Electron emission by long and short wavelength lasers: Essentials for the design of plasmonic photocathodes

Forati, Ebrahim; Sievenpiper, Daniel F.

doi:10.1063/1.5031882

Cited by 8 publications

(10 citation statements)

References 43 publications

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“…This happens despite the low photon energy, which is noticeably less than the work function φ0. The results provided in the recent works [5,12,13,25,26] demonstrate the experimental observation of the tunnel photoemission. It is obvious that efficiency of the analyzed structure of the photosensor will improve if an additional adjustment element is introduced that ensures implementation of the matching principle to the localization zones of the absorbed optical and electrostatic fields.…”

Section: A Model For the Tunnel Photocurrent Within The Structuresupporting

confidence: 60%

“…This happens despite the low photon energy, which is noticeably less than the work function ϕ 0 . The results provided in the recent works [5,12,13,25,26] demonstrate the experimental observation of the tunnel photoemission.…”

Section: A Model For the Tunnel Photocurrent Within The Structuresupporting

confidence: 60%

“…The probability of tunneling of nonequilibrium photoelectrons generated in the surface layer of molybdenum with the thickness Lτ with the energy EF + hν and the momentum directed normally to the surface of the emitter is determined by the following relationship [13,21]: (4) Here, hν is the energy of irradiating photons, y ≡ (e 3 F) Accounting of the temperature effects carried out in the work of [12] allowed us to obtain the relations needed to determine the tunneling probability of hot electrons that reach the surface of the emitter Pλ, and the tunneling photocurrent density IPh from the metal emitter depending on the electrostatic field F and the monochromatic light intensity Iλ. Figure 6.…”

Section: Appl Sci 2019 9 X For Peer Review 9 Of 16mentioning

confidence: 99%

“…Accounting of the temperature effects carried out in the work of [12] allowed us to obtain the relations needed to determine the tunneling probability of hot electrons that reach the surface of the emitter P λ , and the tunneling photocurrent density I Ph from the metal emitter depending on the electrostatic field F and the monochromatic light intensity I λ .…”

Section: Appl Sci 2019 9 X For Peer Review 9 Of 16mentioning

confidence: 99%

“…In particular, this approach was successfully applied using nanosized gold plasmon structures [5,6]. The periodicity of the arrays of planar emitters [5] and bulk emitters [6,12] was reduced to 1 µm; this value corresponds to the marginal possibilities of modern technologies based on the e-beam lithography. The gaps between the emitters were equal to 200 nm in the case of the planar structure, and 150 nm in the case of the bulk emitters.…”

Section: Introductionmentioning

confidence: 99%

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A Visible and Near-IR Tunnel Photosensor with a Nanoscale Metal Emitter: The Effect of Matching of Hot Electrons Localization Zones and a Strong Electrostatic Field

et al. 2019

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The results of the research and design of a novel vacuum photosensor with a planar molybdenum blade structure are presented. The advanced prototype implements the principle of an increasing penetrability of the Schottky barrier for the metal–vacuum interfaces under the action of an external strong electrostatic field. Theoretical and experimental substantiation of the photosensor performance in a wide range of wavelengths (from 430 to 680 nm and from 800 to 1064 nm) beyond the threshold of the classical photoelectric effect is given. The finite element method was applied to calculate distribution of the optical and electrostatic fields inside the photosensor structure. The sensor current-to-light response was studied using the periodic pulsed irradiation with the tunable wavelength. It was shown that the nanoscale localization zones of two types are formed near the surface of the blade tip: the zone of an increased concentration of hot electrons localized inside the molybdenum blade, and the zone with an increased strength of the external electrostatic field localized outside the blade. In general, the mutual positions of these zones may not coincide, whereas the position of the first-type localization zone significantly varies with the changes in the wavelength of the irradiating light. This causes features in the spectrum of the quantum yield of the photosensor such as expressed non-monotonic behavior and occurrence of sharp dips. The design of the photosensor that provides matching of the positions for both types of localization zones was proposed; the manufactured prototypes of the designed device were experimentally studied. In the designed photosensor, the ballistic transport of photoelectrons in the vacuum gap with a strong field provides a possibility for the creation of ultra-fast optoelectronic devices, such as modulators, detectors, and generators.

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Section: A Model For the Tunnel Photocurrent Within The Structuresupporting

confidence: 60%

Section: A Model For the Tunnel Photocurrent Within The Structuresupporting

confidence: 60%

Section: Appl Sci 2019 9 X For Peer Review 9 Of 16mentioning

confidence: 99%

Section: Appl Sci 2019 9 X For Peer Review 9 Of 16mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

A Visible and Near-IR Tunnel Photosensor with a Nanoscale Metal Emitter: The Effect of Matching of Hot Electrons Localization Zones and a Strong Electrostatic Field

et al. 2019

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Photofield electron emission from an optical fiber nanotip

Keramati

Passian

Khullar

et al. 2020

Applied Physics Letters

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We demonstrate a nanotip electron source based on a graded index multimode silica optical fiber, tapered at one end to a radius of curvature r ~ 50 nm and coated with a thin film of gold. We report observation of laserinduced electron photoemission at tip bias potentials below the onset of dark field emission (FE). Single-photon photofield emission (PFE) is identified as the emission mechanism, which exhibits fast switching times with an upper limit on the order of 1 μs. The explored fiber optic nanotips are flexible back-illuminated emitters, which can be operated in CW and pulsed modes using lasers with photon energies in the visible range or higher. The mechanical flexibility of the source can facilitate externally controlled positioning. Multiple, individually addressable, nanotips may be assembled into a bundle for applications such as computational electron ghost imaging.Nanotip electron photocathodes have been widely studied in recent years as point-like emitters. This is incentivized by the advances in laser technology, which has enabled joint time-resolved and spatially coherent operation [1][2][3][4][5] . Commonly, a pulsed laser beam is sent into the vacuum chamber hosting the needle source where it is tightly focused onto the nanotip apex 6-8 . This makes the beam alignment on the tip challenging and prone to mechanical vibrations. A few back-illuminated tip sources, for which some strict optical alignment requirements are circumvented, have been realized. For example, a 100-μm-long diamond nanotip needle, back-illuminated with a low-repetition-rate ns laser in the UV range, was shown to photoemit in the short-wavelength (i.e. single-photon absorption) domain 9 . Other works include the demonstration of an optical-fiber-based tungsten (W) (10 nm) nanotip source, in which the employed lowpower continuous-wave (CW) diode laser triggered electron emission, and the significant difference in current rise time (~ 0.01 s) and the fast optical switching time is indicative of thermionic emission 10 . The reported emission was observed in a scanning near-field optical microscopy (SNOM) multimode fiber which constituted a sub-wavelength aperture at its tapered apex. Similarly, a second fiber optic electron source was also studied in which the flat core end-surface of a wide-area fiber was coated with gold (Au)

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Surface plasmon enhanced fast electron emission from metallised fibre optic nanotips

et al. 2020

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Physical mechanisms of electron emission from fibre optic nanotips, namely, tunnelling, multi-photon, and thermionic emission, either prevent fast switching or require intense laser fields. Time-resolved electron emission from nano-sized sources finds applications ranging from material characterisation to fundamental studies of quantum coherence. We present a nano-sized electron source capable of fast-switching (⩽1 ns) that can be driven with low-power femtosecond lasers. The physical mechanism that can explain emission at low laser power is surface plasmon enhanced above-threshold photoemission. An electron emission peak is observed and provides support for resonant plasmonic excitation. The electron source is a metal-coated optical fibre tapered into a nano-sized tip. The fibre is flexible and back illuminated facilitating ease of positioning. The source operates with a few nJ per laser pulse, making this a versatile emitter that enables nanometrology, multisource electron-lithography and scanning probe microscopy.

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Electron emission by long and short wavelength lasers: Essentials for the design of plasmonic photocathodes

Cited by 8 publications

References 43 publications

A Visible and Near-IR Tunnel Photosensor with a Nanoscale Metal Emitter: The Effect of Matching of Hot Electrons Localization Zones and a Strong Electrostatic Field

A Visible and Near-IR Tunnel Photosensor with a Nanoscale Metal Emitter: The Effect of Matching of Hot Electrons Localization Zones and a Strong Electrostatic Field

Photofield electron emission from an optical fiber nanotip

Surface plasmon enhanced fast electron emission from metallised fibre optic nanotips

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