Ultrafast time-resolved electron diffraction revealing the nonthermal dynamics of near-UV photoexcitation-induced amorphization in Ge<inf>2</inf> Sb<inf>2</inf> Te <inf>5</inf>

Masaki Hada, Wataru Oba, Masashi Kuwahara, Ikufumi Katayama, Toshiharu Saiki, Jun Takeda, Kazutaka G. Nakamura

Research output: Contribution to journalArticle

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Abstract

Because of their robust switching capability, chalcogenide glass materials have been used for a wide range of applications, including optical storages devices. These phase transitions are achieved by laser irradiation via thermal processes. Recent studies have suggested the potential of nonthermal phase transitions in the chalcogenide glass material Ge<inf>2</inf> Sb<inf>2</inf> Te <inf>5</inf> triggered by ultrashort optical pulses; however, a detailed understanding of the amorphization and damage mechanisms governed by nonthermal processes is still lacking. Here we performed ultrafast time-resolved electron diffraction and single-shot optical pump-probe measurements followed by femtosecond near-ultraviolet pulse irradiation to study the structural dynamics of polycrystalline Ge<inf>2</inf>, Sb<inf>2</inf>, Te <inf>5</inf>. The experimental results present a nonthermal crystal-to-amorphous phase transition of Ge<inf>2</inf> Sb<inf>2</inf> Te,<inf>5</inf> initiated by the displacements of Ge atoms. Above the fluence threshold, we found that the permanent amorphization caused by multi-displacement effects is accompanied by a partial hexagonal crystallization.

Original languageEnglish
Article number13530
JournalScientific Reports
Volume5
DOIs
Publication statusPublished - 2015 Aug 28

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photoexcitation
electron diffraction
irradiation
dynamic structural analysis
glass
pulses
shot
fluence
crystallization
pumps
damage
thresholds
probes
crystals
lasers
atoms

ASJC Scopus subject areas

  • General

Cite this

Ultrafast time-resolved electron diffraction revealing the nonthermal dynamics of near-UV photoexcitation-induced amorphization in Ge<inf>2</inf> Sb<inf>2</inf> Te <inf>5</inf> / Hada, Masaki; Oba, Wataru; Kuwahara, Masashi; Katayama, Ikufumi; Saiki, Toshiharu; Takeda, Jun; Nakamura, Kazutaka G.

In: Scientific Reports, Vol. 5, 13530, 28.08.2015.

Research output: Contribution to journalArticle

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abstract = "Because of their robust switching capability, chalcogenide glass materials have been used for a wide range of applications, including optical storages devices. These phase transitions are achieved by laser irradiation via thermal processes. Recent studies have suggested the potential of nonthermal phase transitions in the chalcogenide glass material Ge2 Sb2 Te 5 triggered by ultrashort optical pulses; however, a detailed understanding of the amorphization and damage mechanisms governed by nonthermal processes is still lacking. Here we performed ultrafast time-resolved electron diffraction and single-shot optical pump-probe measurements followed by femtosecond near-ultraviolet pulse irradiation to study the structural dynamics of polycrystalline Ge2, Sb2, Te 5. The experimental results present a nonthermal crystal-to-amorphous phase transition of Ge2 Sb2 Te,5 initiated by the displacements of Ge atoms. Above the fluence threshold, we found that the permanent amorphization caused by multi-displacement effects is accompanied by a partial hexagonal crystallization.",
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AU - Hada, Masaki

AU - Oba, Wataru

AU - Kuwahara, Masashi

AU - Katayama, Ikufumi

AU - Saiki, Toshiharu

AU - Takeda, Jun

AU - Nakamura, Kazutaka G.

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