Atomic-scale study of the amorphous-to-crystalline phase transition mechanism in GeTe thin films
Abstract The underlying mechanism driving the structural amorphous-to-crystalline transition in Group VI chalcogenides is still a matter of debate even in the simplest GeTe system. We exploit the extreme sensitivity of 57Fe emission Mössbauer spectroscopy, following dilute implantation of 57Mn (T½ =...
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Nature Portfolio
2017-08-01
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| Series: | Scientific Reports |
| Online Access: | https://doi.org/10.1038/s41598-017-08275-5 |
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| author | R. Mantovan R. Fallica A. Mokhles Gerami T. E. Mølholt C. Wiemer M. Longo H. P. Gunnlaugsson K. Johnston H. Masenda D. Naidoo M. Ncube K. Bharuth-Ram M. Fanciulli H. P. Gislason G. Langouche S. Ólafsson G. Weyer |
| author_facet | R. Mantovan R. Fallica A. Mokhles Gerami T. E. Mølholt C. Wiemer M. Longo H. P. Gunnlaugsson K. Johnston H. Masenda D. Naidoo M. Ncube K. Bharuth-Ram M. Fanciulli H. P. Gislason G. Langouche S. Ólafsson G. Weyer |
| author_sort | R. Mantovan |
| collection | DOAJ |
| description | Abstract The underlying mechanism driving the structural amorphous-to-crystalline transition in Group VI chalcogenides is still a matter of debate even in the simplest GeTe system. We exploit the extreme sensitivity of 57Fe emission Mössbauer spectroscopy, following dilute implantation of 57Mn (T½ = 1.5 min) at ISOLDE/CERN, to study the electronic charge distribution in the immediate vicinity of the 57Fe probe substituting Ge (FeGe), and to interrogate the local environment of FeGe over the amorphous-crystalline phase transition in GeTe thin films. Our results show that the local structure of as-sputtered amorphous GeTe is a combination of tetrahedral and defect-octahedral sites. The main effect of the crystallization is the conversion from tetrahedral to defect-free octahedral sites. We discover that only the tetrahedral fraction in amorphous GeTe participates to the change of the FeGe-Te chemical bonds, with a net electronic charge density transfer of ~ 1.6 e/a0 between FeGe and neighboring Te atoms. This charge transfer accounts for a lowering of the covalent character during crystallization. The results are corroborated by theoretical calculations within the framework of density functional theory. The observed atomic-scale chemical-structural changes are directly connected to the macroscopic phase transition and resistivity switch of GeTe thin films. |
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| issn | 2045-2322 |
| language | English |
| last_indexed | 2024-12-19T04:15:32Z |
| publishDate | 2017-08-01 |
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| spelling | doaj.art-8b8010c07dc04e4ba12f057b6f4b397d2022-12-21T20:36:18ZengNature PortfolioScientific Reports2045-23222017-08-017111210.1038/s41598-017-08275-5Atomic-scale study of the amorphous-to-crystalline phase transition mechanism in GeTe thin filmsR. Mantovan0R. Fallica1A. Mokhles Gerami2T. E. Mølholt3C. Wiemer4M. Longo5H. P. Gunnlaugsson6K. Johnston7H. Masenda8D. Naidoo9M. Ncube10K. Bharuth-Ram11M. Fanciulli12H. P. Gislason13G. Langouche14S. Ólafsson15G. Weyer16Laboratorio MDM, IMM-CNRLaboratorio MDM, IMM-CNRPhysics Department, ISOLDE/CERNPhysics Department, ISOLDE/CERNLaboratorio MDM, IMM-CNRLaboratorio MDM, IMM-CNRScience Institute, University of IcelandPhysics Department, ISOLDE/CERNSchool of Physics, University of the WitwatersrandSchool of Physics, University of the WitwatersrandSchool of Physics, University of the WitwatersrandDurban University of TechnologyLaboratorio MDM, IMM-CNRScience Institute, University of IcelandKU Leuven, Instituut voor Kern-en Stralings FysikaScience Institute, University of IcelandDepartment of Physics and Astronomy, Aarhus UniversityAbstract The underlying mechanism driving the structural amorphous-to-crystalline transition in Group VI chalcogenides is still a matter of debate even in the simplest GeTe system. We exploit the extreme sensitivity of 57Fe emission Mössbauer spectroscopy, following dilute implantation of 57Mn (T½ = 1.5 min) at ISOLDE/CERN, to study the electronic charge distribution in the immediate vicinity of the 57Fe probe substituting Ge (FeGe), and to interrogate the local environment of FeGe over the amorphous-crystalline phase transition in GeTe thin films. Our results show that the local structure of as-sputtered amorphous GeTe is a combination of tetrahedral and defect-octahedral sites. The main effect of the crystallization is the conversion from tetrahedral to defect-free octahedral sites. We discover that only the tetrahedral fraction in amorphous GeTe participates to the change of the FeGe-Te chemical bonds, with a net electronic charge density transfer of ~ 1.6 e/a0 between FeGe and neighboring Te atoms. This charge transfer accounts for a lowering of the covalent character during crystallization. The results are corroborated by theoretical calculations within the framework of density functional theory. The observed atomic-scale chemical-structural changes are directly connected to the macroscopic phase transition and resistivity switch of GeTe thin films.https://doi.org/10.1038/s41598-017-08275-5 |
| spellingShingle | R. Mantovan R. Fallica A. Mokhles Gerami T. E. Mølholt C. Wiemer M. Longo H. P. Gunnlaugsson K. Johnston H. Masenda D. Naidoo M. Ncube K. Bharuth-Ram M. Fanciulli H. P. Gislason G. Langouche S. Ólafsson G. Weyer Atomic-scale study of the amorphous-to-crystalline phase transition mechanism in GeTe thin films Scientific Reports |
| title | Atomic-scale study of the amorphous-to-crystalline phase transition mechanism in GeTe thin films |
| title_full | Atomic-scale study of the amorphous-to-crystalline phase transition mechanism in GeTe thin films |
| title_fullStr | Atomic-scale study of the amorphous-to-crystalline phase transition mechanism in GeTe thin films |
| title_full_unstemmed | Atomic-scale study of the amorphous-to-crystalline phase transition mechanism in GeTe thin films |
| title_short | Atomic-scale study of the amorphous-to-crystalline phase transition mechanism in GeTe thin films |
| title_sort | atomic scale study of the amorphous to crystalline phase transition mechanism in gete thin films |
| url | https://doi.org/10.1038/s41598-017-08275-5 |
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