Phase transition of the Si(001) surface below 100 K

Kondo, Yasushi; Amakusa, T.; Iwatsuki, Masashi; Tokumoto, Hiroshi

doi:10.1016/s0039-6028(00)00391-5

Cited by 81 publications

(56 citation statements)

References 29 publications

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“…The buckled dimers are observed predominantly at low temperatures ͑110-120 K͒. 5,8 However, recent STM studies reported contradictory results upon further cooling ͑below 65 K͒. Kondo et al predicted that the symmetric dimer is the ground state, 8 whereas others concluded that reappearance of the symmetric dimers at very low temperatures results from a reduced flipping barrier.…”

Section: Introductionmentioning

confidence: 99%

“…5,8 However, recent STM studies reported contradictory results upon further cooling ͑below 65 K͒. Kondo et al predicted that the symmetric dimer is the ground state, 8 whereas others concluded that reappearance of the symmetric dimers at very low temperatures results from a reduced flipping barrier. 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.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

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

View full text Add to dashboard Cite

show abstract

“…The dimer on the Si ͑001͒ surface was thought to have a buckled structure for the last decade, 34 -38 however, recent low temperature scanning tunneling microscopy ͑STM͒ observations suggest symmetric dimers. 39,40 While the DFT calculations [35][36][37][38] predict buckled dimers on the Si ͑001͒ surface, correlated ab initio calculations 41,42 predict symmetric dimers. So, both experiment and theory remain unresolved regarding this issue.…”

Section: Introductionmentioning

confidence: 99%

Multiconfigurational self-consistent field study of the silicon carbide (001) surface

Tamura

Gordon

2003

The Journal of Chemical Physics

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Multiconfigurational self-consistent field calculations have been performed to investigate structural and electronic properties of cubic siliconcarbide (001) (SiC (001)) surfaces. The dimer on silicon-terminated SiC (001) (Si-SiC (001)) is found to be diradical in nature, due to destabilization of the π bond by bending the dimer. Since the SiClattice constant is larger than that of diamond, the >C=C< dimer on the carbonterminated SiC (001) (C-SiC (001)) surface is flatter and its π bond is stronger than those on diamond (001). The bridging dimer on the C-SiC (001) exhibits relatively small multiconfigurational character despite its bent geometry. H2adsorption onto the Si-SiC (001) diradical dimer is more favorable than that onto the partial π bonded Si (001) dimer. As the dimer geometry becomes flatter, the π bond becomes stronger and the H2adsorption on the dimer becomes less favorable. Multiconfigurational self-consistent field calculations have been performed to investigate structural and electronic properties of cubic silicon carbide ͑001͒ ͑SiC ͑001͒͒ surfaces. The dimer on silicon-terminated SiC ͑001͒ ͑Si-SiC ͑001͒͒ is found to be diradical in nature, due to destabilization of the bond by bending the dimer. Since the SiC lattice constant is larger than that of diamond, the ϾCvCϽ dimer on the carbon-terminated SiC ͑001͒ ͑C-SiC ͑001͒͒ surface is flatter and its bond is stronger than those on diamond ͑001͒. The bridging dimer on the C-SiC ͑001͒ exhibits relatively small multiconfigurational character despite its bent geometry. H 2 adsorption onto the Si-SiC ͑001͒ diradical dimer is more favorable than that onto the partial bonded Si ͑001͒ dimer. As the dimer geometry becomes flatter, the bond becomes stronger and the H 2 adsorption on the dimer becomes less favorable.

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“…With the rapid development of low-temperature UHV-STM, various structures, such as static (2×1) [36], dynamic (2×1) [37,38], p(2×2) [39], and c(4×2), have been proposed as the ground state of the Si(001) surface [40]. Here, the static (2×1) structure is composed of symmetric dimers.…”

Section: Stm Phase Manipulation By Carrier Injectionmentioning

confidence: 99%

Active nanocharacterization of nanofunctional materials by scanning tunneling microscopy

Fujita

Sagisaka

2008

Science and Technology of Advanced Materials

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Recent developments in the application of scanning tunneling microscopy (STM) to nanofabrication and nanocharacterization are reviewed. The main focus of this paper is to outline techniques for depositing and manipulating nanometer-scale structures using STM tips. Firstly, the transfer of STM tip material through the application of voltage pulses is introduced. The highly reproducible fabrication of metallic silver nanodots and nanowires is discussed. The mechanism is thought to be spontaneous point-contact formation caused by field-enhanced diffusion to the apex of the tip. Transfer through the application of z-direction pulses is also introduced. Sub-nanometer displacement pulses along the z-direction form point contacts that can be used for reproducible nanodot deposition. Next, the discovery of the STM structural manipulation of surface phases is discussed. It has been demonstrated that superstructures on Si(001) surfaces can be reverse-manipulated by controlling the injected carriers. Finally, the fabrication of an atomic-scale one-dimensional quantum confinement system by single-atom deposition using a controlled point contact is presented. Because of its combined nanofabrication and nanocharacterization capabilities, STM is a powerful tool for exploring the nanotechnology and nanoscience fields.

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Phase transition of the Si(001) surface below 100 K

Cited by 81 publications

References 29 publications

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

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

Multiconfigurational self-consistent field study of the silicon carbide (001) surface

Active nanocharacterization of nanofunctional materials by scanning tunneling microscopy

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