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Article Dans Une Revue Materialia Année : 2023

Quantification of fcc-Ge2Sb2Te5 stoichiometry variations

Résumé

Ge-rich Ge-Sb-Te (GGST) alloys are being currently integrated to the complementary metal oxide semiconductor technology for industrial production of new generation of non-volatile memories, able to support the development of raising technologies such as internet-of-things and artificial intelligence. These phase-change random access memories are based on ultra-fast reversible crystallization/amorphization of the Ge 2 Sb 2 T 5 (GST225) chalcogenide compound exhibiting a large resistivity contrast between the amorphous and crystalline states. GGST film crystallization is accompanied by the phase separation of Ge and an fcc-GST225 phase of unknown composition, which should vary with Ge excess of GGST films. However, device properties and reliability are expected to vary with fcc-GST225 stoichiometry. This work reports atom probe tomography, X-ray diffraction, and scanning transmission electron microscopy investigations of the crystallization of an amorphous GST225 layer containing pseudo-periodic local composition variations. The results show that the compound fcc-GST225 is not stoichiometric, accepting 10 Ge at% variations, 7.5 Sb at% variations, and 6 Te at% variations. Furthermore, the microstructure as well as element distributions in the crystallized fcc-GST225 film suggest that fcc-GST225 nucleation is piloted by local composition variations. Fcc-GST225 nuclei formed in the Te-richest regions of the amorphous layer, corresponding to bulk hetero-nucleation, lowering the nucleation temperature.
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Origine : Publication financée par une institution
Licence : CC BY NC ND - Paternité - Pas d'utilisation commerciale - Pas de modification

Dates et versions

hal-04275455 , version 1 (08-11-2023)

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Paternité - Pas d'utilisation commerciale - Pas de modification

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Guillaume Roland, Alain Portavoce, Maxime Bertoglio, Marion Descoins, Jacopo Remondina, et al.. Quantification of fcc-Ge2Sb2Te5 stoichiometry variations. Materialia, 2023, 32, ⟨10.1016/j.mtla.2023.101885⟩. ⟨hal-04275455⟩
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