Tunneling characteristics in chemical vapor deposited graphene–hexagonal boron nitride–graphene junctions

Roy, Tania; Liu, Lei; Barrera, Sergio C. de la; Chakrabarti, Bhaswar; Hesabi, Z. Razavi; Joiner, Corey A.; Feenstra, R. M.; Gu, Gong; Vogel, Eric M.

doi:10.1063/1.4870073

Cited by 52 publications

(48 citation statements)

References 12 publications

(23 reference statements)

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“…By using this fact we obtain E f e = |e · V h | − |E f ield | − |E f h | = −0.07 eV (8) and hence we obtain a hole concentration of n e = 3.54 · 10 11 cm −2 .…”

Section: Supporting Informationmentioning

confidence: 81%

Sub-bandgap Voltage Electroluminescence and Magneto-oscillations in a WSe₂ Light-Emitting van der Waals Heterostructure

et al. 2017

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We report on experimental investigations of an electrically driven WSe 2 based lightemitting van der Waals heterostructure. We observe a threshold voltage for electroluminescence significantly lower than the corresponding single particle band gap of mono-1 arXiv:1702.08333v1 [cond-mat.mes-hall] 27 Feb 2017 layer WSe 2 . This observation can be interpreted by considering the Coulomb interaction and a tunneling process involving excitons, well beyond the picture of independent charge carriers. An applied magnetic field reveals pronounced magneto-oscillations in the electroluminescence of the free exciton emission intensity with a 1/B-periodicity.This effect is ascribed to a modulation of the tunneling probability resulting from the Landau quantization in the graphene electrodes. A sharp feature in the differential conductance indicates that the Fermi level is pinned and allows for an estimation of the acceptor binding energy. Based on this idea, a few prototype devices, such as tunneling transistors 3-11 and/or lightemitting tunneling diodes, [12][13][14][15][16] have been fabricated and successfully tested. However, further work is necessary in order to better characterize such structures, to learn more about their electronic and optical properties, with the aim to properly design device operation.Here, we unveil new facets of light emitting vdW heterostructures, with reference to the issue of the alignment of electronic bands, effects of Coulomb interaction and a subtle but still active role of the graphene electrodes in these devices. We report on optoelectronic measurements performed on a WSe 2 -based tunneling light-emitting diode. The differential tunneling conductance of our structure shows a large zero bias anomaly (peak), which we ascribe to pinning of the Fermi energy at the WSe 2 impurity/acceptor level. A conceivable scenario for the evolution of the band alignment as a function of the bias voltage is proposed. Strikingly, the bias-potential onset for the electroluminescence is found to coincide with the 2 energy of the free exciton of the WSe 2 monolayer (and not with the energy of a single-particle bandgap). This fact points out the relevant role of Coulomb interactions between electrically injected carriers on the tunneling processes in our device. Furthermore, pronounced magnetooscillations are observed in the electroluminescence emission intensity measured as a function of magnetic field applied perpendicularly to the layer planes. These oscillations, periodic with the inverse of the magnetic field, reflect the modulation of the efficiency of carrier tunneling and are caused by the Landau quantization of the two-dimensional graphene electrodes.We studied a light-emitting diode structure 12,13 that is based on a WSe 2 monolayer as the active part. The layer sequence for this device was Si / SiO 2 / hBN / graphene / hBN / WSe 2 / hBN / graphene. The emission area of the structure is presented on the microscope image in Figure 1 (a). Figure 1 (b) depicts a schematic drawing of the layered str...

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“…By using this fact we obtain E f e = |e · V h | − |E f ield | − |E f h | = −0.07 eV (8) and hence we obtain a hole concentration of n e = 3.54 · 10 11 cm −2 .…”

Section: Supporting Informationmentioning

confidence: 81%

Sub-bandgap Voltage Electroluminescence and Magneto-oscillations in a WSe₂ Light-Emitting van der Waals Heterostructure

et al. 2017

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“…110, in contrast to the zero-temperature approximation employed in the computational results of our previous work. [2,110,111] We rst consider results obtained on devices that do not display NDR in their characteristics, presumably due to a relatively small coherence length for the tunneling. In Fig.…”

Section: Comparison To Experimentsmentioning

confidence: 99%

“…2 An additional distinction between the form introduced in Eq. (3.1) and that used previously in Ref.…”

Section: µMmentioning

confidence: 99%

“…As also discussed there, from comparison of theory to experiment for other devices we derive an o set value closer to the middle of the band gap. [2] In any case, in order to be de nite as to our choice of decay constant to use in our simulations, we take the experimental value of 6.0 nm −1 and we assign that to the midgap κ 0 value. This experimental value is slightly greater than that derived from the tight-binding model discussed above, but still in reasonable agreement considering the uncertainties of the theory.…”

Section: Hexagonal Boron Nitride Tunneling Barriermentioning

confidence: 99%

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Layered Two-Dimensional Heterostructures and Their Tunneling Characteristics

Barrera¹

2017

Springer Theses

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“…[10][11][12] The introduction of an insulating layer, such as hexagonal boron-nitride (hBN), yields a graphene-insulator-graphene (G-I-G) stack with similar electronic properties. Theoretical study of the current-voltage characteristics of these G-I-G stacks with misaligned Dirac cones predicts negative differential resistance (NDR) [2,[13][14][15] as well as flat regions in the current [16]. Recently, resonant tunneling has been measured between two rotationally misaligned graphene sheets separated by an hBN layer [17].…”

Section: Introductionmentioning

confidence: 99%

Inter-ribbon tunneling in graphene: An atomistic Bardeen approach

Put

Vandenberghe

Sorée

et al. 2016

Journal of Applied Physics

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A weakly coupled system of two crossed graphene nanoribbons exhibits direct tunneling due to the overlap of the wavefunctions of both ribbons. We apply the Bardeen transfer Hamiltonian formalism, using atomistic band structure calculations to account for the effect of the atomic structure on the tunneling process. The strong quantum-size confinement of the nanoribbons is mirrored by the one-dimensional character of the electronic structure, resulting in properties that differ significantly from the case of inter-layer tunneling, where tunneling occurs between bulk two-dimensional graphene sheets. The current-voltage characteristics of the inter-ribbon tunneling structures exhibit resonance, as well as stepwise increases in current. Both features are caused by the energetic alignment of one-dimensional peaks in the density-of-states of the ribbons. Resonant tunneling occurs if the sign of the curvature of the coupled energy bands is equal, whereas a step-like increase of the current occurs if the signs are opposite. Changing the doping modulates the onset-voltage of the effects as well as their magnitude. Doping through electrostatic gating makes these structures promising for application towards steep slope switching devices. Using the atomistic empirical pseudopotentials based Bardeen transfer Hamiltonian method, inter-ribbon tunneling can be studied for the whole range of two-dimensional materials, such as transition metal dichalcogenides. The effects of resonance and of step-like increases of the current we observe in graphene ribbons, are also expected in ribbons made from these alternative two-dimensional materials, because these effects are manifestations of the one-dimensional character of the densityof-states. * Electronic mail: maarten.vandeput@uantwerpen.be 2

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Tunneling characteristics in chemical vapor deposited graphene–hexagonal boron nitride–graphene junctions

Cited by 52 publications

References 12 publications

Sub-bandgap Voltage Electroluminescence and Magneto-oscillations in a WSe₂ Light-Emitting van der Waals Heterostructure

Sub-bandgap Voltage Electroluminescence and Magneto-oscillations in a WSe₂ Light-Emitting van der Waals Heterostructure

Layered Two-Dimensional Heterostructures and Their Tunneling Characteristics

Inter-ribbon tunneling in graphene: An atomistic Bardeen approach

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Tunneling characteristics in chemical vapor deposited graphene–hexagonal boron nitride–graphene junctions

Cited by 52 publications

References 12 publications

Sub-bandgap Voltage Electroluminescence and Magneto-oscillations in a WSe2 Light-Emitting van der Waals Heterostructure

Sub-bandgap Voltage Electroluminescence and Magneto-oscillations in a WSe2 Light-Emitting van der Waals Heterostructure

Layered Two-Dimensional Heterostructures and Their Tunneling Characteristics

Inter-ribbon tunneling in graphene: An atomistic Bardeen approach

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Product

Resources

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Sub-bandgap Voltage Electroluminescence and Magneto-oscillations in a WSe₂ Light-Emitting van der Waals Heterostructure

Sub-bandgap Voltage Electroluminescence and Magneto-oscillations in a WSe₂ Light-Emitting van der Waals Heterostructure