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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Autores principales:	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
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2017
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/8b8010c07dc04e4ba12f057b6f4b397d
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spelling	oai:doaj.org-article:8b8010c07dc04e4ba12f057b6f4b397d2021-12-02T16:06:43ZAtomic-scale study of the amorphous-to-crystalline phase transition mechanism in GeTe thin films10.1038/s41598-017-08275-52045-2322https://doaj.org/article/8b8010c07dc04e4ba12f057b6f4b397d2017-08-01T00:00:00Zhttps://doi.org/10.1038/s41598-017-08275-5https://doaj.org/toc/2045-2322Abstract 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.R. MantovanR. FallicaA. Mokhles GeramiT. E. MølholtC. WiemerM. LongoH. P. GunnlaugssonK. JohnstonH. MasendaD. NaidooM. NcubeK. Bharuth-RamM. FanciulliH. P. GislasonG. LangoucheS. ÓlafssonG. WeyerNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 7, Iss 1, Pp 1-12 (2017)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q 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
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.
format	article
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
title	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_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_sort	atomic-scale study of the amorphous-to-crystalline phase transition mechanism in gete thin films
publisher	Nature Portfolio
publishDate	2017
url	https://doaj.org/article/8b8010c07dc04e4ba12f057b6f4b397d
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Atomic-scale study of the amorphous-to-crystalline phase transition mechanism in GeTe thin films

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