Dielectric response of AlSb from 0.7 to 5.0 eV determined by in situ ellipsometry

We present pseudodielectric function data <ε>=<ε1>+i<ε2> from 0.7 to 5.0 eV of oxide-free AlSb that are the closest representation to date of the intrinsic bulk dielectric response ε of the material. Measurements were done on a 1.5 μm thick film grown on (001) GaAs by molecular beam epitaxy. Data were obtained with the film in situ to avoid oxidation artifacts. Overlapping critical-point (CP) structures in the E2 energy region were identified by means of band-structure calculations done with the linear augmented Slater-type orbital method. Calculated CP energies agree well with those obtained from data, confirming the validity of the calculations.