The role of titanium in electromigrated tunnel junctions

Frimmer, Martin; Puebla‐Hellmann, Gabriel; Wallraff, Andreas; Novotny, Lukas

doi:10.1063/1.4903748

Cited by 8 publications

(8 citation statements)

References 25 publications

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“…In this example, the estimated gap is 6.6 Å and the barrier is weakly asymmetric with respect to the applied polarity (negligible ∆Φ). The extracted barrier height (Φ = 1.8 eV) is much smaller than the work function of Au, but is consistent with previous reports of reduced barrier height in similar systems [17,27,[30][31][32].…”

Section: Electrical Characterizationsupporting

confidence: 91%

Optical Rectification and Thermal Currents in Optical Tunneling Gap Antennas

Mennementeuil¹,

Buret²,

Francs³

et al. 2021

Preprint

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Electrically-contacted optical gap antennas are nanoscale interface devices enabling the transduction between photons and electrons. This new generation of devices captures visible to near infrared electromagnetic radiation and converts the incident energy in a direct-current (DC) electrical signal. The nanoscale rectenna is usually constituted of metal elements (e.g. gold). Light absorption by the metal contacts may lead to additional thermal effects which need to be taken into account to understand the complete photoresponse of the device. The purpose of this communication is to discuss the contribution of laser-induced thermo-electric effects in the photo-assisted electronic transport.

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Section: Electrical Characterizationsupporting

confidence: 91%

Optical Rectification and Thermal Currents in Optical Tunneling Gap Antennas

Mennementeuil¹,

Buret²,

Francs³

et al. 2021

Preprint

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“…Two clear minima are identified with respect to bias polarity at nearly symmetric values 1/ = −3.51 ± 0.16 V −1 and 1/ = 3.5 ± 0.09 V −1 , corresponding to an average transition voltage | V t | = 0.28 V. It is immediately obvious here that the transition voltage inferred from the Fowler–Nordheim plot differs significantly from the average barrier height resulting from Simmons’ model ( = 1.11 eV). However, such a low value of is consistently reported in Au tunnel junctions [ 19 , 26 , 41 , 45 ] and is tentatively attributed to surface states on the electrodes [ 41 , 46 ], the effect of image charges [ 47 ], the presence of protruding atoms [ 48 ] or a Schottky contact [ 45 ]. Despite this body of work, the interpretation of the Fowler–Nordheim plot and the transition voltage has been debated in the past.…”

Section: Resultsmentioning

confidence: 98%

Electromigrated electrical optical antennas for transducing electrons and photons at the nanoscale

Dasgupta¹,

Buret²,

Cazier³

et al. 2018

Beilstein J. Nanotechnol.

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Background: Electrically controlled optical metal antennas are an emerging class of nanodevices enabling a bilateral transduction between electrons and photons. At the heart of the device is a tunnel junction that may either emit light upon injection of electrons or generate an electrical current when excited by a light wave. The current study explores a technological route for producing these functional units based upon the electromigration of metal constrictions. Results: We combine multiple nanofabrication steps to realize in-plane tunneling junctions made of two gold electrodes, separated by a sub-nanometer gap acting as the feedgap of an optical antenna. We electrically characterize the transport properties of the junctions in the light of the Fowler–Nordheim representation and the Simmons model for electron tunneling. We demonstrate light emission from the feedgap upon electron injection and show examples of how this nanoscale light source can be coupled to waveguiding structures. Conclusion: Electromigrated in-plane tunneling optical antennas feature interesting properties with their unique functionality enabling interfacing electrons and photons at the atomic scale and with the same device. This technology may open new routes for device-to-device communication and for interconnecting an electronic control layer to a photonic architecture.

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“…Ideal Au−air−Au tunnel junctions are expected to show a barrier height of 5.1 eV. 25 However, reduced barrier heights are commonly observed for tunnel junctions operating under ambient conditions. 26 For sufficiently large voltages, V > 2 V, we observe an optical response from the device in the form of a diffraction-limited electroluminescence spot as shown in the inset of Figure 2a.…”

mentioning

confidence: 99%

“…A Simmons fit to the experimental I – V curve yields a barrier height of 2.0 eV and a gap size on the order of 1 nm. Ideal Au–air–Au tunnel junctions are expected to show a barrier height of 5.1 eV . However, reduced barrier heights are commonly observed for tunnel junctions operating under ambient conditions .…”

mentioning

confidence: 99%

Electrically Driven Unidirectional Optical Nanoantennas

et al. 2017

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Directional antennas revolutionized modern day telecommunication by enabling precise beaming of radio and microwave signals with minimal loss of energy. Similarly, directional optical nanoantennas are expected to pave the way toward on-chip wireless communication and information processing. Currently, on-chip integration of such antennas is hampered by their multielement design or the requirement of complicated excitation schemes. Here, we experimentally demonstrate electrical driving of in-plane tunneling nanoantennas to achieve broadband unidirectional emission of light. Far-field interference, as a result of the spectral overlap between the dipolar emission of the tunnel junction and the fundamental quadrupole-like resonance of the nanoantenna, gives rise to a directional radiation pattern. By tuning this overlap using the applied voltage, we record directivities as high as 5 dB. In addition to electrical tunability, we also demonstrate passive tunability of the directivity using the antenna geometry. These fully configurable electrically driven nanoantennas provide a simple way to direct optical energy on-chip using an extremely small device footprint.

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The role of titanium in electromigrated tunnel junctions

Cited by 8 publications

References 25 publications

Optical Rectification and Thermal Currents in Optical Tunneling Gap Antennas

Optical Rectification and Thermal Currents in Optical Tunneling Gap Antennas

Electromigrated electrical optical antennas for transducing electrons and photons at the nanoscale

Electrically Driven Unidirectional Optical Nanoantennas

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