Octahedral to tetrahedral bonding transitions in the local structure of phase change optical media Ge2Sb2Se5 x Te5−5 x with Se doping

Random access memories utilize fast, reversible switching between ordered and disordered states of matter in phase change materials (PCMs) such as Ge2Sb2Te5−5x. The short-range structure in the disordered phase has been described either as (i) a network of Ge tetrahedra or (ii) Peierls distorted Ge/...

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Bibliographic Details
Published in:AIP advances 2023-04, Vol.13 (4)
Main Authors: Xu, Zhenyang, Restrepo, Francisco, Zhao, Junjing, Chatterjee, Utpal, Louca, Despina
Format: Article
Language:English
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Summary:Random access memories utilize fast, reversible switching between ordered and disordered states of matter in phase change materials (PCMs) such as Ge2Sb2Te5−5x. The short-range structure in the disordered phase has been described either as (i) a network of Ge tetrahedra or (ii) Peierls distorted Ge/Sb octahedra. The PCM transition was investigated in bulk Ge2Sb2Se5xTe5−5x (GSST), in which amorphization sets in with Se doping (x ≈ 0.85) upon quenching. GSST has a hexagonal crystalline ground state with Ge/Sb octahedral coordination, but the phase change transition to the amorphous state that is only observed when the system is quenched brings a short-range structure with sharp, tetrahedrally coordinated Ge/Sb correlations and shortened bonds that are distinctly different from the expected octahedral pairing.
ISSN:2158-3226
2158-3226
DOI:10.1063/5.0133981