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Atomic-scale study of the amorphous-to-crystalline phase transition mechanism in GeTe thin films

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 m...

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Autores principales: Mantovan, R., Fallica, R., Mokhles Gerami, A., Mølholt, T. E., Wiemer, C., Longo, M., Gunnlaugsson, H. P., Johnston, K., Masenda, H., Naidoo, D., Ncube, M., Bharuth-Ram, K., Fanciulli, M., Gislason, H. P., Langouche, G., Ólafsson, S., Weyer, G.
Publicado: 2017
Acceso en línea:https://dx.doi.org/10.1038/s41598-017-08275-5
http://cds.cern.ch/record/2280772
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author Mantovan, R.
Fallica, R.
Mokhles Gerami, A.
Mølholt, T. E.
Wiemer, C.
Longo, M.
Gunnlaugsson, H. P.
Johnston, K.
Masenda, H.
Naidoo, D.
Ncube, M.
Bharuth-Ram, K.
Fanciulli, M.
Gislason, H. P.
Langouche, G.
Ólafsson, S.
Weyer, G.
author_facet Mantovan, R.
Fallica, R.
Mokhles Gerami, A.
Mølholt, T. E.
Wiemer, C.
Longo, M.
Gunnlaugsson, H. P.
Johnston, K.
Masenda, H.
Naidoo, D.
Ncube, M.
Bharuth-Ram, K.
Fanciulli, M.
Gislason, H. P.
Langouche, G.
Ólafsson, S.
Weyer, G.
author_sort Mantovan, R.
collection CERN
description 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.
id cern-2280772
institution Organización Europea para la Investigación Nuclear
publishDate 2017
record_format invenio
spelling cern-22807722022-07-08T07:11:39Zdoi:10.1038/s41598-017-08275-5http://cds.cern.ch/record/2280772Mantovan, R.Fallica, R.Mokhles Gerami, A.Mølholt, T. E.Wiemer, C.Longo, M.Gunnlaugsson, H. P.Johnston, K.Masenda, H.Naidoo, D.Ncube, M.Bharuth-Ram, K.Fanciulli, M.Gislason, H. P.Langouche, G.Ólafsson, S.Weyer, G.Atomic-scale study of the amorphous-to-crystalline phase transition mechanism in GeTe thin filmsThe 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.oai:cds.cern.ch:22807722017
spellingShingle Mantovan, R.
Fallica, R.
Mokhles Gerami, A.
Mølholt, T. E.
Wiemer, C.
Longo, M.
Gunnlaugsson, H. P.
Johnston, K.
Masenda, H.
Naidoo, D.
Ncube, M.
Bharuth-Ram, K.
Fanciulli, M.
Gislason, H. P.
Langouche, G.
Ólafsson, S.
Weyer, G.
Atomic-scale study of the amorphous-to-crystalline phase transition mechanism in GeTe thin films
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://dx.doi.org/10.1038/s41598-017-08275-5
http://cds.cern.ch/record/2280772
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