Herringbone and triangular patterns of dislocations in Ag, Au, and AgAu alloy films on Ru(0001)

Ling, Wai Li; Hamilton, J. C.; Thürmer, Konrad; Thayer, Gayle Echo; Figuera, Juan de la; Hwang, R. Q.; Carter, C. Barry; Bartelt, N. C.; McCarty, K. F.

doi:10.1016/j.susc.2006.01.055

Cited by 59 publications

(62 citation statements)

References 58 publications

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“…2(c) which shows triangular-looplike distortions of the regular herringbone reconstruction even after only one MoS 2 growth cycle. These perturbations are similar to previously reported STM data of Au thin films grown on Ru(0001) which suggest that such triangular-like structures are amenable to relieving strain in stacked hexagonal layers 41 . The STM images also reveal the presence of distinct line defects, as shown in Fig.…”

Section: Resultssupporting

confidence: 90%

Synthesis of Epitaxial Single-Layer MoS₂ on Au(111)

et al. 2015

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We present a method for synthesizing large area epitaxial single-layer MoS2 on the Au(111) surface in ultrahigh vacuum. Using scanning tunneling microscopy and low energy electron diffraction, the evolution of the growth is followed from nanoscale single-layer MoS2 islands to a continuous MoS2 layer. An exceptionally good control over the MoS2 coverage is maintained using an approach based on cycles of Mo evaporation and sulfurization to first nucleate the MoS2 nano-islands and then gradually increase their size. During this growth process the native herringbone reconstruction of Au (111) is lifted as shown by low energy electron diffraction measurements. Within these MoS2 islands, we identify domains rotated by 60• that lead to atomically sharp line defects at domain boundaries. As the MoS2 coverage approaches the limit of a complete single-layer, the formation of bilayer MoS2 islands is initiated. Angle-resolved photoemission spectroscopy measurements of both single and bilayer MoS2 samples show a dramatic change in their band structure around the center of the Brillouin zone. Brief exposure to air after removing the MoS2 layer from vacuum is not found to affect its quality.

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Section: Resultssupporting

confidence: 90%

Synthesis of Epitaxial Single-Layer MoS₂ on Au(111)

et al. 2015

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“…This significantly revises the structure models previously reported for this system. 4,18,19 Experiments were carried out in three ultrahigh vacuum multichamber systems (p total = 3 × 10 −11 − 1 × 10 −10 mbar), all equipped with standard surface preparation tools and scanning tunneling microscopy (STM). The first is used for high-resolution measurements with a low-temperature STM operated at 77 K, the second combines an RT micro-STM with low-energy ion scattering (LEIS) using 1 keV He + ions, and the third combines an RT-STM with x-ray photoelectron diffraction (XPD).…”

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confidence: 99%

Interface-confined mixing and buried partial dislocations for Ag bilayer on Pt(111)

et al. 2012

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The trigonal strain-relief pattern formed by an Ag bilayer on Pt(111) is a prominent example for dislocation networks and their use as nanotemplates. However, its atomic structure has not been solved. Combining scanning tunneling microscopy, low-energy ion scattering, and x-ray photoelectron diffraction, we demonstrate that, unexpectedly, about 22% of the atoms exchange across the Ag/Pt interface, and that the partial dislocations defining the trigonal network are buried in the Pt interface layer. We present an embedded-atom-method simulation identifying the lowest energy structure compatible with all experimental findings. Strain-relief patterns formed by heteroepitaxial films act as templates for the self-assembly of highly ordered nanostructure superlattices. 1 The first system where the growth kinetics has been studied is a superlattice of Ag islands grown on a trigonal network (TN) formed by two monolayers (ML) of Ag/Pt(111). 2,3 The system has been modeled by assuming a network of surface Shockley partial dislocations 4 acting as repulsive line defects and thus confining the deposited Ag adatoms into the (25 × 25) unit cells. 2,3 However, the topmost Ag layer of the TN has recently been shown to be nearly perfectly hexagonal; hence there are no partial dislocations at the surface. 5,6 Nevertheless, the TN exhibits remarkable template functions. Well-ordered sputter holes 5 and adsorbed organic molecules, 6-8 as well as strong spatial variations of the local work function 9 have been reported. A fundamental understanding of any template function evidently requires knowledge of its atomic structure. 10 Despite considerable efforts, a realistic atomistic model has not yet been developed for the 2 ML Ag/Pt(111) TN.Silver on Pt(111) is a system with a particularly rich surface phase diagram. Submonolayers deposited at room temperature (RT) are pseudomorphic for islands smaller than 20 nm, whereas larger islands form surface partial dislocations. 11,12 Counterintuitively, the dislocations disappear at a full monolayer (defined as one Ag atom per Pt substrate atom), where the stress resulting from the misfit is largest. This has been related to the chemical adatom potential and to the presence of an adatom gas. 11 Further growth at RT leads to a striped phase (SP) 4,13 with pairs of partial dislocations. Upon annealing to 800 K the SP transforms into the stable TN structure. 4 Deposition of Ag submonolayers at higher temperature, or their annealing at T > 620 K, leads to a real mixture formed by monolayer Ag clusters embedded into the uppermost atomic substrate layer for a coverage < 0.5 ML and the reverse for 0.5 ML < < 1.0 ML. 14 This mixing has been confirmed by CO titration 15 and He-atom scattering 16 and is confined to the uppermost layer; hence, the name "surface alloy". 17 For 1.0 ML, especially for = 2 ML, Ag and Pt were believed to be phase separated up to the Ag desorption temperature.In this paper we report the surprising observation that the system mixes again for 2 ML Ag in the TN structure. This mi...

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“…The STM results show that well-ordered islands are formed upon periodic dislocation network [3][4][5]. The dislocation network gives rise to periodic strain on the film surface.…”

Section: Introductionmentioning

confidence: 95%

“…At heterointerfaces, periodic dislocation network could appear due to the lattice misfit [2][3][4][5]. The STM results show that well-ordered islands are formed upon periodic dislocation network [3][4][5].…”

Section: Introductionmentioning

confidence: 97%