Surface core-level shifts on clean Si(001) and Ge(001) studied with photoelectron spectroscopy and density functional theory calculations

Eriksson, Peter; Uhrberg, R. I. G.

doi:10.1103/physrevb.81.125443

Cited by 45 publications

(44 citation statements)

References 23 publications

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“…In addition to the bulk component, four components were required for both spectra to obtain a reasonable fit. One component originated from subsurface Ge atoms at −0.2 eV 42 and the other component (γ ) was located at −0.5 eV. The component γ seems to originate from the Ge-Ge dimer at the residual unoxidized area on the surface 42 and/or can be assigned to the oxide-related component normally observed in the oxidation of Si surfaces.…”

Section: Resultsmentioning

confidence: 92%

“…One component originated from subsurface Ge atoms at −0.2 eV 42 and the other component (γ ) was located at −0.5 eV. The component γ seems to originate from the Ge-Ge dimer at the residual unoxidized area on the surface 42 and/or can be assigned to the oxide-related component normally observed in the oxidation of Si surfaces. 25,[43][44][45] The positions of the components related to suboxide states such as Ge 1+ and Ge 2+ were set to the positions reported by Schmeisser et al 28 Figure 5 shows the results of curve-fitting analysis, and the parameters obtained from the curve-fitting analysis are shown in Table I.…”

Section: Resultsmentioning

confidence: 92%

“…The Lorentzian full width at half maximum (LW) of 150 meV was used for all components according to Eriksson and Uhrberg. 42 The value of the Gaussian full width at half maximum (GW) was separately determined for each single peak profile. In addition to the bulk component, four components were required for both spectra to obtain a reasonable fit.…”

Section: Resultsmentioning

confidence: 99%

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In situ synchrotron radiation photoelectron spectroscopy study of the oxidation of the Ge(100)-2 × 1 surface by supersonic molecular oxygen beams

Yoshigoe

Teraoka

Okada

et al. 2014

The Journal of Chemical Physics

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In situ synchrotron radiation photoelectron spectroscopy was performed during the oxidation of the Ge(100)-2 × 1 surface induced by a molecular oxygen beam with various incident energies up to 2.2 eV from the initial to saturation coverage of surface oxides. The saturation coverage of oxygen on the clean Ge(100) surface was much lower than one monolayer and the oxidation state of Ge was +2 at most. This indicates that the Ge(100) surface is so inert toward oxidation that complete oxidation cannot be achieved with only pure oxygen (O2) gas, which is in strong contrast to Si surfaces. Two types of dissociative adsorption, trapping-mediated and direct dissociation, were confirmed by oxygen uptake measurements depending on the incident energy of O2. The direct adsorption process can be activated by increasing the translational energy, resulting in an increased population of Ge2+ and a higher final oxygen coverage. We demonstrated that hyperthermal O2 beams remarkably promote the room-temperature oxidation with novel atomic configurations of oxides at the Ge(100) surface. Our findings will contribute to the fundamental understanding of oxygen adsorption processes at 300 K from the initial stages to saturated oxidation.

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Section: Resultsmentioning

confidence: 92%

Section: Resultsmentioning

confidence: 92%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

In situ synchrotron radiation photoelectron spectroscopy study of the oxidation of the Ge(100)-2 × 1 surface by supersonic molecular oxygen beams

Yoshigoe

Teraoka

Okada

et al. 2014

The Journal of Chemical Physics

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“…23 The S 0 component has been associated with either the second layer of Si atoms 24 or with one half of the third layer plus the fourth layer of Si atoms. 22 The D and L components are observed on the higher binding energy side of the spectrum with their origin debated in the literature. However, the D component is likely due to surface defects, 22,30 while the L component is related to a surface loss process via interband transitions in surface bands.…”

mentioning

confidence: 98%

“…[15][16][17][18][19] X-ray photoemission has been extensively used to study Si(001), and ample literature exists describing the bulk and surface core-level states both experimentally and theoretically. [20][21][22][23][24][25][26][27][28] At room temperature in vacuum, a clean Si(001) surface exhibits 2 Â 1 reconstruction with buckled asymmetric dimers, 29 giving rise to two surface states of which one is filled (the so-called "up atom" of a dimer) and the other is empty (the "down atom"). Experimentally, the Si 2p core level spectrum of 2 Â 1 Si(001) can be described (fitted) with seven spin-orbit split pairs of surface core-level components.…”

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confidence: 99%

Charge transfer in Sr Zintl template on Si(001)

Choi

Posadas

Seo

et al. 2013

Applied Physics Letters

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The formation of the half monolayer (ML) Sr Zintl template layer on Si(001) is investigated in a combined experimental and theoretical work consisting of in situ reflection high energy electron diffraction, in situ x-ray photoelectron spectroscopy (XPS), and density functional theory. Starting with clean 2 × 1 reconstructed Si(001), we demonstrate that Sr deposition leads to a charge transfer from the metal to the Si substrate resulting in the disappearance of the asymmetry of Si dimers—an essential structural change that enables direct perovskite epitaxy on Si, and likely, other semiconductors. XPS reveals an unexpected shift to higher binding energy of the Si 2p core-level components, including the bulk. This unusual behavior is attributed to final state effects using first principles calculations. As measured by ultraviolet photoelectron spectroscopy, the deposition of 0.5 ML of Sr lowers the work function of the system by 1.35 eV, and is in good agreement with our theoretical calculations.

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A Chemical Route to Monolithic Integration of Crystalline Oxides on Semiconductors

McDaniel

Ngo

Posadas

et al. 2014

Adv Materials Inter

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This work demonstrates the growth of crystalline SrTiO3 (STO) directly on germanium via a chemical method. After thermal deoxidation, the Ge substrate is transferred in vacuo to the deposition chamber where a thin film of STO (2 nm) is deposited by atomic layer deposition (ALD) at 225 °C. Following post‐deposition annealing at 650 °C for 5 min, the STO film becomes crystalline with epitaxial registry to the underlying Ge (001) substrate. Thicker STO films (up to 15 nm) are then grown on the crystalline STO seed layer. The crystalline structure and orientation are confirmed via reflection high‐energy electron diffraction, X‐ray diffraction, and transmission electron microscopy. Electrical measurements of a 15‐nm thick epitaxial STO film on Ge show a large dielectric constant (k ≈ 90), but relatively high leakage current of ≈10 A/cm2 for an applied field of 0.7 MV/cm. To suppress the leakage current, an aluminum precursor is cycled during ALD growth to grow crystalline Al‐doped STO (SrTi1‐xAlxO3‐δ) films. With sufficient Al doping (≈13%), the leakage current decreases by two orders of magnitude for an 8‐nm thick film. The current work demonstrates the potential of ALD‐grown crystalline oxides to be explored for advanced electronic applications, including high‐mobility Ge‐based transistors.

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Surface core-level shifts on clean Si(001) and Ge(001) studied with photoelectron spectroscopy and density functional theory calculations

Abstract: Surface core-level shifts on clean Si(001) and Ge(001) studied with photoelectron spectroscopy and DFT calculations, 2010, Physical Review B.

Cited by 45 publications

References 23 publications

In situ synchrotron radiation photoelectron spectroscopy study of the oxidation of the Ge(100)-2 × 1 surface by supersonic molecular oxygen beams

In situ synchrotron radiation photoelectron spectroscopy study of the oxidation of the Ge(100)-2 × 1 surface by supersonic molecular oxygen beams

Charge transfer in Sr Zintl template on Si(001)

A Chemical Route to Monolithic Integration of Crystalline Oxides on Semiconductors

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