Atomic Structure and Dynamics of Unusual and Wide‐Gap Phase‐Change Chalcogenides: A GeTe2 Case

Brain‐inspired computing, reconfigurable optical metamaterials, photonic tensor cores, and many other advanced applications require next‐generation phase‐change materials (PCMs) with better energy efficiency and a wider thermal and spectral range for reliable operations. Germanium ditelluride (GeTe2...

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Bibliographic Details
Published in:Physica status solidi. PSS-RRL. Rapid research letters 2024-10, Vol.18 (10), p.n/a
Main Authors: Usuki, Takeshi, Benmore, Chris J., Tverjanovich, Andrey, Bereznev, Sergei, Khomenko, Maxim, Sokolov, Anton, Fontanari, Daniele, Ohara, Koji, Bokova, Maria, Kassem, Mohammad, Bychkov, Eugene
Format: Article
Language:English
Subjects:
Atomic structure
atomic structures
Crystallization
Disproportionation
Energy gap
First principles
Germanium
High temperature
Internal pressure
Metamaterials
phase‐change materials
Photonic crystals
Pulsed laser deposition
Pulsed lasers
semiconductor–metal transition | viscosities
Tensors
Thermal stability
Two dimensional materials
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Summary:Brain‐inspired computing, reconfigurable optical metamaterials, photonic tensor cores, and many other advanced applications require next‐generation phase‐change materials (PCMs) with better energy efficiency and a wider thermal and spectral range for reliable operations. Germanium ditelluride (GeTe2), with higher thermal stability and a larger bandgap compared to current benchmark PCMs, appears promising for THz metasurfaces and the controlled crystallization of atomically thin 2D materials. Using high‐energy X‐Ray diffraction supported by first‐principles simulation, the atomic structure in semiconducting pulsed laser deposition films and metallic high‐temperature liquids is investigated. The results suggest that the structural and chemical metastability of GeTe2, leading to disproportionation into GeTe and Te, is related to high internal pressure during a semiconductor–metal transition, presumably occurring in the supercooled melt. Similar phenomena are expected for canonical GeS2 and GeSe2 under high temperatures and pressures. Unconventional phase‐change telluride GeTe2 is promising for THz metasurfaces and the controlled crystallization of 2D materials. Its chemical metastability, represented by GeTe2 ⇌ GeTe + Te, seems to be related to high internal pressure in the metallic melt compared to a less dense semiconducting glass film, exhibiting contrasting structural and electronic properties.
ISSN:1862-6254
1862-6270
DOI:10.1002/pssr.202300482