Identification of Tetramers in Silver Films Grown on the Si(001) Surface at Room Temperature

Huang, Kai; Huxter, William S.; Singh, Chandra Veer; Nogami, J.

doi:10.1021/acs.jpclett.8b02746

Cited by 5 publications

(14 citation statements)

References 46 publications

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“…DFT relaxation performed on previously proposed atomic structure models , fail to match experimental observations. The more recent model, which features a Ag square tetramer placed in between four Si dimers, produced a structure that remains topographically consistent with experimental data. This work provides a comprehensive view of the agreement between the DFT calculations based on the new model and all aspects of the experimental STM data, including the configuration of domain boundaries in the (2 × 2)-Ag phase and a bias dependent Ag film contrast reversal.…”

Section: Introductionsupporting

confidence: 71%

“…The model proposed by Park et al (Figure b), referred to as the inequivalent dimer (ID) model (two inequivalent Ag dimer sites), is similar to the double layer model used to describe alkali-metal structures on Si(001), placing Ag dimers perpendicular to the Si dimer bonds in the hollow and pedestal sites. The third model, referred to as the square tetramer (ST) model, places four Ag atoms in a square over the hollow site with each Ag atom close to a Si dimer atom (Figure c). Table lists adsorption energies, bond lengths, and relevant angles taken with respect to the surface plane.…”

Section: Results and Discussionmentioning

confidence: 99%

“…Green lines are placed over the Si dimer bond along the direction of the dimer row, and blue lines are placed along Si dimer bond. The 2D mesh was reproduced similar to ref .…”

Section: Results and Discussionmentioning

confidence: 99%

“…The first atomic layer of Ag typically grows as 2D patches with 1 monolayer (ML) of Ag atom density, i.e., one silver atom per underlying Si substrate atom (1 ML = 6.78 × 10 14 atoms/cm 2 ). Experimental data shows that the 1 ML Ag film forms an ordered (2 × 2)-Ag phase. ,,, Two different experimentally derived models have been proposed claiming that the (2 × 2)-Ag phase is based on Ag dimers. , However, a recent low-temperature (LT)-STM study provided evidence that Ag tetramers are the fundamental unit of the (2 × 2)-Ag phase . As the Ag coverage surpasses 1 ML, an unwetting phenomenon occurs. , Ag from the 2D layer unwets from the Si(001) surface and nucleates into three-dimensional (3D) islands.…”

Section: Introductionmentioning

confidence: 99%

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How Silver Grows on the Silicon (001) Surface: A Theoretical and Experimental Investigation

Huxter

Huang

Nogami

et al. 2018

ACS Appl. Electron. Mater.

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When a silver film is grown on the Si(001) surface at room temperature, it forms a monolayer density film with a (2 × 2) periodicity. Previous models of this (2 × 2) surface, simulated by density functional theory (DFT), are found to be inconsistent with experimental observations. The DFT simulations provide evidence that a new model, the square tetramer model, describes the structure of the observed (2 × 2)-Ag phase and is fully consistent with scanning tunneling microscopy data. Theoretical evidence of a covalent bond shared between the Ag and Si is found that matches previous experiments. Interestingly, the simulations also show that the stoichiometry between Si and Ag changes with metal coverage as adsorbate−adsorbate and adsorbate−substrate interactions balance out. At low coverages, when individual Ag adatoms interact solely with Si, a two-to-one Si−Ag−Si interaction scheme is energetically preferred. At 1 monolayer, when Ag−Ag interactions must be considered, a one-to-one Si− Ag interaction scheme is preferred, as it maximizes Ag−Ag interactions.

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Section: Introductionsupporting

confidence: 71%

Section: Results and Discussionmentioning

confidence: 99%

“…Green lines are placed over the Si dimer bond along the direction of the dimer row, and blue lines are placed along Si dimer bond. The 2D mesh was reproduced similar to ref .…”

Section: Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

How Silver Grows on the Silicon (001) Surface: A Theoretical and Experimental Investigation

Huxter

Huang

Nogami

et al. 2018

ACS Appl. Electron. Mater.

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“…The Ag/Si(100) system can serve as an example. Though onset of the extensive study of the system dates back to the mid-1990s, − atomic arrangement of its surface reconstructions still remains unknown with the only fresh exception; namely, the atomic structure of the Si(100)2×2-Ag reconstruction forming at room temperature (RT) has very recently been determined. , The advanced key idea that has allowed the authors to get a success was to adopt an Ag tetramer as a reconstruction building block instead of a more habitual Ag dimer.…”

mentioning

confidence: 99%

Solving a Long-Standing Problem Regarding Atomic Structure of Si(100)2×3-Ag

Mihalyuk

Kotlyar

Utas

et al. 2021

J. Phys. Chem. Lett.

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The atomic structure of the Si(100)2×3-Ag reconstruction has remained unknown for more than 25 years since its first observation with scanning tunneling microscopy, despite a relatively small unit cell and seeming abundance of the available experimental data. We propose a structural model of the Si(100)3×2-Ag reconstruction which comfortably fits all the principal experimental findings, including our own and those reported in the literature. The model incorporates 3 Si atoms and 4 Ag atoms per the 2 × 3 unit cell forming linear atomic chains along the 3a Si -periodic direction. A peculiar feature of the Si(100)2×3-Ag structure is the occurrence of the inner Si dimers in the second atomic layer from the top of the Si(100) substrate. The reconstruction is proved to possess semiconducting properties.

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Adsorption and Migration of Silver on Group IV Semiconductor (001) Surfaces by Density Functional Theory

2022

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We examined the adsorption and subsequent migration of a silver monomer (Ag 1 ), a dimer (Ag 2 ), and a tetramer (Ag 4 ) on the group IV(001) (IV = C, Si, and Ge) semiconductor surfaces, using density functional theory. For Ag 1 on IV(001), the adsorption is favored to be covalently attached at the trench between the substrate rows, yielding the heats of adsorption of 1.91, 2.53, and 2.07 eV on C(001), Si(001), and Ge(001), respectively. The migration of Ag 1 is, however, by way of the substrate rows regardless of the migration direction, giving isotropic barriers of 0.08, 0.51, and 0.38 eV on C(001), Si(001), and Ge(001), respectively. As the size of silver species increases, there emerge quasi-covalent adsorbate−adsorbate (Ag−Ag) interactions, in addition to the covalent adsorbate−substrate interactions, as showcased by the adsorption of Ag 2 and Ag 4 on Si(001). The heats of adsorption are 2.16 eV for Ag 2 and 2.53 eV for Ag 4 . Consequently, the migration of Ag 2 and Ag 4 is enabled inside the trench between Si rows, leading to anisotropic barriers; that is, Ag 2 favors migrating across (0.26 eV in the barrier) over along (0.63 eV in the barrier) Si rows, whereas Ag 4 favors migrating along (0.24 eV in the barrier) over across (0.68 eV in the barrier) Si rows.

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Identification of Tetramers in Silver Films Grown on the Si(001) Surface at Room Temperature

Cited by 5 publications

References 46 publications

How Silver Grows on the Silicon (001) Surface: A Theoretical and Experimental Investigation

How Silver Grows on the Silicon (001) Surface: A Theoretical and Experimental Investigation

Solving a Long-Standing Problem Regarding Atomic Structure of Si(100)2×3-Ag

Adsorption and Migration of Silver on Group IV Semiconductor (001) Surfaces by Density Functional Theory

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