Metal-insulator transition in Si(111)-(4 × 1)/(8 × 2)-In studied by optical spectroscopy
| Autor: | E. Speiser, Stefan Martin Wippermann, W. Richter, M. Gensch, Norbert Esser, Christoph Cobet, John F. McGilp, Karsten Hinrichs, Karsten Fleischer, Friedhelm Bechstedt, Wolf Gero Schmidt, S. Chandola |
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| Rok vydání: | 2010 |
| Předmět: |
Phase transition
Condensed matter physics Chemistry Condensed Matter Physics Molecular physics Settore FIS/03 - Fisica della Materia Electronic Optical and Magnetic Materials symbols.namesake Ab initio quantum chemistry methods Molecular vibration symbols Local-density approximation Metal–insulator transition Anisotropy Spectroscopy Raman spectroscopy |
| Zdroj: | physica status solidi (b). 247:2033-2039 |
| ISSN: | 1521-3951 0370-1972 |
| Popis: | Measurements of the surface vibrational modes and optical response of Si(111)-(4 x 1)/(8 x 2)-In are compiled and a comparison to ab initio calculations performed within DFT-LDA formalism is given. Surface resonant Raman spectroscopy allows identifying a number of surface phonons with high spectral precision. The phase transition of the (4 x 1)-(8 x 2) surface structure is found to be accompanied by characteristic changes of the surface phonons, which are discussed with respect to various structural models suggested. The optical anisotropy of the (8 x 2) phase shows that the anisotropic Drude tail of the (4 x 1) phase is replaced by two peaks at 0.50 and 0.72 eV. The spectroscopic signatures of the (4 x 1) and (8 x 2) phases agree with a metal-insulator transition. The mid-IR-anisotropic optical response of the insulating (8 x 2) phase is interpreted in terms of electronic single particle excitations between surface electronic bands related to the In-nanowire surface. Comparison of the measured optical transitions with DFT ab initio calculations for the hexagon model and the trimer model of the (8 x 2) structure shows evidence for the existence of the hexagon structure. |
| Databáze: | OpenAIRE |
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