Nanoscale imaging of mobile carriers and trapped charges in delta doped silicon p–n junctions

Gramse, Georg; Kölker, Alexander; Škereň, Tomáš; Stock, Taylor J. Z.; Aeppli, G.; Kienberger, Ferry; Fuhrer, Andreas; Curson, Neil J.

doi:10.1038/s41928-020-0450-8

Cited by 28 publications

(33 citation statements)

References 43 publications

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“…It is worth noting that materials with even small conductivities appear as "metallic" for such low frequencies. In some specific setups, and by using the heterodyne detection method, very large frequencies, beyond the dielectric relaxation frequency of the material (typically in the GHz range) can be also considered (Gramse et al, 2020). In these cases, the modeling needs to include explicitly the conductivity effects.…”

Section: Methodsmentioning

confidence: 99%

“…In this case, materials will appear as "metallic" only when they display a significant conductivity. We do not consider this case in the present work (see, for instance, Gramse et al, 2020). In the quantitative analysis, first the tip geometry is determined from electric force measurements made on a bare part of the conducting substrate by comparing them with the corresponding theoretically calculated electric forces, with the tip radius and half cone angle as fitting parameters.…”

Section: Methodsmentioning

confidence: 99%

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Spatial Resolution and Capacitive Coupling in the Characterization of Nanowire Nanocomposites by Scanning Dielectric Microscopy

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Spatial Resolution and Capacitive Coupling in the Characterization of Nanowire Nanocomposites by Scanning Dielectric Microscopy

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“…Thus, a balance must be achieved for the realization of the experiments between preserving cell structure and being able to measure its dielectric properties with in-liquid SDM. Typically, using the experimental setup we implemented for this work, allows to reach the 10-100 MHz frequency range of applied electric voltage, and considering other similar implementations one can even reach the GHz range if a refinement of the electric shielding circuitry is carried out [54]. This experimental limitation sets a limit for the molarity of the solution to be used, which for our case is in the order of 10-20 mM range (this number depends also on the chemical composition of the solute), but could possibly be extended to 100's mM if the GHz frequencies are used.…”

Section: 1402 8 Of 13mentioning

confidence: 99%

Dielectric Imaging of Fixed HeLa Cells by In-Liquid Scanning Dielectric Force Volume Microscopy

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Mapping the dielectric properties of cells with nanoscale spatial resolution can be an important tool in nanomedicine and nanotoxicity analysis, which can complement structural and mechanical nanoscale measurements. Recently we have shown that dielectric constant maps can be obtained on dried fixed cells in air environment by means of scanning dielectric force volume microscopy. Here, we demonstrate that such measurements can also be performed in the much more challenging case of fixed cells in liquid environment. Performing the measurements in liquid media contributes to preserve better the structure of the fixed cells, while also enabling accessing the local dielectric properties under fully hydrated conditions. The results shown in this work pave the way to address the nanoscale dielectric imaging of living cells, for which still further developments are required, as discussed here.

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“…We apply high-frequency techniques operating at a few GHz, where the admittance of the capacitance scales linearly with the frequency. The exceptionally high sensitivity of GHz admittance measurements combined with the advantages of nearfield detection in microwave microscopy has recently enabled breakthroughs in diverse areas of research, including semiconductor physics, [29,30] molecular electronics, [21] biophysics, [31] and energy materials. [32] To the best of our knowledge, the direct measurements of electrochemical charge transfer by microwave microscopy-reported herein-have not been reported previously.…”

Section: Introductionmentioning

confidence: 99%

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to batteries. [6] Additionally, it allows us to increase our understanding of molecular interactions in liquid, which is currently based on theoretical models of ensemble measurements. Towards these goals, scanning electrochemical microscopy (SECM), including the use of nanopipettes, [7][8][9] has been developed to sense electrochemical reactions locally, providing spatial resolution of typically μm to the sub-μm range, [10][11][12] but also fast reactions on nanometric particles could be resolved when well isolated. [13,14] SECM techniques are now well-established for probing electrochemical systems at the micro-and nanoscale levels. [15,16] Scanning probes have exploited redox-cycling amplification to reduce the electrode dimensions while keeping a reasonable signal level. [11,17,18] Electrochemical scanning tunneling microscopy (EC-STM) has been used to study electrochemistry indirectly from a molecular electronics perspective. [19,20] To date, these techniques have enabled measurements down to the fA (10 −15 Ampere) range, [11,[21][22][23][24][25] which is still not sensitive enough to obtain electrochemical signals at the nanoscale, except in the specific case of redox cycling amplification when ferrocene (Fc) is confined between 2 neighboring electrodes at the nanoscale. [23,25] For the versatile measurement of electrochemical currents at the nanoscale aA (10 −18 Ampere) sensitivity is crucial.Electrochemical microscopy techniques have extended the understanding of surface chemistry to the micrometer and even sub-micrometer level. However, fundamental questions related to charge transport at the solidelectrolyte interface, such as catalytic reactions or operation of individual ion channels, require improved spatial resolutions down to the nanoscale. A prerequisite for single-molecule electrochemical sensitivity is the reliable detection of a few electrons per second, that is, currents in the atto-Ampere (10 −18 A) range, 1000 times below today's electrochemical microscopes. This work reports local cyclic voltammetry (CV) measurements at the solid-liquid interface on ferrocene self-assembled monolayer (SAM) with sub-atto-Ampere sensitivity and simultaneous spatial resolution < 80 nm. Such sensitivity is obtained through measurements of the charging of the local faradaic interface capacitance at GHz frequencies. Nanometer-scale details of different molecular organizations with a 19% packing density difference are resolved, with an extremely small dispersion of the molecular electrical properties. This is predicted previously based on weak electrostatic interactions between neighboring redox molecules in a SAM configuration. These results open new perspectives for nano-electrochemistry like the study of quantum mechanical resonance in complex molecules and a wide range of applications from electrochemical catalysis to biophysics.

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Nanoscale imaging of mobile carriers and trapped charges in delta doped silicon p–n junctions

Cited by 28 publications

References 43 publications

Spatial Resolution and Capacitive Coupling in the Characterization of Nanowire Nanocomposites by Scanning Dielectric Microscopy

Spatial Resolution and Capacitive Coupling in the Characterization of Nanowire Nanocomposites by Scanning Dielectric Microscopy

Dielectric Imaging of Fixed HeLa Cells by In-Liquid Scanning Dielectric Force Volume Microscopy

Attoampere Nanoelectrochemistry

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