Ellipsometric studies of the dielectric function of Cd1-xMnxTe alloys.

Abstract

We present ellipsometric measurements of the dielectric function of a series of ${\mathrm{Cd}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{Mn}}_{\mathrm{x}}$Te samples (0lxl0.7) in the (1.5--5.5)-eV photon-energy region at room temperature. The data display structures which can be attributed to the ${E}_{0}$, ${E}_{0}$+${\ensuremath{\Delta}}_{0}$, ${E}_{1}$, ${E}_{1}$+${\ensuremath{\Delta}}_{1}$, and ${E}_{2}$ critical points of zinc-blende-type semiconductors: A fit of these structures with standard analytic expressions yields the energies, widths, strengths, and excitonic phase angles of the critical points. While the energy of the ${E}_{0}$ critical points increases with x, those of ${E}_{1}$ and ${E}_{1}$+${\ensuremath{\Delta}}_{1}$ decrease slightly. This fact is probably related to an increasing admixture of spin-up Mn 3d states into the initial valence states of these transitions.