Surface roughness analysis by scanning tunneling microscopy and atomic force microscopy

Files-Sesler, Leigh Ann; Hogan, Tim; Taguchi, Tomoaki

doi:10.1116/1.577723

Cited by 11 publications

(5 citation statements)

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“…Likewise, evaporation onto substrates at a slower rate, approximately 0.5 Å/s, produced a second set of films for comparison (films 2/glass and 2/silicon ). Scanning tunneling microscopy (STM) in air revealed differences in the morphologies of the films deposited at different rates (Figure ): films 1/glass and 1/silicon had smaller average grain sizes than the corresponding samples, 2/glass and 2/silicon 1 STM images of thermally evaporated gold films grown at (a) 1/glass , (b) 1/silicon , (c) 2/glass , and (d) 2/silicon .…”

Section: Resultsmentioning

confidence: 99%

“…We cannot rule out, however, that in some cases differences in the composition of the air (e.g., the concentration of ozone or other oxidants) in contact with the sample may also play a role. We assume that grain boundaries evident in the STM images correspond to defects (e.g., line defects between ordered domains) in the SAMs adsorbed at these sites, and as such, they give rise to enhanced reactivity . In addition, XRD of a gold film evaporated at the faster rate indicated the presence of more Au(100), which binds alkanethiolates less strongly than does Au(111) …”

Section: Discussionmentioning

confidence: 99%

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Air Oxidation of Self-Assembled Monolayers on Polycrystalline Gold: The Role of the Gold Substrate

et al. 1998

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Alkanethiolates in self-assembled monolayers on gold oxidize in air, in the dark, to form sulfinates and sulfonates. The kinetics of oxidation, however, vary depending on the morphology of the underlying gold, with the rate of oxidation increasing dramatically with a decrease in the size of the grains and the amount of Au(111) on the surface. This difference in kinetics of oxidation is sufficiently great that it may provide insight into discrepancies among previous reports in the literature regarding the inertness of these SAMs in air. The oxidized products also desorb readily, and these species decompose under prolonged X-ray irradiation in ultrahigh vacuum.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Air Oxidation of Self-Assembled Monolayers on Polycrystalline Gold: The Role of the Gold Substrate

et al. 1998

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“…164,169,170 The generation of disordered SAMs, which is a direct product of oxidation (be it in the dark or under UV irradiation), is dramatically faster on rough substrates (commonly found on directly evaporated metals) or polycrystalline substrates where the increased number of grains and grain boundaries undermine the stability of SAMs due to the varied binding strength of thiols and chemical reactivity. 171,172 B. Covalent/non-covalent thiol-free anchors…”

Section: Stabilitymentioning

confidence: 99%

Charge transport through molecular ensembles: Recent progress in molecular electronics

Liu¹,

Soni

Qiu³

et al. 2021

Chemical Physics Reviews

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This review focuses on molecular ensemble junctions in which the individual molecules of a monolayer each span two electrodes. This geometry favors quantum mechanical tunneling as the dominant mechanism of charge transport, which translates perturbances on the scale of bond lengths into nonlinear electrical responses. The ability to affect these responses at low voltages and with a variety of inputs, such as de/protonation, photon absorption, isomerization, oxidation/reduction, etc., creates the possibility to fabricate molecule-scale electronic devices that augment; extend; and, in some cases, outperform conventional semiconductor-based electronics. Moreover, these molecular devices, in part, fabricate themselves by defining single-nanometer features with atomic precision via self-assembly. Although these junctions share many properties with single-molecule junctions, they also possess unique properties that present a different set of problems and exhibit unique properties. The primary trade-off of ensemble junctions is complexity for functionality; disordered molecular ensembles are significantly more difficult to model, particularly atomistically, but they are static and can be incorporated into integrated circuits. Progress toward useful functionality has accelerated in recent years, concomitant with deeper scientific insight into the mediation of charge transport by ensembles of molecules and experimental platforms that enable empirical studies to control for defects and artifacts. This review separates junctions by the trade-offs, complexity, and sensitivity of their constituents; the bottom electrode to which the ensembles are anchored and the nature of the anchoring chemistry both chemically and with respect to electronic coupling; the molecular layer and the relationship among electronic structure, mechanism of charge transport, and electrical output; and the top electrode that realizes an individual junction by defining its geometry and a second molecule-electrode interface. Due to growing interest in and accessibility of this interdisciplinary field, there is now sufficient variety in each of these parts to be able to treat them separately. When viewed this way, clear structure-function relationships emerge that can serve as design rules for extracting useful functionality.

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“…Accurate length metrology of sub-micrometer surface features is important for a variety of technologies. Determination of grain size [ 1 ] or surface microroughness [ 2 ] and comparison of measured dimensions of organic molecules to calculated models [ 3 ] all require accuracy on the scale of nanometers or better. The Semiconductor Industry Association has identified critical dimension metrology at this scale as an important item on the path to the next generation of semiconductor electronics [ 4 ].…”

Section: Introductionmentioning

confidence: 99%

Algorithms for scanned probe microscope image simulation, surface reconstruction, and tip estimation

Villarrubia¹

1997

J. Res. Natl. Inst. Stand. Technol.

620

497

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To the extent that tips are not perfectly sharp, images produced by scanned probe microscopies (SPM) such as atomic force microscopy and scanning tunneling microscopy are only approximations of the specimen surface. Tip-induced distortions are significant whenever the specimen contains features with aspect ratios comparable to the tip’s. Treatment of the tip-surface interaction as a simple geometrical exclusion allows calculation of many quantities important for SPM dimensional metrology. Algorithms for many of these are provided here, including the following: (1) calculating an image given a specimen and a tip (dilation), (2) reconstructing the specimen surface given its image and the tip (erosion), (3) reconstructing the tip shape from the image of a known “tip characterizer” (erosion again), and (4) estimating the tip shape from an image of an unknown tip characterizer (blind reconstruction). Blind reconstruction, previously demonstrated only for simulated noiseless images, is here extended to images with noise or other experimental artifacts. The main body of the paper serves as a programmer’s and user’s guide. It includes theoretical background for all of the algorithms, detailed discussion of some algorithmic problems of interest to programmers, and practical recommendations for users.

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Surface roughness analysis by scanning tunneling microscopy and atomic force microscopy

Cited by 11 publications

References 0 publications

Air Oxidation of Self-Assembled Monolayers on Polycrystalline Gold: The Role of the Gold Substrate

Air Oxidation of Self-Assembled Monolayers on Polycrystalline Gold: The Role of the Gold Substrate

Charge transport through molecular ensembles: Recent progress in molecular electronics

Algorithms for scanned probe microscope image simulation, surface reconstruction, and tip estimation

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