Ellipsometric and thermoreflectance spectra of (AlxGa1−x)0.5In0.5P alloys

Spectroscopic-ellipsometry (SE) and thermoreflectance (TR) spectra of (AlxGa1−x)0.5In0.5P quaternary alloys are presented. Both measurements are carried out on the same samples in the 1–6 eV photon-energy range at room temperature. These spectra are analyzed based on a simple model of the interband transitions. The results are in satisfactory agreement with the experimental SE and TR data over the entire range of photon energies. The composition dependence of the interband critical-point and indirect-band-gap energies is also discussed.