Ge/Si Quantum Dots Superlattices Grown at Different Temperatures and Characterized by Raman Spectroscopy and Capacitance Measurements
Ge/Si heterostructures with Ge self-assembled quantum dots (SAQDs) grown at various temperatures by molecular beam epitaxy were investigated using resonant Raman spectroscopy and capacitance measurements. The occurrence of quantum confinement effects was confirmed by both techniques. For the structu...
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| Format: | Article |
| Language: | English |
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Wiley
2012-01-01
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| Series: | Advances in Condensed Matter Physics |
| Online Access: | http://dx.doi.org/10.1155/2012/176053 |
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| author | A. D. Rodrigues A. J. Chiquito G. Zanelatto A. G. Milekhin A. I. Nikiforov V. V. Ulyanov O. P. Pchelyakov D. R. T. Zahn J. C. Galzerani |
| author_facet | A. D. Rodrigues A. J. Chiquito G. Zanelatto A. G. Milekhin A. I. Nikiforov V. V. Ulyanov O. P. Pchelyakov D. R. T. Zahn J. C. Galzerani |
| author_sort | A. D. Rodrigues |
| collection | DOAJ |
| description | Ge/Si heterostructures with Ge self-assembled quantum dots (SAQDs) grown at various temperatures by molecular beam epitaxy were investigated using resonant Raman spectroscopy and capacitance measurements. The occurrence of quantum confinement effects was confirmed by both techniques. For the structures grown at low temperatures (300−400°C), the SAQDs optical phonon wavenumbers decrease as the Raman excitation energy is increased; this is an evidence of the scattering sensitivity to the size of the SAQDs and to the inhomogeneity in their sizes. However, the opposite behavior is observed for the SAQDs grown at higher temperatures, as a consequence of the competition between the phonon localization and internal mechanical stress effects. The E1 electronic transition of the Ge in the SAQDs was found to be shifted towards higher energies as compared to bulk Ge, due to biaxial compressive stress and to the electronic confinement effect present in the structures. The intermixing of Si atoms in the quantum dots was found to be much more significant for the sample grown at higher temperatures. The capacitance measurements, besides confirming the existence of the dots in these structures, showed that the deepest Ge layers lose their 0D signature as the growth temperature increases. |
| format | Article |
| id | doaj-art-63fbb40c605341a1816b273560425ca1 |
| institution | OA Journals |
| issn | 1687-8108 1687-8124 |
| language | English |
| publishDate | 2012-01-01 |
| publisher | Wiley |
| record_format | Article |
| series | Advances in Condensed Matter Physics |
| spelling | doaj-art-63fbb40c605341a1816b273560425ca12025-08-20T02:23:53ZengWileyAdvances in Condensed Matter Physics1687-81081687-81242012-01-01201210.1155/2012/176053176053Ge/Si Quantum Dots Superlattices Grown at Different Temperatures and Characterized by Raman Spectroscopy and Capacitance MeasurementsA. D. Rodrigues0A. J. Chiquito1G. Zanelatto2A. G. Milekhin3A. I. Nikiforov4V. V. Ulyanov5O. P. Pchelyakov6D. R. T. Zahn7J. C. Galzerani8Department of Physics, Federal University of São Carlos, CP 676, 13565-905 São Carlos, SP, BrazilDepartment of Physics, Federal University of São Carlos, CP 676, 13565-905 São Carlos, SP, BrazilDepartment of Physics, Federal University of São Carlos, CP 676, 13565-905 São Carlos, SP, BrazilInstitute of Semiconductor Physics, Novosibirsk 630090, RussiaInstitute of Semiconductor Physics, Novosibirsk 630090, RussiaInstitute of Semiconductor Physics, Novosibirsk 630090, RussiaInstitute of Semiconductor Physics, Novosibirsk 630090, RussiaInstitut für Physik, Technische Universität Chemnitz, 09107 Chemnitz, GermanyDepartment of Physics, Federal University of São Carlos, CP 676, 13565-905 São Carlos, SP, BrazilGe/Si heterostructures with Ge self-assembled quantum dots (SAQDs) grown at various temperatures by molecular beam epitaxy were investigated using resonant Raman spectroscopy and capacitance measurements. The occurrence of quantum confinement effects was confirmed by both techniques. For the structures grown at low temperatures (300−400°C), the SAQDs optical phonon wavenumbers decrease as the Raman excitation energy is increased; this is an evidence of the scattering sensitivity to the size of the SAQDs and to the inhomogeneity in their sizes. However, the opposite behavior is observed for the SAQDs grown at higher temperatures, as a consequence of the competition between the phonon localization and internal mechanical stress effects. The E1 electronic transition of the Ge in the SAQDs was found to be shifted towards higher energies as compared to bulk Ge, due to biaxial compressive stress and to the electronic confinement effect present in the structures. The intermixing of Si atoms in the quantum dots was found to be much more significant for the sample grown at higher temperatures. The capacitance measurements, besides confirming the existence of the dots in these structures, showed that the deepest Ge layers lose their 0D signature as the growth temperature increases.http://dx.doi.org/10.1155/2012/176053 |
| spellingShingle | A. D. Rodrigues A. J. Chiquito G. Zanelatto A. G. Milekhin A. I. Nikiforov V. V. Ulyanov O. P. Pchelyakov D. R. T. Zahn J. C. Galzerani Ge/Si Quantum Dots Superlattices Grown at Different Temperatures and Characterized by Raman Spectroscopy and Capacitance Measurements Advances in Condensed Matter Physics |
| title | Ge/Si Quantum Dots Superlattices Grown at Different Temperatures and Characterized by Raman Spectroscopy and Capacitance Measurements |
| title_full | Ge/Si Quantum Dots Superlattices Grown at Different Temperatures and Characterized by Raman Spectroscopy and Capacitance Measurements |
| title_fullStr | Ge/Si Quantum Dots Superlattices Grown at Different Temperatures and Characterized by Raman Spectroscopy and Capacitance Measurements |
| title_full_unstemmed | Ge/Si Quantum Dots Superlattices Grown at Different Temperatures and Characterized by Raman Spectroscopy and Capacitance Measurements |
| title_short | Ge/Si Quantum Dots Superlattices Grown at Different Temperatures and Characterized by Raman Spectroscopy and Capacitance Measurements |
| title_sort | ge si quantum dots superlattices grown at different temperatures and characterized by raman spectroscopy and capacitance measurements |
| url | http://dx.doi.org/10.1155/2012/176053 |
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