Atomically Resolved Local Variation of the Barrier Height of the Flip-Flop Motion of Single Buckled Dimers of Si(100)

Hata, Kenji; Sainoo, Yasuyuki; Shigekawa, Hidemi

doi:10.1103/physrevlett.86.3084

Cited by 89 publications

(73 citation statements)

References 14 publications

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“…They demonstrated that the tunneling current recorded above one of the atoms of a dimer of the Ge(001) surface exhibited telegraph like noise. A few years later similar experiments were reported for Si(001) by Hata et al [14], Yoshida et al [15], and Pennec et al [16]. The latter measurements demonstrated that the flip-flop motion of the dimers can be interpreted in terms of a so-called phason.…”

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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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“…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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Dynamics and Energetics of Ge(001) Dimers

2006

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“…9 This low temperature phase transition ͑around 40 K͒ was also observed by several other groups using STM, synchrotron-radiation photoelectron spectroscopy, and low-energy electron diffraction ͑LEED͒. [10][11][12] However, these later experiments disagree with the stable symmetric dimer inferred at 0 K by Kondo et al Instead, they suggest an asymmetric p(2ϫ1) phase, a p(2ϫ2) phase, or a disordered p(2ϫ1) phase due to the dynamic flip-flop motion of the buckled dimers at low ͑Ͻ40 K͒ temperatures.…”

Section: Introductionmentioning

confidence: 65%

“…In experiments, there have been numerous indications from spectroscopy, 6 diffraction, 7 and scanning tunneling microscopy ͑STM͒, [1][2][3]5,[9][10][11][12] that the dimers are intrinsically buckled above 100 K. The dominant appearance of the symmetric dimers in STM images at room temperature was ascribed to the dynamic flipping motion of the buckled dimers. The buckled dimers are observed predominantly at low temperatures ͑110-120 K͒.…”

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confidence: 99%

Are both symmetric and buckled dimers on Si(100) minima? Density functional and multireference perturbation theory calculations

Jung

Shao

Gordon

et al. 2003

The Journal of Chemical Physics

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We report a spin-unrestricted density functional theory(DFT) solution at the symmetric dimer structure for cluster models of Si(100). With this solution, it is shown that the symmetric structure is a minimum on the DFTpotential energy surface, although higher in energy than the buckled structure. In restricted DFT calculations the symmetric structure is a saddle point connecting the two buckled minima. To further assess the effects of electron correlation on the relative energies of symmetric versus buckled dimers on Si(100), multireference second order perturbation theory (MRMP2) calculations are performed on these DFT optimized minima. The symmetric structure is predicted to be lower in energy than the buckled structure via MRMP2, while the reverse order is found by DFT. The implications for recent experimental interpretations are discussed. KeywordsDensity functional theory, Perturbation theory, Electron correlation calculations, Potential energy surfaces Disciplines Chemistry CommentsThe following article appeared in Journal of Chemical Physics 119 (2003) We report a spin-unrestricted density functional theory ͑DFT͒ solution at the symmetric dimer structure for cluster models of Si͑100͒. With this solution, it is shown that the symmetric structure is a minimum on the DFT potential energy surface, although higher in energy than the buckled structure. In restricted DFT calculations the symmetric structure is a saddle point connecting the two buckled minima. To further assess the effects of electron correlation on the relative energies of symmetric versus buckled dimers on Si͑100͒, multireference second order perturbation theory ͑MRMP2͒ calculations are performed on these DFT optimized minima. The symmetric structure is predicted to be lower in energy than the buckled structure via MRMP2, while the reverse order is found by DFT. The implications for recent experimental interpretations are discussed.

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“…Around 2000, I was conducting research on atomic structure analysis of semiconductor surfaces using the scanning tunneling microscope at Tsukuba University, and I went to the American Vacuum Society (the largest and most authoritative society in the field of surface science) to give a lecture presentation of my greatest finding during the preceding few years (this was later published in Physical Review Letter). [8] In a lecture hall having seating capacity of 300 that was normally filled with several hundred people, there were only ten people. Most of them were Japanese.…”

Section: Research Policy That Set the Direction And My Thoughtsmentioning

confidence: 99%

A super-growth method for single-walled carbon nanotube synthesis

Hata¹

2016

Synthesiology English edition

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Atomically Resolved Local Variation of the Barrier Height of the Flip-Flop Motion of Single Buckled Dimers of Si(100)

Cited by 89 publications

References 14 publications

Dynamics and Energetics of Ge(001) Dimers

Dynamics and Energetics of Ge(001) Dimers

Are both symmetric and buckled dimers on Si(100) minima? Density functional and multireference perturbation theory calculations

A super-growth method for single-walled carbon nanotube synthesis

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