 [cond-mat.mes-hall]

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Section: Introductionmentioning

confidence: 99%

A tunable electronic beam splitter realized with crossed graphene nanoribbons

Brandimarte

Engelund

Papior

et al. 2017

The Journal of Chemical Physics

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“…1(a) where the current is passed through a short ribbon [21,[47][48][49] at the narrowest point that connects two graphene electrodes. Looking at the transmission probability for an electron to cross the device, Fig.…”

Section: System and Methodsmentioning

confidence: 99%

Inelastic vibrational signals in electron transport across graphene nanoconstrictions

et al. 2016

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We present calculations of the inelastic vibrational signals in the electrical current through a graphene nanoconstriction. We find that the inelastic signals are only present when the Fermi-level position is tuned to electron transmission resonances, thus, providing a fingerprint which can link an electron transmission resonance to originate from the nanoconstriction. The calculations are based on a novel first-principles method which includes the phonon broadening due to coupling with phonons in the electrodes. We find that the signals are modified due to the strong coupling to the electrodes, however, still remain as robust fingerprints of the vibrations in the nanoconstriction. We investigate the effect of including the full self-consistent potential drop due to finite bias and gate doping on the calculations and find this to be of minor importance.

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“…Atomically precise ribbons [ 2 ], as well as more advanced ribbon-based structures [ 3 – 4 ], have been fabricated “bottom-up” on metal surfaces. The conductance through the ribbons has been investigated using STM [ 5 ], and the signals of electron vibrations in the current have been addressed by theory [ 6 ].…”

Section: Introductionmentioning

confidence: 99%

Current-induced runaway vibrations in dehydrogenated graphene nanoribbons

Christensen¹,

Kai-Lun²,

Hedegård³

et al. 2016

Beilstein J. Nanotechnol.

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SummaryWe employ a semi-classical Langevin approach to study current-induced atomic dynamics in a partially dehydrogenated armchair graphene nanoribbon. All parameters are obtained from density functional theory. The dehydrogenated carbon dimers behave as effective impurities, whose motion decouples from the rest of carbon atoms. The electrical current can couple the dimer motion in a coherent fashion. The coupling, which is mediated by nonconservative and pseudo-magnetic current-induced forces, change the atomic dynamics, and thereby show their signature in this simple system. We study the atomic dynamics and current-induced vibrational instabilities using a simplified eigen-mode analysis. Our study illustrates how armchair nanoribbons can serve as a possible testbed for probing the current-induced forces.

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Identification of pristine and defective graphene nanoribbons by phonon signatures in the electron transport characteristics

Cited by 14 publications

References 62 publications

A tunable electronic beam splitter realized with crossed graphene nanoribbons

A tunable electronic beam splitter realized with crossed graphene nanoribbons

Inelastic vibrational signals in electron transport across graphene nanoconstrictions

Current-induced runaway vibrations in dehydrogenated graphene nanoribbons

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