| 1. |
- GOTHELID, M, et al.
(author)
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GEOMETRY OF THE GE(111)-AU(ROOT-3X-ROOT-3)R 30-DEGREES RECONSTRUCTION
- 1994
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In: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 50:7, s. 4470-4475
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Journal article (peer-reviewed)abstract
- A structure model for the Ge(111)-Au(root 3X root 3)R30 degrees surface reconstruction is proposed based on scanning tunneling microscopy (STM) and photoelectron spectroscopy on the Ge 3d and Au 4f core lines. The basic unit is a Au3Ge molecule binding in one-third of the T-1 substrate sites with a gold trimer pointing out of the surface. This leaves two-thirds of a monolayer of unoccupied T-1 sites which make up a hexagonal honeycomb pattern. Two types of STM images have been obtained which are explained within this model, where either the trimers or the substrate Ge atoms are probed depending on the specific tip conditions in combination with the sample bias voltage. Furthermore, small insets of a metallic (1X1) structure are found at low gold coverage together with a distorted (2X2) surface structure.
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| 2. |
- Göthelid, M., et al.
(author)
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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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In: Physical Review B. - 0163-1829. ; 48:3, s. 2012-2015
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Journal article (peer-reviewed)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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| 3. |
- Le Lay, G., et al.
(author)
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STM and synchrotron radiation studies of "prototypical" metal{plus 45 degree rule}semiconductor systems
- 1994
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In: Surface Science. - 0039-6028. ; 307-309:PART A, s. 280-294
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Journal article (peer-reviewed)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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| 4. |
- LELAY, G, et al.
(author)
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STM AND SYNCHROTRON-RADIATION STUDIES OF PROTOTYPICAL METAL-SEMICONDUCTOR SYSTEMS
- 1994
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In: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 307, s. 280-294
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Journal article (peer-reviewed)abstract
- Since the origin of surface science noble metal/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 ''tensive 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.
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| 5. |
- TORNEVIK, C, et al.
(author)
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ADSORPTION OF SN ON SI(111)7X7 - RECONSTRUCTIONS IN THE MONOLAYER REGIME
- 1994
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In: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 314:2, s. 179-187
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Journal article (peer-reviewed)abstract
- Different monolayer phases of Sn on Si(111)7 x 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 square-root 3 x square-root 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 square-root 3 x square-root 3 phase is formed for temperatures between 500 and 800-degrees-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-degrees-C a second square-root 3 x square-root 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 square-root 3 x 2 square-root 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.
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| 6. |
- Törnevik, C., et al.
(author)
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Adsorption of Sn onSi(111)7 × 7 : reconstructions in the monolayer regime
- 1994
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In: Surface Science. - 0039-6028. ; 314:2, s. 179-187
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Journal article (peer-reviewed)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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| 7. |
- Vaitkus, J., et al.
(author)
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Scanning tunneling microscopy of CdSe single crystal cleaved and "real" surface
- 1994
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In: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248. ; 138:1-4, s. 545-549
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Journal article (peer-reviewed)abstract
- Ultrahigh vacuum-cleaved and as-grown surfaces of CdSe single crystals were investigated by scanning tunneling microscopy. The single crystals were grown by Reynolds-Green method. Striations and terrace-step structure have been found. The surface atomic geometry was found and investigated. The (1120) face geometry (structure formed by elementary cell of 0.75 × 0.7 nm2) as well as other type structures (e.g., 2.1 × 0.75 nm2 elementary cell) have been determined. The variations of the band gap at the surface have been found. The band values in the range 2.0-2.6 eV on a cleaved surface and 1.1-2.0 eV on an as-grown surface were measured and explained as being the influence of surface relaxation and gas adsorption. © 1994.
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| 8. |
- GOTHELID, M, et al.
(author)
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FORMATION OF AN IODINE ZIGZAG CHAIN C(2X4) RECONSTRUCTION ON THE GE(111) SURFACE
- 1994
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In: Microscopy Microanalysis Microstructures. - : EDP Sciences. - 1154-2799. ; 5:4-6, s. 277-282
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Journal article (peer-reviewed)abstract
- Room temperature adsorption of I-2 on the Ge(lll) surface is found to break the initial c(2 x 8) adatom reconstruction as iodine preferentially occupies the on top substrate site, breaks the backbonds between the adatom and the substrate and thus removes the Ge adatoms. As this process continues a c(2 x 4), and modifications thereof, reconstruction is formed consisting of chains of I-2 molecules bound in almost T-1 sites with a I-I bond length of 3.6 Angstrom.
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| 9. |
- GOTHELID, M, et al.
(author)
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SN-INDUCED SURFACE RECONSTRUCTIONS ON THE GE(111) SURFACE STUDIED WITH SCANNING TUNNELING MICROSCOPY
- 1992
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In: Surface Science. - 0039-6028 .- 1879-2758. ; 271:3, s. L357-L361
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Journal article (peer-reviewed)abstract
- Scanning tunneling microscopy (STM) has been used to study different Sn induced reconstructions on the Ge(111) surface; namely the (7 x 7), (5 x 5) and (square-root 3 x square-root 3)R30-degrees structures. The first two have been confirmed to be of the dimer adatom stacking fault (DAS) type with adatoms mainly being Sn. The (square-root 3 x square-root 3)R30-degrees superstructure was found at different Sn depositions. At 0.4 monolayer (ML) Sn coverage a homogeneous Sn adatom layer is adsorbed on the (1 x 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.
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| 10. |
- Göthelid, M., et al.
(author)
-
Sn-induced surface reconstructions on the Ge(111) surface studied with scanning tunneling microscopy
- 1992
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In: Surface Science. - 0039-6028. ; 271:3, s. L357-L361
-
Journal article (peer-reviewed)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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