Reversible Amorphous-to-Amorphous Transitions in Chalcogenide Films: Correlating Changes in Structure and Optical Properties

Authors

  • Maria Kalyva,

    1. Foundation for Research and Technology–Hellas, Institute of Chemical Engineering Sciences, (FORTH/ICE–HT), P.O. Box 1414, GR-26504 Patras, Greece
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  • Jiri Orava,

    1. Department of Materials Science and Metallurgy, University of Cambridge, Pembroke St., CB2 3QZ Cambridge, UK
    2. WPI-Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
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  • Angeliki Siokou,

    Corresponding author
    1. Foundation for Research and Technology–Hellas, Institute of Chemical Engineering Sciences, (FORTH/ICE–HT), P.O. Box 1414, GR-26504 Patras, Greece
    • Foundation for Research and Technology–Hellas, Institute of Chemical Engineering Sciences, (FORTH/ICE–HT), P.O. Box 1414, GR-26504 Patras, Greece.
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  • Martin Pavlista,

    1. Department of General and Inorganic Chemistry, Faculty of Chemical-Technology, University of Pardubice, Legion's sq. 565, 53210 Pardubice, Czech Republic
    2. Centre for Material Science, Studentska 95, 532 10 Pardubice, Czech Republic
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  • Tomas Wagner,

    1. Department of General and Inorganic Chemistry, Faculty of Chemical-Technology, University of Pardubice, Legion's sq. 565, 53210 Pardubice, Czech Republic
    2. Centre for Material Science, Studentska 95, 532 10 Pardubice, Czech Republic
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  • Spyros N. Yannopoulos

    Corresponding author
    1. Foundation for Research and Technology–Hellas, Institute of Chemical Engineering Sciences, (FORTH/ICE–HT), P.O. Box 1414, GR-26504 Patras, Greece
    • Foundation for Research and Technology–Hellas, Institute of Chemical Engineering Sciences, (FORTH/ICE–HT), P.O. Box 1414, GR-26504 Patras, Greece.
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Abstract

Structural transitions in materials are accompanied by appreciable and exploitable changes in physical-chemical properties. Whereas reversible optically-driven atomistic changes in crystal-to-amorphous transitions are generally known and exploited in applications, the nature of the corresponding polyamorphic transitions between two structurally distinct meta-stable amorphous phases is an unexplored theme. Direct experimental evidence is reported for the nature of the atomistic changes during fully reversible amorphous-to-amorphous switching between two individual states in the non-crystalline As50Se50 films prepared by pulsed-laser deposition and consequent changes in optical properties. Combination of surface sensitive X-ray photoelectron spectroscopy and spectroscopic ellipsometry show that the near-bandgap energy illumination and annealing induce reversible switching in the material's structure by local bonding rearrangements. This is accompanied by switching in refractive index between two well-defined states. Exploiting the pluralism of distinct structural states in a disordered solid can provide new insights into the data storage in emerging optical memory and photonic applications.

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