Dependence of the chromatic aberration spot size on the form of the energy distribution of the charged particles

Barth, J.; Nykerk, M. David

doi:10.1016/s0168-9002(98)01531-9

Cited by 21 publications

(4 citation statements)

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“…13,14 Analysis of the shape of the intrinsic TED curves for both the CFE ͑ = 4.3 eV͒ and SE ͑ = 2.8 eV͒ regimes gave the following relationships between the FW50 and FWHM: FW50 SE ͑int.͒Ϸ0.60 FWHM SE ͑int.͒ and FW50 CFE ͑int.͒Ϸ0.72 FWHM CFE ͑int.͒. Thus, for the SE cathode with a = 550 nm, J =2ϫ 10 7 A/m 2 , and m = 0.2, one obtains IЈ ϳ 150 A / sr. For electron optical analysis the full width of the TED containing 50% of the current ͑FW50͒ is a more useful quantity.…”

Section: A Energy Distributionmentioning

confidence: 99%

Comparison of parameters for Schottky and cold field emission sources

Schwind¹,

Magera²,

Swanson³

2006

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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Relationship between field emission property and composition of carbon nanotube paste for large area cold cathode J.Total energy distribution ͑TED͒ measurements were carried out for point electron sources operating in the cold field ͑T = 300 K͒ and Schottky ͑T = 1800 K͒ emission regimes. The full width at half maximum ͑FWHM͒ values of the TED's for both emission regimes were found to increase significantly above the respective theoretical values as the emitter radius ͑a͒ was decreased and as the angular current density ͑IЈ͒ was increased. This increase in the FWHM arises from the stochastic electron-electron interactions in the beam commonly known as the Boersch ͓Z. Phys. 139, 115 ͑1954͔͒ effect. A method was devised to extract the magnitude of the Boersch effect from the experimental TED's. The TED's were investigated as a function of IЈ and a. In addition, the reduced brightness for both emitters was calculated from the virtual source size and IЈ values as a function of the FWHM values.

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Section: A Energy Distributionmentioning

confidence: 99%

Comparison of parameters for Schottky and cold field emission sources

Schwind¹,

Magera²,

Swanson³

2006

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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“…Because the main interest is the effect of the choices in operating conditions and tip geometry on the contribution from chromatic aberration, the fitted FWHM and 1/p values of the bell curve are converted into a FW50 value. The FW50 value is directly proportional to the chromatic aberration, independent of the shape of the distribution, unlike the FWHM [Bar99]. For a Schottky emitter in normal operation it turns out that the FW50 of an energy distribution is ~ 0.6-0.7·FWHM depending on the conditions.…”

Section: Fit Resultsmentioning

confidence: 99%

Physics of Schottky Electron Sources

Bronsgeest¹

2016

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“…In that case, it is convenient that the FW50 of the chromatic aberration contribution, contrary to, e.g., the FWHM, is approximately independent of the shape of the energy distribution. 10 Also, for electron probes, the inevitable diffraction contribution ͓the intensity distribution produced by Fraunhofer diffraction around a circular aperture ͑Airy pattern͔͒, has a FW50 width that is very close to its FWHM ͑4% difference͒.…”

Section: Defining Sizementioning

confidence: 99%

Probe current, probe size, and the practical brightness for probe forming systems

Bronsgeest¹,

Barth²,

Swanson³

et al. 2008

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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Probe size, shape, and current are important parameters for the performance of all probe forming systems such as the scanning ͑transmission͒ electron microscope, the focused ion beam microscope, and the Gaussian electron beam lithography system. Currently, however, the relation between probe current and probe size is ill defined. The key lies in a lacking definition of "size." This problem is solved with the introduction of the "practical brightness." In literature, many different definitions of "brightness" can be found, but for systems in which the whole of the virtual source is imaged onto the target, it is the practical brightness of a source that determines how much current is in the probe. This means that only with the practical brightness the performance of a probe forming system can be calculated quantitatively. The beauty of the practical brightness is that this source property is unaffected by the quality of the column: without interactions between electrons in the beam, the practical brightness is conserved down to the target. This makes it the only relevant brightness for probe forming systems to be used to compare different sources. The practical brightness can be measured, but can also be calculated when the source intensity profile is known. The Gaussian source intensity profile of thermionic, Schottky, and cold field emitters yields a practical brightness of 1.44ej / ͗͘, where j is the current density on the emitting surface and ͗͘ is the average tangential electron energy.

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Dependence of the chromatic aberration spot size on the form of the energy distribution of the charged particles

Cited by 21 publications

References 1 publication

Comparison of parameters for Schottky and cold field emission sources

Comparison of parameters for Schottky and cold field emission sources

Physics of Schottky Electron Sources

Probe current, probe size, and the practical brightness for probe forming systems

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