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Revealing the intrinsic nature of the mid-gap defects in amorphous Ge 2 Sb 2 Te 5

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Konstantinou, Konstantinos  ORCID logo
Lee, Tae-Hoon 
Elliott, Stephen R. 


Abstract: Understanding the relation between the time-dependent resistance drift in the amorphous state of phase-change materials and the localised states in the band gap of the glass is crucial for the development of memory devices with increased storage density. Here a machine-learned interatomic potential is utilised to generate an ensemble of glass models of the prototypical phase-change alloy, Ge2Sb2Te5, to obtain reliable statistics. Hybrid density-functional theory is used to identify and characterise the geometric and electronic structures of the mid-gap states. 5-coordinated Ge atoms are the local defective bonding environments mainly responsible for these electronic states. The structural motif for the localisation of the mid-gap states is a crystalline-like atomic environment within the amorphous network. An extra electron is trapped spontaneously by these mid-gap states, creating deep traps in the band gap. The results provide significant insights that can help to rationalise the design of multi-level-storage memory devices.



Article, /639/638/563/606, /639/638/563/979, /639/638/563/981, /639/301/119/995, /639/301/1005/1008, /119/118, /119, article

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Nature Communications

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Nature Publishing Group UK