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Spectroscopic Characteristics of Zn$_{1-x}$Mn$_{x}$S Thin Films by Ellipsometry and Absorptance Measurements
New Phys.: Sae Mulli 2020; 70: 524~530
Published online June 30, 2020;
© 2020 New Physics: Sae Mulli.

Dae Jung KIM1, Bong Jin KIM1, Duk Hyeon KIM1, Jong Won LEE2*

1School of Basic Sciences, Hanbat University, Daejeon 34158, Korea
2Department of Advanced Materials Engineering, Hanbat University, Daejeon 34158, Korea
Correspondence to:
Received March 16, 2020; Revised April 6, 2020; Accepted May 11, 2020.
cc This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Zn$_{1-x}$Mn$_{x}$S thin films were grown on GaAs(100) substrates by using hot-wall epitaxy. X-ray diffraction patterns revealed the crystal structure of the epilayer. The optical properties were investigated using spectroscopic ellipsometry at 300 K from 3.0 -- 8.7 eV. The obtained data were analyzed to determine the critical points of the pseudodielectric function spectra, $\langle\varepsilon(E)\rangle=\langle\varepsilon_{1}(E)\rangle+\langle\varepsilon_{2}(E)\rangle$, such as $E_{0}/E_{0}+\Delta_{0}$, $E_{1}$, and three $E_{2}(\Sigma,\Delta,\Gamma)$structures. These critical points were determined by fitting analytical line-shapes to numerically calculated derivatives of the pseudodielectric functions. In particular, the transmittance/absorptance measurements were carried out to obtain the optical properties of the Zn$_{1-x}$Mn$_{x}$S epilayers, and the exact optical energy bandgap ($E_{g}$) was determined by comparing these results with the results of the ellipsometry measurements. Also, the energy band structures from the ellipsometry and the absorptance measurements were analyzed as a function of Mn concentration. The results obtained demonstrate that ellipsometry can be efficiently and non-destructively used to examine the energy bandgap of Zn$_{1-x}$Mn$_{x}$S epilayers.
PACS numbers: 73.20.A, 78.20.C
Keywords: Zn$_{1-x}$Mn$_{x}$S thin film, Spectroscopic ellipsometry, Hot-wall epitaxy, X-ray diffraction patterns, Pseudo dielectric functions, Critical points, Transmission measurement

June 2020, 70 (6)
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