Doping profile of InP nanowires directly imaged by photoemission electron microscopy

Hjort, Martin; Wallentin, Jesper; Timm, Rainer; Zakharov, Alexei; Andersen, Jesper N; Samuelson, Lars; Borgström, Magnus T.; Mikkelsen, Anders

doi:10.1063/1.3662933

Cited by 17 publications

(22 citation statements)

References 29 publications

(20 reference statements)

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“…The point-projection microscopy image is therefore primarily a measure of the electrostatic near-field rather than a shadow image of the geometric structure of the nanoobject. In particular, the point-projection image is sensitive to the doping profile in nanowires [3,50]. Figure 4 b) compares PPM images of a NW recorded in DC field emission mode without laser (top) and SPPdriven mode (bottom) with the same tip-sample distance d = 14 µm, corresponding to a geometric magnification of M ≈ 7000.…”

Section: Resultsmentioning

confidence: 99%

Nanofocused Plasmon-Driven Sub-10 fs Electron Point Source

et al. 2016

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Progress in ultrafast electron microscopy relies on the development of efficient laser-driven electron sources delivering femtosecond electron pulses to the sample. In particular, recent advances employ photoemission from metal nanotips as coherent point-like femtosecond low-energy electron sources. We report the nonlinear emission of ultrashort electron wave packets from a gold nanotip generated by nonlocal excitation and nanofocusing of surface plasmon polaritons. We verify the nanoscale localization of plasmon-induced electron emission by its electrostatic collimation characteristics. With a plasmon polariton pulse duration below 8 fs at the apex, we identify multiphoton photoemission as the underlying emission process. The quantum efficiency of the plasmon-induced emission exceeds that of photoemission from direct apex illumination. We demonstrate the application for plasmon-triggered point-projection imaging of an individual semiconductor nanowire at 3 µm tip-sample distance. Based on numerical simulations we estimate an electron pulse duration at the sample below 10 fs for tip-sample distances up to few micrometers. Plasmon-driven nanolocalized electron emission thus enables femtosecond point-projection microscopy with unprecedented temporal and spatial resolution, femtosecond low-energy electron in-line holography, and opens a new route towards femtosecond scanning tunneling microscopy and spectroscopy.

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Section: Resultsmentioning

confidence: 99%

Nanofocused Plasmon-Driven Sub-10 fs Electron Point Source

et al. 2016

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“…thick Au seeded InP nanowires with an undoped (nominally intrinsic) segment sandwiched between highly sulfur doped n-type segments [52]. The nanowires can be characterized both using directly emitted photoelectrons from specific core levels and SEs from inelastic scattering inside the sample.…”

Section: Xuv Imagingmentioning

confidence: 99%

“…Owing to signal intensity and photon energy PEEM imaging used all of the emitted electrons and thus primarily SEs. The preceding example and many other works clearly show that SEs can give much information about structural [54], chemical [52], and magnetic properties [55] with nanoscale resolution. SEs are thus in principle an excellent source of information; however, as with electrons emitted via the Hg lamp, since several different phenomena play a role in determining the SE intensity, interpreting and predicting how a given sample will display in SEs can be tricky.…”

Section: Xuv Imagingmentioning

confidence: 99%

Imaging Localized Surface Plasmons by Femtosecond to Attosecond Time‐Resolved Photoelectron Emission Microscopy – “ATTO‐PEEM”

Chew

Pearce

Scheffold

et al. 2014

Attosecond Nanophysics

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The direct detection of the spatiotemporal dynamics of nanolocalized optical near-fields on nanostructured metal surfaces, for example, imaging of localized surface plasmons (cf. Chapter 1) on rough or nanostructured metal films or the imaging of propagating surface plasmon polaritons at a vacuum-metal or metal-dielectric interface is a prerequisite to further control and optimize surface-plasmon based ultrafast nanooptics for future device development and applications [1][2][3][4].While free electrons in metals collectively respond to excitation from a light pulse, which is resonant to the surface plasmon frequency of the system, and squeeze and amplify the field intensity of the incoming plane light field into a subwavelength spatial volume, the typically broad frequency bandwidth of surface plasmon resonances supports an ultrafast response of these fields with rapid field changes on sub-femtosecond time scales [5].The sub-wavelength nanoscaled localization of optical fields in the vicinity of metal nanostructures and the ultrafast temporal evolution of such fields on a 0.1-100 fs time scale require the invention and development of new experimental methodologies, which combine nanometer (sub-optical) spatial resolution, sub-femtosecond temporal resolution, and optionally further nanospectroscopic information.Resolving the spatial distribution of such fields requires a microscopic technique with sub-optical spatial resolution, for example, in the 10-100 nm range. Scanning near-field optical microscopy (SNOM) techniques have been successfully applied with spatial resolutions of about ∼100 nm; however, the combination with ultrashort light pulses is still very difficult. Photoemission electron microscopy (PEEM) is a technique capable of resolving the spatial emission distribution of photoelectrons with an ultimate resolution of ∼10 nm.

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“…We show in this paper that XPEEM can provide a direct insight on this issue. Although XPEEM was already employed to study individual semiconducting wires including Si [7], InP [8][9][10] and GaAs [11], this kind of analysis still remains scarce because of the intrinsic difficulty to work on individual objects having a pronounced topography. Here, a direct quantification of electrically-active dopants in highly conductive GaN wires, is provided by combining XPEEM and Scanning Auger Microscopy in reasonable agreement with electrical results.…”

Section: Introductionmentioning

confidence: 99%