Detection of the flip-flop motion of buckled dimers on a Ge(001) surface by STM

Sato, Tomoshige; Iwatsuki, Masashi; Tochihara, Hiroshi

doi:10.1093/oxfordjournals.jmicro.a023644

Cited by 49 publications

(33 citation statements)

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“…In case of the pinned-buckled dimers of the c4 2 domain, the D up bonds are relatively more populated with respect to the D down bonds. In the case of the symmetric-appearing dimers in the 2 1 domains, the D down and D up bonds are almost equally populated-in a time averaged manner-due to the high frequency of the flip-flopping of the dimers between two buckled states [10,17]. Consequently, a band that would form due to D up bonds can be expected to appear sharper in c4 2 domains, while the same band in 2 1 would look more smeared or attached to a nearby, high-intensity, state as a shoulder.…”

Section: Fig 2 (A)mentioning

confidence: 99%

“…In their initiating work, Kevan and Stoffel [1] suggested that this metallicity may be due to the 2 1 domains. In these domains, the dimers are flip-flopping above a critical temperature and passing through a symmetric state during their switching between two buckled states [10,11]. Showing that the state does not exist at low temperatures -when all the dimers are frozen in a buckled state -Kevan and Stoffel [1] have associated this metallic state to symmetric dimers.…”

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confidence: 99%

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Electronic Properties of(2×1)andc(4×2)Domains on Ge(001) Studied by Scanning Tunneling

2004

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The surface electronic structure of Ge(001) was studied by scanning tunneling spectroscopy. The measured surface densities of states unequivocally reveal the presence of a metallic state on the 2 1 domains, which is absent on the c4 2 domains. This metallic state, so far observed only in integral measurements, is attributed to the flip-flopping dimers that constitute the 2 1 domains. Our data also reveal a set of previously unresolved surface states, in perfect agreement with published theoretical predictions.

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Section: Fig 2 (A)mentioning

confidence: 99%

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confidence: 99%

Electronic Properties of(2×1)andc(4×2)Domains on Ge(001) Studied by Scanning Tunneling

2004

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“…At room temperature, the dimers are flip-flopping between two buckled states. 24 A Pt adsorption to the D site releases a considerable amount of energy (up to 6.5 eV). We speculate that the released energy may cause a chain reaction that may lead to the breaking of many surface Ge bonds, destabilizing the Pt atom and eliminating the chance of existence of this configuration.…”

Section: Discussionmentioning

confidence: 99%

Initial stages ofPtgrowth onGe(001)studied by scanning tunneling microscopy and density functional theory

et al. 2004

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We have studied the initial stages of submonolayer Pt growth on the Ge͑001͒. We have observed several stable and meta-stable adsorption configurations of Pt atoms at various temperatures. Calculations indicate relatively high binding energies of Pt atoms onto the Ge lattice, at different adsorption sites. Our results show that through-the-substrate bonding (concerted bonding) of two Pt atoms is more favored on Ge͑001͒ surface then a direct Pt-Pt bond. Both our experiments and calculations indicate the breaking of Ge-Ge bonds on the surface in the vicinity of Pt adsorbates. We have also observed the spontaneous generation of 2 + 1 dimer vacancy defects at room temperature that cause the ejection of Ge atoms onto the surface. Finally we have studied the diffusion of Pt atoms into the bulk as a result of annealing and found out that they get trapped at subsurface sites.

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“…The observed symmetric dimers are actually flip flopping rapidly between the two possible buckled configurations [13][14][15][16]. The first direct evidence for this flip-flop motion was provided by Sato, Iwatsuki, and Tochihara [13]. They demonstrated that the tunneling current recorded above one of the atoms of a dimer of the Ge(001) surface exhibited telegraph like noise.…”

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confidence: 93%

“…However, it has been well established since than that the lowest energy configuration is a buckled dimer [11,12]. The observed symmetric dimers are actually flip flopping rapidly between the two possible buckled configurations [13][14][15][16]. The first direct evidence for this flip-flop motion was provided by Sato, Iwatsuki, and Tochihara [13].…”

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confidence: 96%

Dynamics and Energetics of Ge(001) Dimers

2006

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The dynamic behavior of surface dimers on Ge(001) has been studied by positioning the tip of a scanning tunneling microscope over single flip-flopping dimers and measuring the tunneling current as a function of time. We observe that not just symmetric, but also asymmetric appearing dimers exhibit flipflop motion. The dynamics of flip-flopping dimers can be used to sensitively gauge the local potential landscape of the surface. Through a spatial and time-resolved measurement of the flip-flop frequency of the dimers, local strain fields near surface defects can be accurately probed. The silicon and germanium semiconductor group IV (001) surfaces are among the most frequently studied surfaces in literature [1][2][3]. Because of its obvious technological importance to the semiconductor industry, the majority of studies have, however, been devoted to the Si(001) surface rather than the closely related Ge(001) surface. Both (001) surfaces are examples of a system that exhibits both a strong short-range interaction and a weak longrange interaction. The short-range interaction leads to dimerization, i.e., a pairing of nearest-neighbor surface atoms to form a (2 1) reconstruction [4]. The weaker long-range interaction results in various higher-order surface reconstructions, such as p 2 2 and c 4 2 . In several other aspects the Ge(001) surface [2] also turns out to be very similar to the Si(001) surface [3]. The properties and possible applications resulting from the dimerized termination of both surfaces has been the topic of many recent papers, investigating, e.g., the formation of heteroepitaxial nanostructures, the chemical reactivity of the bare (001) surfaces and the application of both surfaces in high-efficiency solar cells [5][6][7][8].

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Detection of the flip-flop motion of buckled dimers on a Ge(001) surface by STM

Cited by 49 publications

References 0 publications

Electronic Properties of(2×1)andc(4×2)Domains on Ge(001) Studied by Scanning Tunneling

Electronic Properties of(2×1)andc(4×2)Domains on Ge(001) Studied by Scanning Tunneling

Initial stages ofPtgrowth onGe(001)studied by scanning tunneling microscopy and density functional theory

Dynamics and Energetics of Ge(001) Dimers

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