Temperature-Dependent Surface States and Transitions of Si(111)-7×7

Demuth, J. E.; Persson, B. N. J.; Schell-Sorokin, A. J.

doi:10.1103/physrevlett.51.2214

Cited by 155 publications

(67 citation statements)

References 19 publications

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“…6 Among the various reconstructions of the Si͑111͒-surface the ͑7 ϫ 7͒ one is not only by far the oldest example but also the best investigated one. [7][8][9][10][11][12][13] ͑For further, in particular older references, see Ref. 9͒ Nevertheless there exists up to now no clear-cut picture as to the detailed reasons which causes its metallicity.…”

Section: Introductionmentioning

confidence: 99%

“…A very narrow ͑local-ized͒ half-filled state at E F ͑width 1 -2 meV͒ was found in the center of a gap in between bands formed by more delocalized electrons. 7,8 Such a density of states distribution is very much reminiscent to the one appearing in single band Hubbard-models if a suitable ratio of onsite Coulomb interaction to the hopping matrix elements ͑bandwidth͒ is chosen. ͑See, e.g., Fig.…”

Section: Introductionmentioning

confidence: 99%

“…Whereas high magnetic fields suppress considerably diffusive contributions to the T 1 -times, low temperatures proved to enhance spectroscopic details in the past. 7,9,27 Additionally the statistical errors are reduced considerably. Moreover the surface preparation and handling has improved substantially ͑for details, see Sec.…”

Section: Introductionmentioning

confidence: 99%

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MetallicSi(111)−(7×7)-reconstruction: A surface close to a Mott-Hubbard metal-insulator transition

et al. 2005

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Li adsorption at extremely low coverages ͑10 −3 ML and below͒ on the metallic Si͑111͒-͑7 ϫ 7͒ surface has been studied by ␤-NMR experiments ͑measurement of T 1 -times͒. Instead of increasing linearly with the sample temperature, as expected for a metallic system, the relaxation rate ␣ =1/T 1 is almost constant in between 50 K and 300 K sample temperature and rises considerably above. Comparison with T 1 -times around 900 K ͑ob-served with 6 Li-NMR͒ excludes adsorbate diffusion as the cause of the relaxation rate. Thus the almost temperature independent relaxation rate below 300 K points to an extremely localized and thus narrow band ͑width about 10 meV͒ which pins the Fermi energy. It is responsible for the metallicity of the ͑7 ϫ 7͒-reconstruction. Because of the steeply rising relaxation rate beyond 300 K this narrow band is located energetically within a gap ͑approximately 100-500 meV wide͒ in between a lower filled and an upper empty ͑Hubbard͒ band. Due to its extremely narrow width it can hardly be detected in photo electron experiments. In dynamical mean field theories based on Hubbard Hamiltonians this kind of density of states is typical for correlated electron systems close to a Mott-Hubbard metal-insulator transition.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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MetallicSi(111)−(7×7)-reconstruction: A surface close to a Mott-Hubbard metal-insulator transition

et al. 2005

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“…Earlier SPV measurements were mostly synchrotron based due to the needed brightness of the source [6][7][8][9][10], but combined with Xray microfocusing and fast accumulation tools, the new generation commercial XP spectrometers can also provide critical information about such materials and devices [11,12]. In a recent publication we reported on capturing of the transient surface photovoltage in n-and p-GaN by XPS where new information about the mechanism of the transients formed by illumination with a ∼50 mW violet (405 nm) laser was brought out and discussed [13].…”

Section: Introductionmentioning

confidence: 99%

XPS for probing the dynamics of surface voltage and photovoltage in GaN

Sezen¹,

Özbay²,

Süzer³

2014

Applied Surface Science

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a b s t r a c tWe describe application of two different data gathering techniques of XPS for probing the dynamics of surface voltage and surface photovoltage (SPV) developed in microseconds to seconds time-domain, in addition to the conventional steady-state measurements. For the longer (seconds to milliseconds) regime, capturing the data in the snapshot fashion is used, but for the faster one (down to microseconds), square wave (SQW) electrical pulses at different frequencies are utilized to induce and probe the dynamics of various processes causing the surface voltage, including the SPV, via the changes in the peak positions. The frequency range covers anywhere from 10 −3 to 10 5 Hz for probing changes due to charging (slow), dipolar (intermediate), and electronic (fast) processes associated with the external stresses imposed. We demonstrate its power by application to n-and p-GaN, and discuss the chemical/physical information derived thereof. In addition, the method allows us to decompose and identify the peaks with respect to their charging nature for a composite sample containing both n-and p-GaN moieties.

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“…XPS-based SPV measurements of semiconducting materials date back three decades using both synchrotron and laboratory-based equipment. [3][4][5][6] However, except for Si ͑Refs. 7 and 8͒ and GaAs, 9,10 no transient SPV measurements using XPS have been reported to date.…”

mentioning

confidence: 99%

Transient surface photovoltage in n- and p-GaN as probed by x-ray photoelectron spectroscopy

Sezen¹,

Özbay²,

Aktaş³

et al. 2011

Applied Physics Letters

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Transient surface photovoltage (SPV) of n and p-GaN was measured using x-ray photoelectron spectroscopy (XPS) with a time resolution of 0.1 s. The measured SPV transients for both n- and p-GaN are 0.1 s, and for the n-GaN they are not affected by flood-gun electrons. However, for the p-GaN, the transient character of the SPV is dramatically changed in the presence of flood-gun electrons. The combination of time-resolved XPS, flood gun, and laser illumination give us a new way to study the surface electronic structure and other surface properties of semiconducting materials in a chemically specific fashion. © 2011 American Institute of Physics

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Temperature-Dependent Surface States and Transitions of Si(111)-7×7

Cited by 155 publications

References 19 publications

MetallicSi(111)−(7×7)-reconstruction: A surface close to a Mott-Hubbard metal-insulator transition

MetallicSi(111)−(7×7)-reconstruction: A surface close to a Mott-Hubbard metal-insulator transition

XPS for probing the dynamics of surface voltage and photovoltage in GaN

Transient surface photovoltage in n- and p-GaN as probed by x-ray photoelectron spectroscopy

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