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

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


Titill: Atomic-scale study of the amorphous-to-crystalline phase transition mechanism in GeTe thin films
Höfundur: Mantovan, R.
Fallica, R.
Mokhles Gerami, A.
Mølholt, T. E.
Wiemer, C.
Longo, M.
Gunnlaugsson, Haraldur   orcid.org/0000-0002-8958-0245
Johnston, K.
Masenda, H.
Naidoo, D.
... 7 fleiri höfundar Sýna alla höfunda
Útgáfa: 2017-08-15
Tungumál: Enska
Umfang: 8234
Háskóli/Stofnun: Háskóli Íslands
University of Iceland
Svið: Verkfræði- og náttúruvísindasvið (HÍ)
School of Engineering and Natural Sciences (UI)
Deild: Raunvísindastofnun (HÍ)
Science Institute (UI)
Birtist í: Scientific Reports;7(1)
ISSN: 2045-2322
DOI: 10.1038/s41598-017-08275-5
Efnisorð: Information storage; Phase transitions and critical phenomena; Atómfræði; Eðlisfræði
URI: https://hdl.handle.net/20.500.11815/434

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Tilvitnun:

Mantovan, R., Fallica, R., Mokhles Gerami, A., Mølholt, T. E., Wiemer, C., Longo, M., . . . Weyer, G. (2017). Atomic-scale study of the amorphous-to-crystalline phase transition mechanism in GeTe thin films. Scientific Reports, 7(1), 8234. doi:10.1038/s41598-017-08275-5

Útdráttur:

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.

Leyfi:

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