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Title: Anharmonicity of the vibrational modes of phase-change materials: A far-infrared, terahertz, and Raman study

Abstract

Phase-change materials are employed as active elements in optical and electronic memory devices. Upon crystallization, their visible and near-infrared dielectric properties change dramatically due to the formation of resonant bonds, a unique type of bond related to both metallic and covalent bonds. In this work we study the change of the anharmonicity upon crystallization as well as the impact of vacancy concentration and vacancy ordering on the anharmonicity. Our temperature-dependent study of vibrational modes directly reveals a correlation between anharmonicity, vacancy concentration, and ordering. Previously, such a correlation was derived only indirectly from measurements of the specific heat. Furthermore, the pronounced far-infrared contrast, even larger than the optical one, can enable the application of phase-change materials in photonic devices.

Authors:
 [1];  [2];  [3];  [4];  [4]
  1. National Academy of Sciences of Ukraine, Kyiv (Ukraine); RWTH Aachen Univ., Aachen (Germany)
  2. SLAC National Accelerator Lab., Menlo Park, CA (United States); European XFEL GmbH, Schenefeld (Germany)
  3. SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States)
  4. Univ. of Cologne, Cologne (Germany)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1461623
Grant/Contract Number:  
AC02-76SF00515
Resource Type:
Accepted Manuscript
Journal Name:
Vibrational Spectroscopy
Additional Journal Information:
Journal Volume: 95; Journal Issue: C; Journal ID: ISSN 0924-2031
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Phonons; Anharmonicity; IR; Raman; THz; Phase-change materials

Citation Formats

Shportko, Konstantin, Zalden, P., Lindenberg, A. M., Ruckamp, R., and Gruninger, M. Anharmonicity of the vibrational modes of phase-change materials: A far-infrared, terahertz, and Raman study. United States: N. p., 2018. Web. doi:10.1016/j.vibspec.2018.01.005.
Shportko, Konstantin, Zalden, P., Lindenberg, A. M., Ruckamp, R., & Gruninger, M. Anharmonicity of the vibrational modes of phase-change materials: A far-infrared, terahertz, and Raman study. United States. doi:10.1016/j.vibspec.2018.01.005.
Shportko, Konstantin, Zalden, P., Lindenberg, A. M., Ruckamp, R., and Gruninger, M. Wed . "Anharmonicity of the vibrational modes of phase-change materials: A far-infrared, terahertz, and Raman study". United States. doi:10.1016/j.vibspec.2018.01.005. https://www.osti.gov/servlets/purl/1461623.
@article{osti_1461623,
title = {Anharmonicity of the vibrational modes of phase-change materials: A far-infrared, terahertz, and Raman study},
author = {Shportko, Konstantin and Zalden, P. and Lindenberg, A. M. and Ruckamp, R. and Gruninger, M.},
abstractNote = {Phase-change materials are employed as active elements in optical and electronic memory devices. Upon crystallization, their visible and near-infrared dielectric properties change dramatically due to the formation of resonant bonds, a unique type of bond related to both metallic and covalent bonds. In this work we study the change of the anharmonicity upon crystallization as well as the impact of vacancy concentration and vacancy ordering on the anharmonicity. Our temperature-dependent study of vibrational modes directly reveals a correlation between anharmonicity, vacancy concentration, and ordering. Previously, such a correlation was derived only indirectly from measurements of the specific heat. Furthermore, the pronounced far-infrared contrast, even larger than the optical one, can enable the application of phase-change materials in photonic devices.},
doi = {10.1016/j.vibspec.2018.01.005},
journal = {Vibrational Spectroscopy},
number = C,
volume = 95,
place = {United States},
year = {2018},
month = {1}
}

Journal Article:
Free Publicly Available Full Text
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Cited by: 1 work
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Figures / Tables:

Fig. 1 Fig. 1: Optical conductivity σ1 of studied materials. The vertical dashed lines at 50 cm-1 indicate the lower limit of our FTIR measurements. I. AgInTe2 in the amorphous (blue) and crystalline (red) states. II–IV. The change of σ1 between amorphous and crystalline states is much more pronounced in GST (samemore » color code as in section I). The crystalline state of GST is obtained after annealing at 160 °C. For comparison, THz-TDS spectroscopy data are shown for GeSb2Te4 in the as-deposited amorphous state and in the crystalline configuration after annealing at 170 °C. The difference between THz data and IR data for crystalline GeSb2Te4 can be attributed to the different annealing conditions.« less

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Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.