Origin of radiation tolerance in amorphous Ge ₂ Sb ₂ Te ₅ phase-change random-access memory material

Abstract

The radiation hardness of amorphous GeSbTe phase-change random-access memory material has been elucidated by ab initio molecular-dynamics simulations. Ionizing radiation events have been modeled to investigate their effect on the atomic and electronic structure of the glass. Investigation of the short- and medium-range order highlights a structural recovery of the amorphous network after exposure to the high-energy events modeled in this study. Analysis of the modeled glasses reveals specific structural rearrangements in the local atomic geometry of the glass, as well as an increase in the formation of large shortest-path rings. The electronic structure of the modeled system is not significantly affected by the ionizing radiation events, since negligible differences have been observed before and after irradiation. These results provide a detailed insight into the atomistic structure of amorphous GeSbTe after irradiation and demonstrate the radiation hardness of the glass matrix.

Revealing the intrinsic nature of the mid-gap defects in amorphous Ge2Sb2Te5

“…The atomic geometry of each glass model was optimised, and the electronic structure was calculated by using the non-local PBE0 functional, with a cutoff radius of 3 Å for the truncated Coulomb operator 64 . The inclusion of the Hartree–Fock exchange provides an accurate description of the band gap and the localised defect states in our 225GST glass models, as was demonstrated in our previous work 65 . The computational cost of hybrid-functional calculations can be reduced by using the auxiliary density-matrix method 66 (see Supplementary Note 11 for details), as employed in previous modelling studies of amorphous materials 67,68 .…”

Recent Advances on Neuromorphic Devices Based on Chalcogenide Phase‐Change Materials

“…[ 41,42 ] Meanwhile, electronic memory devices made from PCMs show excellent performance such as fast switching, high stability, low programming energy, and good endurance. [ 43–46 ] The commercialized products of the PCM memory (i.e., 3D‐XPoint [ 47 ] ) demonstrate its ability to be compatible with the existing semiconductor processing lines, so that the large‐scale integration of complicated neuromorphic systems becomes possible.…”

Reversible and irreversible resistance changes for gamma-ray irradiation in silver-diffused germanium telluride

“…The radiation hardness arises from the structural recovery of the amorphous network after exposure, as well as the memory operation mechanism based on the phase change rather than the electric charge as in floating gate memories. The structural recovery and the specific structural rearrangements in the local atomic geometry were demonstrated by ab initio molecular-dynamics simulations on Ge 2 Sb 2 Te 5 [4]. The radiation hardness and the structural recovery have also been studied intensively in Ag-doped Ge-chalcogenides.…”