Possibility of direct exchange diffusion of hydrogen on the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mtext>Cl</mml:mtext><mml:mo>/</mml:mo><mml:mtext>Si</mml:mtext><mml:mrow><mml:mo>(</mml:mo><mml:mrow><mml:mn>100</mml:mn></mml:mrow><mml:mo>)</mml:mo></mml:mrow><mml:mtext>−</mml:mtext><mml:mn>2</mml:mn><mml:mo>×</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:math>surface

Hsieh, Ming‐Feng; Lin, Deng-Sung; Tsay, Shiow-Fon

doi:10.1103/physrevb.80.045304

Cited by 8 publications

(4 citation statements)

References 37 publications

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“…The individual stability of each Si passivation layer shown here (H, Cl, Br, and I) poses an interesting solution to APAM pattern preservation outside of UHV environments when taken in concert with past demonstrations of halogen adsorption into dangling bond structures formed on H-Si [14,41,42]. Figure 4 demonstrates this concept with a sequentially patterned and halogen-exposed H-Si sample that resulted in a complementary resist of multiple, distinct halogen-passivated regions on an otherwise fully H-passivated surface.…”

Section: Co-passivation For Pattern Preservationmentioning

confidence: 70%

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The stability of Cl-, Br-, and I-passivated Si(100)-(2 × 1) in ambient environments for atomically-precise pattern preservation

Frederick

Dwyer

Wang

et al. 2021

J. Phys.: Condens. Matter

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Atomic precision advanced manufacturing (APAM) leverages the highly reactive nature of Si dangling bonds relative to H- or Cl-passivated Si to selectively adsorb precursor molecules into lithographically defined areas with sub-nanometer resolution. Due to the high reactivity of dangling bonds, this process is confined to ultra-high vacuum (UHV) environments, which currently limits its commercialization and broad-based appeal. In this work, we explore the use of halogen adatoms to preserve APAM-derived lithographic patterns outside of UHV to enable facile transfer into real-world commercial processes. Specifically, we examine the stability of H-, Cl-, Br-, and I-passivated Si(100) in inert N2 and ambient environments. Characterization with scanning tunneling microscopy and x-ray photoelectron spectroscopy (XPS) confirmed that each of the fully passivated surfaces were resistant to oxidation in 1 atm of N2 for up to 44 h. Varying levels of surface degradation and contamination were observed upon exposure to the laboratory ambient environment. Characterization by ex situ XPS after ambient exposures ranging from 15 min to 8 h indicated the Br– and I–passivated Si surfaces were highly resistant to degradation, while Cl–passivated Si showed signs of oxidation within minutes of ambient exposure. As a proof-of-principle demonstration of pattern preservation, a H–passivated Si sample patterned and passivated with independent Cl, Br, I, and bare Si regions was shown to maintain its integrity in all but the bare Si region post-exposure to an N2 environment. The successful demonstration of the preservation of APAM patterns outside of UHV environments opens new possibilities for transporting atomically-precise devices outside of UHV for integrating with non-UHV processes, such as other chemistries and commercial semiconductor device processes.

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Section: Co-passivation For Pattern Preservationmentioning

confidence: 70%

“…In conclusion, the capability to form atomically-precise halogen-passivated regions on an otherwise H-passivated sample has been previously limited to UHV [14,41,42]. The results presented here study the stability of these samples in non-UHV environments to extend the use of atomic precision patterning to applications outside of UHV.…”

Section: Discussionmentioning

confidence: 90%

The stability of Cl-, Br-, and I-passivated Si(100)-(2 × 1) in ambient environments for atomically-precise pattern preservation

Frederick

Dwyer

Wang

et al. 2021

J. Phys.: Condens. Matter

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“…By contrast, in the door-opening mechanism, fluctuations happen permanently at all locations, and the statistical model describing the distribution of displacements is different from the vacancy mechanism. The mechanism is also different from other diffusion mechanisms observed on adsorbate-covered solid surfaces. , In the mentioned case of O atoms in a CO matrix on a Ru(0001) surface, the resulting mobility of the O atoms was almost as high as on the bare Ru surface. , …”

Section: Introductionmentioning

confidence: 70%

“…The mechanism is also different from other diffusion mechanisms observed on adsorbate-covered solid surfaces. 17,18 In the mentioned case of O atoms in a CO matrix on a Ru(0001) surface, the resulting mobility of the O atoms was almost as high as on the bare Ru surface. 11,12 The Ru(0001)/O + CO system had been chosen for these investigations because the relatively strongly bound O atoms embedded in the highly mobile layer of CO molecules can model typical situations on catalyst surfaces.…”

Section: ■ Introductionmentioning

confidence: 95%

Diffusion of O Atoms on a CO-Covered Ru(0001) Surface─A Combined High-Speed Scanning Tunneling Microscopy and Density Functional Theory Study at an Enhanced CO Coverage

et al. 2023

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The diffusion of adsorbed O atoms on a CO-covered Ru(0001) surface has recently been explained by a "door-opening" mechanism which is driven by fluctuations in the CO layer. Here, we analyze how this mechanism changes at a higher CO coverage than the 0.33 monolayers applied in the previous study and, therefore, lower concentrations of empty sites. High-speed scanning tunneling microscopy was used to track the O atoms. A statistical model based on nearest-neighbor jumps and uniform hopping probabilities into the six equivalent directions of the Ru(0001) lattice describes the data well. Surprisingly, the hopping rates, which involve site exchanges with CO molecules, are higher than the site exchanges at 0.33 monolayers. Density functional theory calculations were performed to explain these observations. The configurations of the CO molecules around the adsorbed O atoms obtained at the higher CO coverage are disordered. Displacements of CO molecules cost less energy than displacements in the ordered ( 3 3 )R 30 × °structure of the previous study. In addition, the activation energies for the jumps of the O atoms are lowered by enhanced O/CO repulsions. The atomic processes are thus faster at the higher coverage, but the general features of the door-opening mechanism remain valid.

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Reactivity of Silicon Surfaces in the Presence of Adsorbed Hydrogen and Chlorine

Cavallotti¹

2010

Chemical Vapor Deposition

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The desorption of hydrogen and hydrogen chloride from Si surfaces is the rate-determining step of the low temperature CVD of silicon from both hydrogenated and chlorinated precursors. Thus, in order to model the deposition process, the rate of these reactions must be known to a high level of accuracy. In this work, the surface desorption kinetics of H 2 and HCl from the Si(100)2 T 1 surface is investigated by modeling the surface through clusters of various dimensions (up to 60 Si atoms) and determining the reaction energies at the B3LYP, and coupled cluster methodology with inclusion of single, double and a perturbative estimation of triple excitations (CCSD(T)) levels. The investigated mechanisms are the pairwise intradimer and the 4H-2H reaction pathways. The desorption activation energy (57.4 kcal mol À1 ) and adsorption barriers (15.9 kcal mol À1 ) calculated for H 2 for the 4H and 2H pathways are in good agreement with experimental data, confirming that these are the H 2 main desorption and adsorption routes. The reaction mechanism of HCl is different to that of H 2 . The calculations in fact indicate that the less activated desorption pathway (65.0 kcal mol À1) is the intradimer mechanism, followed by the 2H pathway (67.1 kcal mol À1 ), which might thus compete with the intradimer pathway at low surface coverage. The HCl adsorption barrier on Si dimers is small (0.6 À 4.8 kcal mol À1), confirming the high reactivity of HCl with Si surfaces.

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Possibility of direct exchange diffusion of hydrogen on theCl/Si(100)−2×1surface

Cited by 8 publications

References 37 publications

The stability of Cl-, Br-, and I-passivated Si(100)-(2 × 1) in ambient environments for atomically-precise pattern preservation

The stability of Cl-, Br-, and I-passivated Si(100)-(2 × 1) in ambient environments for atomically-precise pattern preservation

Diffusion of O Atoms on a CO-Covered Ru(0001) Surface─A Combined High-Speed Scanning Tunneling Microscopy and Density Functional Theory Study at an Enhanced CO Coverage

Reactivity of Silicon Surfaces in the Presence of Adsorbed Hydrogen and Chlorine

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