The influence of preadsorbed K on the adsorption of PF3 on Ru(0001) studied by soft x-ray photoelectron spectroscopy

Chakarian, V.; Shuh, David K.; Yarmoff, J. A.; Tao, H.-S.; Diebold, Ulrike; Maschhoff, Brian L.; Madey, Theodore E.; Shinn, Neal D.

doi:10.1063/1.467195

Cited by 7 publications

(3 citation statements)

References 34 publications

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“…We assume that the work func-tion of clean Ru͑0001͒ is about 5.52 eV. 20 Chemisorption of ϳ1 ML PF 3 increases the work function about 0.5 eV. Adsorption of H 2 O on the PF 3 /Ru͑0001͒ surface leads to a decrease in the work function.…”

Section: Work Function Measurementsmentioning

confidence: 99%

Low energy (<5 eV) F+ and F− ion transmission through condensed layers of water

Akbulut

Madey

Nordlander

1997

The Journal of Chemical Physics

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Development of a triplasmatron ion source for the generation of SF 5 + and F − primary ion beams on an ion microscope secondary ion mass spectrometry instrumentWe report on the transmission of F ϩ and F Ϫ ions through ultrathin films of condensed water at 20 K, and compare the experimental results with theoretical calculations. The F ϩ and F Ϫ ions are produced by ESD ͑electron stimulated desorption͒ of a PF 3 monolayer adsorbed on a Ru͑0001͒ surface ͑PF 3 /Ru͑0001͒ surface͒. We find two surprising results: ͑a͒ the off-normal F ϩ signal is attenuated to ϳ1% by only ϳ2.5 monolayer ͑ML͒ of H 2 O, while a much thicker layer, ϳ10 ML of H 2 O, is necessary for equivalent attenuation of the F Ϫ ion emission, and ͑b͒ 1 ML of H 2 O increases the emission of F Ϫ ions and causes a dramatic change in the ion angular distribution. The striking changes in the angular distribution of F Ϫ ions transmitted through condensed H 2 O films indicate that elastic scattering is an important process in determining the attenuation of F Ϫ by H 2 O. No direct evidence for any kind of ion-molecule chemical reaction or collision induced dissociation reaction has been found. The strong attenuation of F ϩ without substantial changes in angular distribution suggests that charge transfer processes are important in limiting the transmission of F ϩ ions. Our quantum mechanical calculations indicate that the increase in F Ϫ emission upon adsorption of р1 ML of H 2 O is mainly due to a decrease in the neutralization probability of F Ϫ with the substrate, by a dielectric screening mechanism. The calculations also show that the increase in the F Ϫ survival probability saturates after a water bilayer ͑1 ML H 2 O͒ is formed, which is in excellent agreement with the experiment. Our measurements show no evidence for diffusion of H 2 O on the PF 3 /Ru͑0001͒ surface between 20 and 60 K; the lack of diffusion, together with exponential attenuation of F ϩ and F Ϫ with H 2 O thickness, indicates that H 2 O vapor condensed on the PF 3 /Ru͑0001͒ surface at 20 K grows statistically.

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Section: Work Function Measurementsmentioning

confidence: 99%

Low energy (<5 eV) F+ and F− ion transmission through condensed layers of water

Akbulut

Madey

Nordlander

1997

The Journal of Chemical Physics

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“…In the case of pristine BP, a broad peak located at 134.5 eV was observed, which belongs to oxidized phosphorus (P x O y ) owing to the inevitable slight oxidation when the BP was prepared on SiO 2 in air within 1 h. Nevertheless, in the case of BP with PFSA passivation, the P x O y peak was significantly inhibited due to the formation of nonreactive P–F bonds at the interface of BP and PFSA. Feature peaks were observed in the P 2p spectra at approximately 132.7, 133.7, 135.1, and 136.9 eV, confirming the formation of P–F covalent bonds through fluorination. , Moreover, it was calculated ∼41.1% fluorination from the integrated area ratio of P–F peaks divided by the total area of the spectra. Additionally, the protective capability of PFSA was further evaluated by accelerated degradation testing, where the samples were loaded into a chamber for a harsh environmental test (under boiling water at 150 °C for 15 min).…”

Section: Resultsmentioning

confidence: 83%

“…Feature peaks were observed in the P 2p spectra at approximately 132.7, 133.7, 135.1, and 136.9 eV, confirming the formation of P−F covalent bonds through fluorination. 55,66 Moreover, it was calculated ∼41.1% fluorination from the integrated area ratio of P−F peaks divided by the total area of the spectra. Additionally, the protective capability of PFSA was further evaluated by accelerated degradation testing, where the samples were loaded into a chamber for a harsh environmental test (under boiling water at 150 °C for 15 min).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

In Situ Cleaning and Fluorination of Black Phosphorus for Enhanced Performance of Transistors with High Stability

Hsieh

Huang

et al. 2020

ACS Appl. Mater. Interfaces

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Most two-dimensional (2D) semiconductors suffer from intrinsic instability under ambient conditions, especially 2D black phosphorus (BP). Although much effort has been made to study the passivation of 2D materials against corrosion by oxygen and water molecules, facile and effective passivation with long-term stability is still challenging; in particular, selective passivation, which is critical for integration into nanoelectronics, is still lacking. Here, we develop a novel passivation route for BP using a fluorinated self-assembled thin film of PFSA (perfluorosulfonic acid, PFSA), where the surface modifier with high hydrophobicity on BP presents extremely stable characteristics over five months under ambient conditions. Moreover, we report for the first time in situ cleaning and selective fluorination of only BP flakes on a SiO2/Si substrate by a spin-coating process followed by ultrasonication, which was attributed to the formation of P–F covalent bonds on the BP surface. Selectively fluorinated BP shows not only enhanced stability in air but also electrical properties of the BP field-effect transistor (FET), with the on-current of the BP FET increasing and presenting enhanced carrier mobility (125 cm2 V–1 s–1) and on/off ratio (104). This significant finding sheds light on fabricating vertical 2D heterostructures to realize high performance and reliability with versatile 2D materials. This work demonstrates an emerging passivation approach for long-term stability together with superior electrical properties, which paves the way for integrating 2D semiconductors into critical channel materials in FETs that are favorable for next-generation digital logic circuits.

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Fluorination‐Enhanced Ambient Stability and Electronic Tolerance of Black Phosphorus Quantum Dots

et al. 2018

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The environmental instability and uneliminable electronic trap states in black phosphorus quantum dots (BPQDs) limit the optoelectronics and related applications of BPQDs. Here, fluorinated BPQDs (F‐BPQDs) are successfully synthesized by using a facile electrochemical exfoliation and synchronous fluorination method. The F‐BPQDs exhibit robust ambient stability and limited fluorination capability, showing a nonstoichiometric fluorination degree (D F) maximum of ≈0.68. Density functional theory calculations confirm that due to the edge etching effect of fluorine adatoms, the simulated F‐BPQDs become structurally unstable when D F surpasses the limit. Furthermore, the trap states of BPQDs can be effectively eliminated via fluorination to obtain a coordination number of 3 or 5 for fluorinated and unfluorinated phosphorus atoms. The results reveal that the air‐stable F‐BPQDs exhibit fluorine defect‐enhanced electronic tolerance, which is crucial for nanophotonics and nanoelectronics applications.

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The influence of preadsorbed K on the adsorption of PF3 on Ru(0001) studied by soft x-ray photoelectron spectroscopy

Abstract: The soft xray photochemistry of physisorbed SiF4. I. Reactions of the molecular species through desorption and dissociation

Cited by 7 publications

References 34 publications

Low energy (<5 eV) F+ and F− ion transmission through condensed layers of water

Low energy (<5 eV) F+ and F− ion transmission through condensed layers of water

In Situ Cleaning and Fluorination of Black Phosphorus for Enhanced Performance of Transistors with High Stability

Fluorination‐Enhanced Ambient Stability and Electronic Tolerance of Black Phosphorus Quantum Dots

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The influence of preadsorbed K on the adsorption of PF3 on Ru(0001) studied by soft x-ray photoelectron spectroscopy

Abstract: The soft xray photochemistry of physisorbed SiF4. I. Reactions of the molecular species through desorption and dissociation

Cited by 7 publications

References 34 publications

Low energy (&lt;5 eV) F+ and F− ion transmission through condensed layers of water

Low energy (&lt;5 eV) F+ and F− ion transmission through condensed layers of water

In Situ Cleaning and Fluorination of Black Phosphorus for Enhanced Performance of Transistors with High Stability

Fluorination‐Enhanced Ambient Stability and Electronic Tolerance of Black Phosphorus Quantum Dots

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Low energy (<5 eV) F+ and F− ion transmission through condensed layers of water

Low energy (<5 eV) F+ and F− ion transmission through condensed layers of water