OPTICAL PROPERTIES OF PHASE-CHANGE CHALCOGENIDES IN THE IR RANGE

Authors

DOI:

https://doi.org/10.20535/kpi-sn.2020.1.198013

Keywords:

Chalcogenides, Optical spectroscopy, Dielectric function, Disorder, Crystal lattice

Abstract

Background. The work is devoted to the study of the optical properties of chalcogenide compounds (GeTe)x(Sb2Te3)1-x, which are promising for use as functional materials in non-volatile memory devices and displays. Information storage is based on the contrast of physical properties between the crystalline and amorphous states of these compounds, which in a metastable crystalline state form a distorted cubic lattice with a high concentration of vacancies.

Objective. The aim of the paper is to study the influence of structural and thermally induced disorder on the contribution of free charge carriers to the dielectric function of (GeTe)x(Sb2Te3)1-x chalcogenides and on the optical properties of these materials in the vicinity of the main edge of optical absorption.

Methods. The results were obtained by analysis of IR reflectance spectra of the (GeTe)x(Sb2Te3)1-x  samples.

Results. It was determined that the width of localized electronic states, the Tauc parameter, and the contribution of plasmons to the dielectric function of phase change chalcogenides (GeTe)x(Sb2Te3)1-x depend on the concentration of vacancies and their ordering. The data obtained confirm that a change in the concentration of vacancies and their ordering in samples of (GeTe)x(Sb2Te3)1-x chalcogenides leads to change of the type of their electroconductivity.

Conclusions. The width of the localized electronic states and Tauc parameter depend on the concentration of vacancies and their ordering. A decrease in the concentration of vacancies leads to an increase in the contribution of free charge carriers to the dielectric function of (GeTe)x(Sb2Te3)1-x; their ordering entails large changes in the values of the plasmon frequency and their damping coefficient. The results provide information on ways of (GeTe)x(Sb2Te3)1-x properties’ modification.

Author Biographies

Kostiantyn V. Shportko, V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine

Костянтин Валентинович Шпортько

Evgen F. Venger, V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine

Євген Федорович Венгер

References

S.R. Ovshinsky, “Reversible electrical switching phenomena in disordered structures”, Phys. Rev. Lett., vol. 21, p. 1450, 1968. doi: 10.1103/PhysRevLett.21.1450

P. Hosseini et al., “An optoelectronic framework enabled by low-dimensional phase-change films”, Nature, vol. 511, p. 206, 2014. doi: 10.1038/nature13487

P. Guo et al., “A review of germanium-antimony-telluride phase change materials for non-volatile memories and optical modulators”, Appl. Sci., vol. 9, no. 3, p. 530, 2019. doi: 10.3390/app9030530

A.V. Kolobov and J. Tominaga, Chalcogenides, vol. 164. Berlin, Heidelberg, Germany: Springer, 2012.

K.D. Bogoslovsky and N.A. Tsendin, “Physics of switching and memory effects in chalcogenide glassy semiconductors”, Fizika i Tekhnika Poluprovodnikov, vol. 46, no. 5, pp. 577–608, 2012.

K. Shportko et al., “Anharmonicity of the vibrational modes of phase-change materials: A far-infrared, terahertz, and Raman study”, Vib. Spectrosc., vol. 95, pp. 51–56, 2018. doi: 10.1016/j.vibspec.2018.01.005

P.W. Anderson, “Absence of diffusion in certain random lattices”, Phys. Rev., vol. 109, no. 5, pp. 1492–1505, 1958. doi: 10.1103/PhysRev.109.1492

Downloads

Published

2020-03-06

Issue

No. 1 (2020)

Section

Статті

License

Copyright (c) 2020 The Author(s)

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

The ownership of copyright remains with the Authors.
 
Authors may use their own material in other publications provided that the Journal is acknowledged as the original place of publication and National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute” as the Publisher.

Authors who publish with this journal agree to the following terms:

  1. Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under CC BY 4.0 that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.

  2. Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.

  3. Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work