Optical properties of Zn1-xMnxSe (x ≤ 0.78) epilayers

The optical properties of Zn1-xMnxSe with x up to 0.78 grown by molecular beam epitaxy on GaAs (001) substrates are reported. The complex dielectric functions epsilon = epsilon (1) + i epsilon (2) are obtained by spectroscopic ellipsometry in the photon range from 3.5 to 5.5 eV at room temperature. The critical-point energies E-1 and E-1 + Delta (1) for x less than or equal to 0.52 are determined by fitting the calculated second-derivative spectra of e to the standard line shape. For the sample with x = 0.78, the peak position in the E, spectrum is taken as an estimate for E-1. While the fundamental band gap E-0 increases with x, the E-1 and E-1 + Delta (1) energies decrease almost linearly with x. Comparing our results with those of the other experimental and theoretical studies, we consider the sp-d hybridization between the Mn 3d level and the sp band states to be an important factor affecting the band structures at the L point in the Brillouin zone over the whole range of Mn concentration. (C) 2001 Published by Elsevier Science Ltd.