pISSN 0374-4914 eISSN 2289-0041

## Research Paper

New Physics: Sae Mulli 2006; 53: 232-239

Published online September 1, 2006

## The Optical Properties of Cd$_{1-x}$Mn$_x$S/GaAs(100) Epilayers Obtained by Using Spectroscopic Ellipsometry

D. J. KIM1*, T. G. KOO2, Y. D. CHOI3

1Institute of Science and Technology, Mokwon University, Daejeon 302-729
2Department of Physics, Chungnam National University, Daejeon 305-764
3Department of Optical & Electronic Physics, Mokwon University, Daejeon 302-729

Correspondence to:djkim@mokwon.ac.kr

### Abstract

Cd$_{1-x}$Mn$_x$S epilayers were grown on GaAs(100) substrates by using a hot-wall epitaxy method. The epilayers had mixed hexagonal and cubic structures, and their optical properties were investigated in the photon energy range between 2.0 - 6.5 eV at room temperature by using spectroscopic ellipsometry. The obtained data were analyzed for the critical points of the pseudodielectric function spectra, <$\varepsilon(E)$> = < $\varepsilon_1(E)$> + $i$ < $\varepsilon_2(E)$ >, such as the $E_0$, $E_1$, $E_1$ + $\Delta_1$, and $E_0^{\prime}$ structures. Also, the pseudodielectric function related optical constants of Cd1?xMnxS, such as the refractive index, the extinction coefficient, and the absorption coefficient, are presented and analyzed. Numerically calculated second-derivative spectra of the pseudodielectric functions < $\varepsilon(E)$ > of our Cd$_{1-x}$Mn$_x$S epilayers were deremined for a further analysis of the critical points. We could also observe peak shift of the respective critical points with increasing Mn composition.

Keywords: Cd$_{1-x}$Mn$_x$S, Spectroscopic ellipsometry, Hot-wall epitaxy, Dielectric function