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Title: Structural transformations in Ge{sub 2}Sb{sub 2}Te{sub 5} under high pressure and temperature

The structural transformations occurring in Ge{sub 2}Sb{sub 2}Te{sub 5} films heated at temperature up to 400 °C, and under hydrostatic pressure up to 12 GPa, have been investigated through in-situ X ray diffraction measurements. The adopted experimental conditions are close to those experienced by the phase change material during the SET (crystallization)/RESET (amorphization) processes in a nonvolatile memory device. The compression enhances the thermal stability of the amorphous phase, which remains stable up to 180 °C at 8 GPa and to 230 °C at 12 GPa. The structure of the crystalline phases is also modified, with the formation of a CsCl-type structure instead of rock-salt and of a GeS-type structure at the temperature at which usually the trigonal stable phase is formed. Overall, the stability of the stable phase appears to be more affected by the compression. We argue that the presence of weak bonds associated to the van der Waals gaps is a determining factor for the observed reduced stability.
Authors:
; ; ;  [1] ;  [2] ;  [3] ; ;  [4] ;  [3] ;  [5] ;  [4] ;  [3]
  1. IMM-CNR, Istituto per la Microelettronica e Microsistemi, Consiglio Nazionale delle Ricerche, Strada VIII 5, Zona Industriale, I-95121 Catania (Italy)
  2. ICCOM-CNR, Istituto di Chimica dei Composti OrganoMetallici, Via Madonna del Piano 10, I-50019 Sesto Fiorentino (Italy)
  3. (Italy)
  4. LENS, European Laboratory for Non-Linear Spectroscopy, Via Nello Carrara 1, I-50019 Sesto Fiorentino (Italy)
  5. MATIS-IMM-CNR, via S. Sofia 64, I-95123 Catania (Italy)
Publication Date:
OSTI Identifier:
22494732
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 118; Journal Issue: 6; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; AMORPHOUS STATE; CESIUM CHLORIDES; CRYSTALLIZATION; GERMANIUM COMPOUNDS; GERMANIUM SULFIDES; MEMORY DEVICES; PHASE CHANGE MATERIALS; PRESSURE RANGE GIGA PA; STABILITY; TEMPERATURE RANGE 0400-1000 K; THIN FILMS; TRANSFORMATIONS; VAN DER WAALS FORCES; X-RAY DIFFRACTION