| 1. |
- GOTHELID, M, et al.
(author)
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ADSORPTION OF TIN ON THE GE(111)-C(2X8) SURFACE STUDIED WITH SCANNING-TUNNELING-MICROSCOPY AND PHOTOELECTRON-SPECTROSCOPY
- 1995
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In: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 328:1-2, s. 80-94
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Journal article (peer-reviewed)abstract
- The growth and epitaxy of Sn on Ge(111) have been investigated using scanning tunneling microscopy (STM), low energy electron diffraction (LEED) and core level photoelectron spectroscopy for coverages ranging from 0.4 monolayers (ML) to above the critical coverage at 1.6 ML. At the lowest coverage a (root 3 X root 3)R30 degrees reconstruction is formed at an annealing temperature of 250-300 degrees C while an annealing above 500 degrees C creates a dimer-adatom-stacking fault (DAS) (7 X 7) structure. In the (7 X 7) structure we argue that Sn occupies both adatom and dimer sites. A previously suggested difference in the (root 3 X root 3)R30 degrees reconstruction at different coverages could not be revealed in our STM images and it seems likely that the structure is the same both at 0.4 and 0.7 ML Sn coverage. We also report the observation of a new superstructure, a (4 X root 7) reconstruction in the submonolayer regime, which appears as a minority structure in disordered regions adjacent to a (5 X 5) DAS structure, Finally in the post-monolayer region a (3 X 2 root 3) structure, surrounded by vast areas of an amorphous tin overlayer, has been imaged by STM. As the coverage was increased, the amorphous layer completely covered the ordered (3 X 2 root 3) phase, which still could be observed in LEED. Additional room temperature deposition of Sn deteriorated the fractional order LEED spots presumably due to indiffusion of Sn from the interface as the critical coverage was surpassed.
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| 2. |
- GOTHELID, M, et al.
(author)
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METAL-SEMICONDUCTOR FLUCTUATION IN THE SN ADATOMS IN THE SI(111)-SN AND GE(111)-SN (ROOT-3X-ROOT-3)R30-DEGREES RECONSTRUCTIONS
- 1995
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In: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 52:20, s. 14352-14355
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Journal article (peer-reviewed)abstract
- The two components of the Sn 4d core level in the Si(111)-Sn and Ge(111)-Sn. (root 3 X root 3)R30 degrees structures are proposed to arise from semiconductor-metal fluctuations in the Sn adatom layer. Adsorption of potassium on the Si(111)-Sn (root 3 X root 3)R30 degrees surface suppresses the metallic component and shifts the tin into a purely semiconducting phase with a filled dangling bond state.
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| 3. |
- GREHK, TM, et al.
(author)
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ADSORPTION OF POTASSIUM ON THE SI(111)ROOT-3X-ROOT-3R30-DEGREES - B-SURFACE - OBSERVATION OF AN INSULATING SURFACE AT SUBMONOLAYER COVERAGE
- 1993
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In: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 47:20, s. 13887-13890
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Journal article (peer-reviewed)abstract
- The Si(111) square-root 3 X square-root 3R 30-degrees:B surface with submonolayer coverages of potassium has been studied with angle-resolved photoelectron spectroscopy. Deposition of potassium leads to the formation of a state 0.7 eV below the Fermi level. The energy position of this state showed only a minor dependence on the actual potassium coverage and the state displayed a small dispersion of 0.1 eV when probed along the GAMMABAR-MBAR' direction in the square-root 3 X square-root 3R 30-degrees-surface Brillouin zone. These results support the idea that a mainly covalent bonding exists between the potassium atoms and the Si surface.
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| 4. |
- GREHK, TM, et al.
(author)
-
CLEAN AND CS-EXPOSED SI(111)ROOT-3X-ROOT-3-B SURFACE STUDIED WITH HIGH-RESOLUTION PHOTOEMISSION
- 1995
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 52:15, s. 11165-11171
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Journal article (peer-reviewed)abstract
- Both the clean and Cs-exposed Si(111)root 3X root 3R30 degrees:B surfaces have been investigated by high-resolution photoemission. In the spectra from the Si 2p level, contributions were identified from the bulk, the adatoms plus the first layer, the second and 2/3 ML of the third-layer atoms not binding to the B atoms, and, finally, the 1/3 ML of third-layer atoms binding to the boron atoms. The interaction between the Cs atoms and the surface is found to be dependent on the coverage. At low coverages the geometric and electronic structure of the Si(111)root 3X root 3R30 degrees:B interface is only to a minor degree affected by the presence of Cs on the surface. At high coverage the Cs atoms react with the surface and alter the binding configuration of the Si adatoms.
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| 5. |
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