Identifying passivated dynamic force microscopy tips on H:Si(100)

Sharp, Peter; Jarvis, Samuel; Woolley, Richard A. J.; Sweetman, Adam; Kantorovich, Lev; Pakes, C. I.; Moriarty, Philip

doi:10.1063/1.4726086

Cited by 24 publications

(24 citation statements)

References 31 publications

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“…On the adatoms we see a strong attractive force, with a peak attraction of ∼2 nN. In the data acquired with the repulsive adatom contrast, we see a similar interaction over the molecule (peak force ∼100 to 150 pN), but an extremely weak interaction with the adatoms (∼10 to 50 pN), strongly suggesting a passivated tip [30][31][32].…”

Section: B Force Spectra and Tip Characterizationmentioning

confidence: 78%

“…Fixed tip atoms are grayed out while surface atoms which are free to relax are shaded in green. which observed that H or OH tip terminations suppress the chemical attraction [30,32]. Both of these tips are passivated, and, by analogy to the imaging mechanism described for CO-terminated metal tips [1], are likely to be able to produce submolecular contrast while also resulting in repulsive contrast on the silicon adatoms.…”

Section: Repulsive-type Tipsmentioning

confidence: 88%

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Intramolecular bonds resolved on a semiconductor surface

et al. 2014

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Noncontact atomic force microscopy (NC-AFM) is now routinely capable of obtaining submolecular resolution, readily resolving the carbon backbone structure of planar organic molecules adsorbed on metal substrates. Here we show that the same resolution may also be obtained for molecules adsorbed on a reactive semiconducting substrate. Surprisingly, this resolution is routinely obtained without the need for deliberate tip functionalization. Intriguingly, we observe two chemically distinct apex types capable of submolecular imaging. We characterize our tip apices by "inverse imaging" of the silicon adatoms of the Si(111) −7×7 surface and support our findings with detailed density functional theory (DFT) calculations. We also show that intramolecular resolution on individual molecules may be readily obtained at 78 K, rather than solely at 5 K as previously demonstrated. Our results suggest a wide range of tips may be capable of producing intramolecular contrast for molecules adsorbed on semiconductor surfaces, leading to a much broader applicability for submolecular imaging protocols.

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Section: B Force Spectra and Tip Characterizationmentioning

confidence: 78%

Section: Repulsive-type Tipsmentioning

confidence: 88%

Intramolecular bonds resolved on a semiconductor surface

et al. 2014

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“…2(a)]. The imaging, and large peak attractive forces, show that the tip is not passivated by CO or OH, since this would result in inverted imaging of the adatoms, and/or peak tip-sample tip-adatom forces of the order of ∼100 pN [31][32][33]. The combination of STM and NC-AFM characterization consequently strongly suggests a silicon-terminated tip apex, particularly in light of the data presented in Fig.…”

Section: Resultsmentioning

confidence: 99%

Measuring the reactivity of a silicon-terminated probe

Sweetman

Stirling²,

Jarvis

et al. 2016

Phys. Rev. B

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It is generally accepted that the exposed surfaces of silicon crystals are highly reactive due to the dangling bonds which protrude into the vacuum. However, surface reconstruction not only modifies the reactivity of bulk silicon crystals, but also plays a key role in determining the properties of silicon nanocrystals. In this study we probe the reactivity of silicon clusters at the end of a scanning probe tip by examining their interaction with closed-shell fullerene molecules. Counter to intuitive expectations, many silicon clusters do not react strongly with the fullerene cage, and we find that only specific highly oriented clusters have sufficient reactivity to break open the existing carbon-carbon bonds.

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“…Oxide-covered Si tips were proposed to explain the images of Si(111)-(7×7) exhibiting such weak corrugation. The influence of the tip chemical reactivity in the particular case of the semiconductor Si(100) surface was recently studied by Sharp et al 20 Furthermore, Jarvis et al 21 investigated the role of the orbital alignment between the tip and hydrogen-passivated Si(100) surface in the atom manipulation process based on the atomic exchange mechanism.…”

Section: Introductionmentioning

confidence: 99%

Force mapping on a partially H-covered Si(111)-(7×7) surface: Influence of tip and surface reactivity

et al. 2013

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We report force mapping experiments on Si(111)-(7×7) surfaces with adsorbed hydrogen, using atomic force microscopy at room temperature supported by density functional theory (DFT) simulations. On the basis of noncontact atomic force microscopy (NC-AFM) images as well as force versus distance curves measured over both hydrogen-passivated and bare Si adatoms, we identified two types of tip termination, which result in different modes of interaction with the surface. The statistics of the tip dependence of the measured forces, which are effectuated using various tip states with different cantilevers, reveal the typical values of the force and their distribution in the two characteristic interaction modes. The experimental results are corroborated by DFT calculations performed for different tip structures. As a reactive tip, the dimer-terminated Si tip yields results in satisfactory agreement with experimental force curves for hydrogen-passivated and nonpassivated Si adatom sites. An oxidized Si dimer tip that bears a hydroxyl group on its apex reproduces well the experimental force curves acquired by nonreactive tips. This tip model could thus be used to interpret the experimentally obtained weak image contrast for the Si(111)-(7×7) surface. The forces are thought to arise as a result of a weak electrostatic interaction involving a permanent dipole at the tip apex enhanced by the charge density redistribution due to the interaction with surface adatoms.

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Identifying passivated dynamic force microscopy tips on H:Si(100)

Cited by 24 publications

References 31 publications

Intramolecular bonds resolved on a semiconductor surface

Intramolecular bonds resolved on a semiconductor surface

Measuring the reactivity of a silicon-terminated probe

Force mapping on a partially H-covered Si(111)-(7×7) surface: Influence of tip and surface reactivity

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