Characterization of nanowires with the low energy electron point source (LEEPS) microscope

Beyer, André; Weber, Dirk Henning; Völkel, B.

doi:10.1002/pssb.201046260

Cited by 4 publications

(3 citation statements)

References 43 publications

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“…An elegant way of realising imaging with a coherent electron beam is via in-line Gabor holography [22][23] (also called point-projection imaging [24]), which does not require any lenses, and thus is free of aberrations. With invention of very sharp and bright tips [9], inline holograms with rich interference patterns became available [14,[25][26], and objects reconstructed at the nanometre resolution from their holograms were reported [20,[27][28][29][30][31][32][33][34][35][36][37][38][39][40].…”

Section: Effect Of Source Size On Resolutionmentioning

confidence: 99%

Spatial coherence of electron beams from field emitters and its effect on the resolution of imaged objects

Latychevskaia

2017

Ultramicroscopy

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Sub-nanometer and nanometer-sized tips provide high coherence electron sources.Conventionally, the effective source size is estimated from the extent of the experimental biprism interference pattern created on the detector by applying the van Cittert Zernike theorem. Previously reported experimental intensity distributions on the detector exhibit Gaussian distribution and our simulations show that this is an indication that such electron sources must be at least partially coherent. This, in turn means that strictly speaking the Van Cittert Zernike theorem cannot be applied, since it assumes an incoherent source. The approach of applying the van Cittert Zernike theorem is examined in more detail by performing simulations of interference patterns for the electron sources of different size and different coherence length, evaluating the effective source size from the extent of the simulated interference pattern and comparing the obtained result with the pre-defined value.The intensity distribution of the source is assumed to be Gaussian distributed, as it is observed in experiments. The visibility or the contrast in the simulated holograms is found to be always less than 1 which agrees well with previously reported experimental results and thus can be explained solely by the Gaussian intensity distribution of the source. The effective source size estimated from the extent of the interference pattern turns out to be of about 2-3 times larger than the pre-defined size, but it is approximately equal to the intrinsic resolution of the imaging system. A simple formula for estimating the intrinsic resolution, which could be useful when employing nano-tips in in-line Gabor holography or point-projection microscopy, is provided.

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Section: Effect Of Source Size On Resolutionmentioning

confidence: 99%

Spatial coherence of electron beams from field emitters and its effect on the resolution of imaged objects

Latychevskaia

2017

Ultramicroscopy

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“…Thus, the same experimental setup can be utilized in two regimes, since at shorter source-to-sample distances, an interference pattern emerges and a point projection image turns into a hologram. This is why this experimental arrangement is referred to by some researchers as PPM [28][29][30][31][32][33][34][35][36], and by others as in-line holography [37,38]. Another point which should be mentioned is that in the in-line holography proposed by Gabor, the point source is a focused spot, rather than a physical source as in PPM.…”

Section: Point Projection Microscopy (Ppm)mentioning

confidence: 99%

Holography and Coherent Diffraction Imaging with Low-(30–250 eV) and High-(80–300 keV) Energy Electrons: History, Principles, and Recent Trends

Latychevskaia

2020

Materials

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In this paper, we present the theoretical background to electron scattering in an atomic potential and the differences between low- and high-energy electrons interacting with matter. We discuss several interferometric techniques that can be realized with low- and high-energy electrons and which can be applied to the imaging of non-crystalline samples and individual macromolecules, including in-line holography, point projection microscopy, off-axis holography, and coherent diffraction imaging. The advantages of using low- and high-energy electrons for particular experiments are examined, and experimental schemes for holography and coherent diffraction imaging are compared.

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“…CS‐AFM with its small (metal tip < NW diameter) and maneuverable probe is quite suitable for studying the electrical transport at metal‐semiconductor contact (MSC). This is in contrast to studying the I – V characteristics of VA‐ZnO NWs by low energy electron point source (LEEPS) microscopy , which does not work on the principle of a direct contact.…”

Section: Introductionmentioning

confidence: 99%

Electrical contact fabrication on vertically aligned ZnO nanowires investigated by current sensing AFM

Jain

Kushto

Wolak

et al. 2013

Physica Status Solidi (a)

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We present a simple method for generating vertically aligned (VA) ZnO nanowire (NW) arrays with tailored electrical top contacts, suitable for photodetector and photovoltaic applications. ZnO NWs were synthesized on Si substrate in house using a hydro-thermal method, producing dense and highly organized vertical ZnO NW ($50-100 nm) arrays. The vertical geometry of the NW arrays facilitated further processing of the NW structures and streamlined in situ characterization of individual NWs as well as entire NW ensembles. The top contact metallization involved depositing a thin film of low work function metals such as aluminum (5 nm) followed by a thin film of gold (15 nm) onto NW arrays, partially embedded in an insulating silsesquioxane-based material (SOG-400F). The I-V characteristics of individual ZnO NWs were measured using current sensing atomic force microscopy (CS-AFM). Compared with arrays of as-grown ZnO NWs, the metalized top contacts of NWs resulted in improved I-V characteristics with good Ohmic behavior at the metal-semiconductor contact (MSC).

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Characterization of nanowires with the low energy electron point source (LEEPS) microscope

Cited by 4 publications

References 43 publications

Spatial coherence of electron beams from field emitters and its effect on the resolution of imaged objects

Spatial coherence of electron beams from field emitters and its effect on the resolution of imaged objects

Holography and Coherent Diffraction Imaging with Low-(30–250 eV) and High-(80–300 keV) Energy Electrons: History, Principles, and Recent Trends

Electrical contact fabrication on vertically aligned ZnO nanowires investigated by current sensing AFM

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