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Title: Ultrafast crystalline-to-amorphous phase transition in Ge{sub 2}Sb{sub 2}Te{sub 5} chalcogenide alloy thin film using single-shot imaging spectroscopy

We have observed an irreversible ultrafast crystalline-to-amorphous phase transition in Ge{sub 2}Sb{sub 2}Te{sub 5} chalcogenide alloy thin film using broadband single-shot imaging spectroscopy. The absorbance change that accompanied the ultrafast amorphization was measured via single-shot detection even for laser fluences above the critical value, where a permanent amorphized mark was formed. The observed rise time to reach the amorphization was found to be ∼130–200 fs, which was in good agreement with the half period of the A{sub 1} phonon frequency in the octahedral GeTe{sub 6} structure. This result strongly suggests that the ultrafast amorphization can be attributed to the rearrangement of Ge atoms from an octahedral structure to a tetrahedral structure. Finally, based on the dependence of the absorbance change on the laser fluence, the stability of the photoinduced amorphous phase is discussed.
Authors:
; ; ;  [1] ;  [2]
  1. Department of Physics, Graduate School of Engineering, Yokohama National University, Yokohama 240-8501 (Japan)
  2. Graduate School of Science and Technology, Keio University, Yokohama 223-8522 (Japan)
Publication Date:
OSTI Identifier:
22304463
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 104; Journal Issue: 26; Other Information: (c) 2014 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; AMORPHOUS STATE; ANTIMONY COMPOUNDS; ATOMS; CHALCOGENIDES; CRYSTAL STRUCTURE; DETECTION; GERMANIUM COMPOUNDS; LASER RADIATION; PHONONS; PULSE RISE TIME; SPECTROSCOPY; STABILITY; TELLURIUM COMPOUNDS; TERNARY ALLOY SYSTEMS; THIN FILMS