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| 2. |
- Qvarford, M, et al.
(författare)
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Photoemission and x-ray absorption study of superconducting and semiconducting Ba1-xKxBiO3 single crystals
- 1996
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Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 54:9, s. 6700-6707
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Tidskriftsartikel (refereegranskat)abstract
- Semiconducting Ba0.9K0.1BiO3 and superconducting Ba0.6K0.4BiO3 single crystals cleaved in situ have been studied by core level and valence band photoelectron spectroscopy and O K edge x-ray absorption spectroscopy. It was found that the general shape of the valence band spectrum agrees with the shape predicted by band structure calculations, but the intensity near the Fermi level, was lower in the experimental spectrum as compared to the calculated. The O K edge spectra showed that the metallic phase is not related to the presence of doping inducted O 2p holes. This property of Ba1-xKxBiO3 shows that the semiconductor-metal transition of this system is of a different nature than that of the hole doped cuprate high-T-c superconductors. The core level photoemission spectra of the cations showed a small asymmetry for Ba0.9K0.1BiO3. Corresponding spectra for Ba0.6K0.4BiO3 showed a larger asymmetry resulting in a resolved high binding energy shoulder in the Bi 4f spectrum. The origin of this feature is discussed.
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| 5. |
- Girard, R T, et al.
(författare)
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Electronic structure of ZnO(0001) studied by angle-resolved photoelectron spectroscopy
- 1997
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Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 373:2-3, s. 409-417
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Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of the ZnO(0001) surface was studied by angle-resolved photoelectron spectroscopy. The recorded normal emission spectra give information about the Valence band states as well as the Zn 3d states. The dispersions of the four valence bands observed in the (0001) direction were compared with theory and are in good agreement with recent calculations which consider the Zn 3d electrons as part of the valence band. The Zn 3d states are seen to separate into two groups of four and six bands, which show dispersion with k(perpendicular to). This is in agreement with theoretical results but the location of these states were not accurately predicted. The present photoemission results show that they lie around 10.5 eV below E(F). Two surface states were observed on the (0001) surface. One, at 7.5 eV binding energy, was predicted by theory and is interpreted as arising from the ''back-bondings'' of the Zn 4s-O 2p mixed bulk states. The other one at 4.5 eV below E(F), most likely Zn 4p-0 2p derived, was not predicted by theoretical calculations and this is discussed further in the text. (C) 1997 Elsevier Science B.V.
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| 6. |
- Hirschauer, B, et al.
(författare)
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Highly oriented alpha-alumina films grown by pulsed laser deposition
- 1997
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Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 305:1-2, s. 243-247
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Tidskriftsartikel (refereegranskat)abstract
- Highly oriented thin films of alpha-alumina have been grown by pulsed laser deposition on Si(lll). The influence of the substrate temperature on the film growth was studied by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (MID). Ablation at temperatures between room temperature and 850 degrees C gave rise to incorporated crystalline aluminium (Al), while the stoichiometric and highly oriented alpha-Al2O3 films were obtained only at 850 degrees C. The XRD rocking curve measurements of the ablated films showed the full-width-at-half-maximum (FWHM) Of 0.2 degrees. Further annealing at 1000 degrees C in air for 26 h slightly improved out-of-plane orientation. (C) 1997 Elsevier Science S.A.
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| 7. |
- Qvarford, M, et al.
(författare)
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Doping dependence of the O 1s is core-level photoemission in bi-Sr-Ca-Cu-O superconductors
- 1996
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Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 53:22, s. 14753-14756
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Tidskriftsartikel (refereegranskat)abstract
- The O 1s core level of three different Bi-Sr-Ca-Cu-O superconductors has been studied by means of high-resolution x-ray-photoelectron spectroscopy (XPS) and x-ray absorption spectroscopy (XAS). The O 1a XPS spectra could be decomposed into three components that were unambiguously assigned to the emission from the three different oxide layers in the crystal structure. These are, in order of increasing binding energy, Cu-O-2, Sr-O, and Bi-O. Furthermore, the component assigned to the Cu-O-2 layers exhibits a shift which depends on the hole doping as monitored by the XAS spectra.
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| 8. |
- Qvarford, M, et al.
(författare)
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Doping dependence of the O 1s is core-level photoemission in bi-Sr-Ca-Cu-O superconductors
- 1996
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Ingår i: PHYSICAL REVIEW B-CONDENSED MATTER. - : AMER INST PHYSICS. - 0163-1829. ; 53:22, s. 14753-14756
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The O 1s core level of three different Bi-Sr-Ca-Cu-O superconductors has been studied by means of high-resolution x-ray-photoelectron spectroscopy (XPS) and x-ray absorption spectroscopy (XAS). The O 1a XPS spectra could be decomposed into three component
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