Light emission from gold and silver thin films in a scanning tunneling microscope: role of contamination and interpretation of grain structure in photon maps

Walmsley, D.G.; Tan, Thiam-Seng; Dawson, Paul

doi:10.1016/j.susc.2004.09.032

Cited by 14 publications

(13 citation statements)

References 41 publications

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“…This finding is in agreement with previous studies, which found reduced plasmonic emission for tungsten tips as compared to, for example, Au, Ag, or PtIr tips 28, 29. A further suppression of the emission may arise from surface contaminants resulting from the sample preparation under ambient conditions 30. Moreover, even if plasmons could be excited, their coupling to excitons in the NWs is unlikely, since the electric field of the plasmon (perpendicular to the substrate) is perpendicular to the transition dipole of the NW (parallel to the wire axis) 31.…”

Section: Resultssupporting

confidence: 93%

Scanning Tunneling Luminescence of Individual CdSe Nanowires

Lutz

Kabakchiev

Dufaux

et al. 2011

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The local luminescence properties of individual CdSe nanowires composed of segments of zinc blende and wurtzite crystal structures are investigated by low-temperature scanning tunneling luminescence spectroscopy. Light emission from the wires is achieved by the direct injection of holes and electrons, without the need for coupling to tip-induced plasmons in the underlying metal substrate. The photon energy is found to increase with decreasing wire diameter due to exciton confinement. The bulk bandgap extrapolated from the energy versus diameter dependence is consistent with photon emission from the zinc blende-type CdSe sections.

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Section: Resultssupporting

confidence: 93%

Scanning Tunneling Luminescence of Individual CdSe Nanowires

Lutz

Kabakchiev

Dufaux

et al. 2011

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“…In order to stimulate a photoemission-rate variation event, the bias voltage was abruptly increased during scanning to a value of 4.5 V and then reduced back to 2.25 V. A tunneling bias of 4.5 Volts is unstable under ambient conditions and can lead to electrical breakdown of the air over the applicable distance scale of ∼8 Angstroms. Accordingly, an instability is likely to lead to an event that affects the shape and/or the chemistry of the probe surface, which is typically enveloped in a water meniscus under ambient conditions [14] and may operate in the presence of surface adsorbates [6]. Such an event is viewable in each part of Figs.…”

Section: Resultsmentioning

confidence: 99%

“…In a separate context it has been shown that electroluminescent metal clusters can be generated in electromigrated metal break-junctions [5], which are similar to STM junctions in that a tunneling barrier can be created in a spatially localized region. Further, it has been shown that photoemission rates from STM junctions can be highly variable and, during the raster-scan of a sample, line-to-line variations in the emission rate can be significant [6][7][8][9][10]. So far, there has been no study showing that such variations are always the result of a change in the tip-sample cavity, and therefore the gap plasmon mode structure, and not the result of spontaneously generated electroluminescent metal clusters attached to the STM probe/tip.…”

Section: Introductionmentioning

confidence: 99%

The role of gap plasmons in light emission from tunnel junctions

Divitt¹,

Bharadwaj²,

Novotny³

2013

Opt. Express

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Light emission from the junction of a scanning tunneling microscope (STM) is examined in the presence of 20 nm topographical features in thin gold films. These features significantly modify the emission rates of the junction. Contributions to this modification are discriminated by examining emission rates on samples where the material is varied spatially. It is found that the variability in STM photoemission rates between a gold tip and a gold sample under ambient conditions is due to the modification of localized gap plasmon modes and not to the presence of an electroluminescent gold cluster on the STM probe apex.

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“…In order to confirm the role of the gap plasmon in STM-LE, it is necessary to uncover the origin of the line-to-line photoemission intensity variations seen in previous 2-dimensional STM-LE studies [48][49][50][51][52]. These line-to-line variations are typically associated with changes in the probe as it interacts with the sample; however, there have also been reports of electroluminescent (EL) metal clusters being created and/or destroyed within tunnel junctions in a planar geometry [53][54][55].…”

Section: Role Of the Gap Plasmon In Stm-lementioning

confidence: 99%

Localized Light-Matter Interactions with Optical Antennas

Lapin

Bharadwaj

Divitt

et al. 2014

NATO Science for Peace and Security Series B: Physics and Biophysics

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Standard far-field optical elements, such as lenses and mirrors, are only capable of localizing radiation to about half-a-wavelength-the Abbe criterion. Optical antennas facilitate the further localization of radiation into arbitrarily small spatial volumes. Combining the optical antenna with traditional optical microscopy, a technique termed near-field scanning optical microscopy (NSOM), has enabled the study of biological and solid-state samples at high spatial resolution. Since the development of NSOM in the 1980s, the biggest challenge to researchers has been the design and fabrication of optical antennas functioning as optical nearfield probes. We have recently made much progress in the development of widely applicable, and reproducible, optical antennas that provide a high degree of spatial localization. Beyond NSOM, we also explore the electrical excitation, as opposed to photo excitation, of optical antennas with a scanning tunneling microscope (STM). We demonstrate a two-step plasmon-mediated energy conversion from a tunneling current to propagating photons in a smooth gold film as well an extended gold nanowire. We prove that highly localized gap plasmons are first excited in the tunnel gap, which can then couple to propagating plasmons. We elaborate on the role of gap plasmons in explaining the huge variations seen in photon emission yields in the field of STM light emission.

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Light emission from gold and silver thin films in a scanning tunneling microscope: role of contamination and interpretation of grain structure in photon maps

Cited by 14 publications

References 41 publications

Scanning Tunneling Luminescence of Individual CdSe Nanowires

Scanning Tunneling Luminescence of Individual CdSe Nanowires

The role of gap plasmons in light emission from tunnel junctions

Localized Light-Matter Interactions with Optical Antennas

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