Article Dans Une Revue Journal of Materials Chemistry C Année : 2021

Atypical phase-change alloy Ga 2 Te 3 : atomic structure, incipient nanotectonic nuclei, and multilevel writing

Andrey Tverjanovich
Maxim Khomenko
  • Fonction : Auteur
Chris Benmore
  • Fonction : Auteur
Sergei Bereznev
  • Fonction : Auteur
Anton Sokolov
Aleksei Kiselev
  • Fonction : Auteur
Andrey Lotin
  • Fonction : Auteur

Résumé

Emerging brain-inspired computing, including artificial optical synapses, photonic tensor cores, neuromorphic networks, etc., needs phase-change materials (PCMs) of the next generation with lower energy consumption and a wider temperature range for reliable long-term operation. Gallium tellurides with higher melting and crystallization temperatures appear to be promising candidates and enable achieving the necessary requirements. Using high energy X-ray diffraction and Raman spectroscopy supported by first-principles simulations, we show that vitreous g-Ga2Te3 films essentially have a tetrahedral local structure and sp3 hybridization, similar to those in the stable fcc Ga2Te3 polymorph and in contrast to a vast majority of typical PCMs. Nevertheless, optical pump–probe laser experiments revealed high-contrast, fast and reversible multilevel SET-RESET transitions raising a question related to the phase change mechanism. A recently observed nanotectonic compression in bulk glassy Ga–Te alloys seems to be responsible for the PCM performance. Incipient nanotectonic nuclei, reminiscent of monoclinic high-pressure HP-Te II and rhombohedral HP-Ga2Te3, are present as minorities (2–4%) in g-Ga2Te3 but are suggested to grow dramatically with increasing temperature while interacting with appropriate laser pulses. This leads to co-crystallization of HP-polymorphs amplified by a high internal local pressure reaching 4–8 GPa. The metallic HP-forms provide an increasing optical and electrical contrast, favorable for reliable PCM operations, and higher energy efficiency.
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Dates et versions

hal-04217950 , version 1 (18-10-2023)
hal-04217950 , version 2 (07-12-2023)

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Citer

Andrey Tverjanovich, Maxim Khomenko, Chris Benmore, Sergei Bereznev, Anton Sokolov, et al.. Atypical phase-change alloy Ga 2 Te 3 : atomic structure, incipient nanotectonic nuclei, and multilevel writing. Journal of Materials Chemistry C, 2021, 9 (47), pp.17019-17032. ⟨10.1039/D1TC03850H⟩. ⟨hal-04217950v2⟩
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