Temperature dependent dielectric functions of molecular beam epitaxy-grown Ga1–xMnxAs thin films

Spectroscopic ellipsometry was used to measure the dielectric functions of a series of Ga1–xMnxAs samples from 10 K to 300 K. Initially, by modeling the ellipsometric data in the transparent region, the film thickness and the index of refraction of Ga1–xMnxAs alloys were obtained. Extending the analysis into the absorption region, the dielectric function for the entire spectral range between 0.6 eV and 6.5 eV was determined. Monitoring the temperature dependence of two critical points, corresponding to two electronic transitions in the Brillouin zone, we deduced the electron–phonon coupling parameters using Bose–Einstein occupation distributions. In comparison to GaAs, we find that the ternary alloy Ga1–xMnxAs shows a slight enhancement in its electron–phonon coupling.