We present a study of the optical properties of cubic Zn 1-xMnxSe thin films with x=0,0.136 and 0.21, grown on GaAs(001) substrates by molecular beam epitaxy. We determine the complex dielectric function using variable-angle spectroscopic ellipsometry in the photon energy range from 0.75 to 4.5 eV. A critical-point parametric model including the two lowest critical points E0 and E0+Δ 0 is employed for the dielectric function. An excellent match of the experimental data is obtained in the below and near-band-gap photon energy range. For increasing Mn content we observe a large negative bowing of the band gap and an increase in the spin-orbit splitting (by 80% for 21% Mn). From the fit, an exciton binding energy of 17 meV is obtained for ZnSe. This value changes only slightly with the addition of Mn, namely to 17 and 20 meV for 13.6% and 21% Mn, respectively. The below-band-gap index of refraction is well represented by a simple Cauchy dispersion formula, which is provided here as well.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Jul 2004|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics