| 1. |
- Göthelid, M., et al.
(författare)
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Adatom and rest-atom contributions in Ge(111)c(2×8) and Ge(111)-Sn(7×7) core-level spectra
- 1993
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Ingår i: Physical Review B. - 0163-1829. ; 48:3, s. 2012-2015
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Tidskriftsartikel (refereegranskat)abstract
- We have identified the adatom contribution in the Ge 3d core-level spectra from the clean Ge(111)c(2×8) surface, shifted 0.17 eV to higher binding energy compared to the bulk. This adatom component vanishes in the Ge(111)-Sn(7×7) surface core-level spectra where Sn occupies the adatom site. Moreover we report the observation of an earlier proposed difference between the rest atoms in the c(2×8) structure, and also a shift to lower binding energy for the rest atoms in both structures studied. © 1993 The American Physical Society.
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| 2. |
- Göthelid, M., et al.
(författare)
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Sn-induced surface reconstructions on the Ge(111) surface studied with scanning tunneling microscopy
- 1992
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Ingår i: Surface Science. - 0039-6028. ; 271:3, s. L357-L361
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Tidskriftsartikel (refereegranskat)abstract
- Scanning tunneling microscopy (STM) has been used to study different Sn induced reconstructions on the Ge(111) surface; namely the (7 × 7), (5 × 5) and ( 3 × 3) R30° structures. The first two have been confirmed to be of the dimer adatom stacking faults (DAS) type with adatoms mainly being Sn. The ( 3 × 3)R30° superstructure was found at different Sn depositions. At 0.4 monolayer (ML) Sn coverage a homogeneous Sn adatom layer is adsorbed on the(1 × 1) surface in threefold sites directly over second-layer atoms (T4), while at low coverage, 0.1 ML, the top layer is a mixture of Sn and Ge atoms. We also propose the chemical identities of the different atoms seen in the STM images as related to their apparent height. © 1992.
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| 3. |
- Hammar, M., et al.
(författare)
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Initial growth of silver on Ge(111) studied by scanning tunneling microscopy
- 1993
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Ingår i: Physical Review B. - 0163-1829. ; 47:23, s. 15669-15674
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Tidskriftsartikel (refereegranskat)abstract
- Scanning tunneling microscopy (STM) has been used to study the Ge(111) surface after submonolayer depositions of Ag. At the lowest coverages a (4×4) reconstruction, with small insets of a (3×1) edge structure, is observed. Based on the STM images we propose a mixed Ag and Ge adatom structure for the (4×4) reconstruction, in which the adatoms have local (1×1) and (2×2) arrangements corresponding to a Ag coverage of 6/16 monolayers. The (3×1) structure appears to have a configuration similar to the Si(111)/Ag-(3×1) reconstruction, although in this case it has a much more limited extension, restricted to a few unit cells in the near vicinity of step edges and phase boundaries. At higher coverages, after the completion of a full (4×4)/(3×1) surface, a (3 × 3) R30°structure appears showing STM images similar to those previously published for the Si(111)/Ag system. © 1993 The American Physical Society.
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| 4. |
- Hammar, M., et al.
(författare)
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Morphology and atomic structure of the sputtered and annealed Mo3Si and Cr3Si (110) surfaces
- 1994
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Ingår i: Physical Review B. - 0163-1829. ; 50:23, s. 17639-17642
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Tidskriftsartikel (refereegranskat)abstract
- Scanning tunneling microscopy was used to study the sputtered and annealed (110) surfaces of Mo3Si and Cr3Si. Both surfaces show extended and atomically flat terraces, but in the case of Mo3Si there is also a uniform distribution of Mo crystallites. This difference in morphology is discussed in terms of different preferential sputtering effects. In both cases, measured step heights show that the ideally bulk-truncated surfaces are either purely Si or metal terminated. Atomically resolved images suggest that the Mo3Si surface is Si terminated, but although no atomic resolution could be obtained for the Cr3Si surface, there are indications that this surface is instead metal terminated. © 1994 The American Physical Society.
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| 5. |
- Hammar, Mattias, 1961-, et al.
(författare)
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Scanning tunnelling microscopy studies of Pt80Fe 20(110)
- 1993
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Ingår i: Journal of Physics: Condensed Matter. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 5:18, s. 2837-2842
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Tidskriftsartikel (refereegranskat)abstract
- Results of scanning tunnelling microscopy (STM) show that two different kinds of surface structures coexist on the (110) surface of Pt 80Fe20. The predominant structure corresponds well to the missing row type (1*2) reconstruction previously observed on, for example Pt(110), whereas the minority domains show a faintly buckled structure with approximately (1*1) geometry. Based on the STM images, the authors propose that the two domains have different surface chemical compositions and correspond to two different metallurgical phases known for the PtFe system at this composition.
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| 6. |
- Hammar, M., et al.
(författare)
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Surface atomic structure of reconstructed VC0.8(111) studied with scanning tunneling microscopy
- 1992
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Ingår i: Physical Review B. - 0163-1829. ; 45:11, s. 6118-6123
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Tidskriftsartikel (refereegranskat)abstract
- Scanning tunneling microscopy has been performed on the reconstructed polar surface of substoichiometric VC0.80(111). A mixture of (8×1) and (3 × 3) R30°reconstructed areas was found. The (8×1) periodicity could be determined to be the result of a square-lattice surface layer superimposed on the hexagonal substrate. As this square lattice must have its origin in strong and directed in-plane bonds with the relatively large length of about 2.9, it can be deduced to consist of vanadium atoms. Lateral positions of these vanadium surface atoms with respect to the substrate are suggested from the measured surface corrugation. The (3 × 3) R30°structure was found in small triangular areas which can, due to the measured step heights between the two reconstructions, be believed to be carbon terminated. The occurrence of a reconstructed surface with a reduced atomic concentration is in contrast to what is known for TiC(111) and NbC(111), both having stable (1×1) surfaces. A qualitative explanation for this difference is suggested. © 1992 The American Physical Society.
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| 7. |
- Le Lay, G., et al.
(författare)
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STM and synchrotron radiation studies of "prototypical" metal{plus 45 degree rule}semiconductor systems
- 1994
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Ingår i: Surface Science. - 0039-6028. ; 307-309:PART A, s. 280-294
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Tidskriftsartikel (refereegranskat)abstract
- Since the origin of surface science noble metal{plus 45 degree rule}elemental semiconductor couples have been considered as "prototypical" systems. After three decades of research their structural and electronic properties remain an intriguing maze despite recent advances made, especially thanks to the development of the near-field microscopies and the extensive use of synchrotron radiation in surface crystallography and in high-resolution photoelectron spectroscopy. In the last few years, lead, as a replacement inert metal, has nearly gained the pole position in the display of exotic behaviour. This paper gives a flavour of this mystery story and highlights some puzzling questions. © 1994.
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| 8. |
- Törnevik, C., et al.
(författare)
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Adsorption of Sn onSi(111)7 × 7 : reconstructions in the monolayer regime
- 1994
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Ingår i: Surface Science. - 0039-6028. ; 314:2, s. 179-187
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Tidskriftsartikel (refereegranskat)abstract
- Different monolayer phases of Sn on Si(111)7 × 7 have been studied by means of scanning tunneling microscopy (STM), core-level photoelectron spectroscopy (XPS), and Rutherford backscattering spectrometry (RBS). The STM results show that 3 × 3 reconstructions are obtained for room-temperature deposition of 1 3 ML of Sn followed by sample annealing in a broad temperature range. A T4 Sn adatom 3 ×3 phase is formed for temperatures between 500 and 800°C, with a concentration of defects that is strongly dependent on the temperature and which is as high as 25% for the lowest temperatures. Above 825°C a second 3×3 adatom reconstruction is formed, a mosaic-like phase with a 1:1 mixture of Si and Sn atoms in T4 positions. The results from investigations of the higher coverage 2 3 × 2 3 reconstruction by XPS and RBS support the theory that this phase is a two-layer epitaxial Sn structure with all Si(111) dangling bonds saturated. The Sn coverage for this phase was determined to be between 1 and 1.2 ML. © 1994.
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