Ultrafast crystalline-to-amorphous phase transition in Ge 2Sb2Te5 chalcogenide alloy thin film using single-shot imaging spectroscopy

Jun Takeda, Wataru Oba, Yasuo Minami, Toshiharu Saiki, Ikufumi Katayama

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Abstract

We have observed an irreversible ultrafast crystalline-to-amorphous phase transition in Ge2Sb2Te5 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 A1 phonon frequency in the octahedral GeTe6 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.

Original languageEnglish
Article number261903
JournalApplied Physics Letters
Volume104
Issue number26
DOIs
Publication statusPublished - 2014

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ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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