Streak patterns in low-energy electron diffraction on Si(001)

Kubota, M.; Murata, Yoshitada

doi:10.1103/physrevb.49.4810

Cited by 79 publications

(28 citation statements)

References 18 publications

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“…1͑b͒ by noting that they fade out very slowly with temperature. It has not been possible to reproduce the streaks using Monte Carlo calculations 11 and it is believed 12 that a strong short range order along the dimer rows, induced by the anisotropic displacement of secondlayer atoms, is responsible for the streaks appearing in LEED. Our results suggest that there may be a correlation between the streaks and the surface state that appears 3 eV below E F around J 2 Ј.…”

Section: Resultsmentioning

confidence: 99%

Origin of a surface state above the Fermi level on Ge(001) and Si(001) studied by temperature-dependent ARPES and LEED

et al. 2008

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Origin of a surface state above the Fermi level on Ge(001) and Si(001) studied by temperature-dependent ARPES and LEED, 2008, Physical Review B. Condensed Matter and Materials Physics, (77) Variable temperature photoemission studies in the literature have revealed the presence of a surface state above the Fermi level on clean Ge͑001͒. We present photoemission and low energy electron diffraction results from Ge͑001͒ obtained between 185 and 760 K. Our measurements show a peak above the Fermi level with a maximum intensity at a sample temperature of around 625 K. At higher temperatures, we observe a gradual decrease in the intensity. Angle resolved spectra show that the surface state has a k ʈ dependence and is therefore not attributed to defects. Very similar results were obtained on both an intrinsic ͑30 ⍀ cm͒ and a 10 m ⍀ cm n-type sample. The overall appearance of the spectral feature is found to be quite insensitive to sample preparation. Low energy electron diffraction investigations show how the sharp c͑4 ϫ 2͒ pattern becomes streaky and finally turns into a 2 ϫ 1 pattern. The onset of the structure above the Fermi level takes place just before all c͑4 ϫ 2͒ streaks have disappeared which corresponds to a temperature of around 470 K. On Si͑001͒, we also observe photoemission intensity above the Fermi level. It is weaker than on Ge͑001͒ and appears at higher temperature. We find that the emission above the Fermi level can be explained by thermal occupation of the * band derived from a 2 ϫ 1 ordering of asymmetric dimers on the surface.

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Section: Resultsmentioning

confidence: 99%

Origin of a surface state above the Fermi level on Ge(001) and Si(001) studied by temperature-dependent ARPES and LEED

et al. 2008

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“…The order-disorder transition is almost complete near T ഠ 200 K [22], which explains why Ds ss ͑T͒ reaches a minimum (maximum surface scattering). To illustrate this point we also show the intensity of the (3͞2, 3͞4) spot in LEED as a function of T͞T c as reported in Ref.…”

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confidence: 75%

“…To illustrate this point we also show the intensity of the (3͞2, 3͞4) spot in LEED as a function of T͞T c as reported in Ref. [22], which reflects the order parameter of the c͑4 3 2͒ reconstruction. Figure 4 strongly suggests a link between surface-state conductance and structural (dis)order on the surface.…”

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confidence: 99%

Surface Conductance near the Order-Disorder Phase Transition on Si(100)

Yoo

Weitering

2001

Phys. Rev. Lett.

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The surface conductance of the Si͑100͒-͑2 3 1͒ surface was measured as a function of temperature on a fully depleted Si͑100͒͞SiO 2 ͞Si substrate. The surface-state conductance is surprisingly large and reveals a clear signature of the c͑4 3 2͒ ! 2 3 1 order-disorder phase transition of buckled Si dimers on Si(100). Surface scattering increases with decreasing c͑4 3 2͒ order on the surface.

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“…While the correspondence of the actual atomic structure to the two-dimensional Ising model is not so straightforward as for the transition between c(4×2) and (2×1) on Si(001) [100][101][102], it is possible to map the (2 √ 2×2 √ 2)R45 • −(2×2) transition onto the Ising model as shown in Fig. 17.…”

Section: Critical Behavior Of the Latticementioning

confidence: 99%

Surface Peierls transition on Cu(001) covered with heavier p-block metals

Aruga

2006

Surface Science Reports

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The Cu(001) surface covered with submonolayer coverages of In and Sn undergoes phase transitions at around 350-400 K. The transition is associated with the surface electronic structure change between low-temperature gapped and high-temperature ungapped ones. The energy gap positions in the k space coincide with the surface Brillouine zone boundaries of the low-temperature phases. These observations imply that the phase transitions are classified into the Peierls-type charge density wave (CDW) phase transition. The CDW ground states are characterized by large overall CDW gaps and long CDW correlation lengths. Structural studies show that the transitions are associated with order-disorder processes. This suggests that these are in strong-coupling regime. However, the associated gapped-ungapped change suggests that the electronic terms play significant role, in contradiction with the strong-coupling scenario. Based on the results of recent works on precise temperature dependence of the CDW gap and critical X-ray scattering, the origin of this dual nature and the detailed mechanism of the phase transition is discussed. It is suggested that the electronic entropy of the CDW ground state is not governed by the overall energy gap but by the gap between the upper band minimum and the Fermi level of the whole system. The dual nature of the surface Peierls transition on Cu(001) originates, on one hand, from the existence at metal surfaces of the two characteristic energy gaps: the overall gap, which determines the CDW stabilization energy, and the upper gap, which governs the electronic entropy. On the other hand, the CDW correlation length is suggested to play another significant role in determining the nature of the Peierls transition. The classification of the Peierls transisions according to the CDW correlation length and the gap size is discussed. It is suggested that the surface Peierls transition on metal-covered Cu(001) covered with heavier p-block metallic elements are qualitatively different from both the weak-coupling CDW transition, with long CDW correlation length and small gaps, and the strong-coupling CDW transitions, with short correlation lengths and large gaps, and should be classified into the third class, which is characterized by long coherence and strong coupling.

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Streak patterns in low-energy electron diffraction on Si(001)

Cited by 79 publications

References 18 publications

Origin of a surface state above the Fermi level on Ge(001) and Si(001) studied by temperature-dependent ARPES and LEED

Origin of a surface state above the Fermi level on Ge(001) and Si(001) studied by temperature-dependent ARPES and LEED

Surface Conductance near the Order-Disorder Phase Transition on Si(100)

Surface Peierls transition on Cu(001) covered with heavier p-block metals

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