Determination of the thickness and spectral dependence of the refractive index of Al x In1-x Sb epitaxial layers from reflectance spectra

A nondestructive method for measuring the thicknesses of epitaxial layers of Al (x) In1 - x Sb alloys based on interference effects in reflectance spectra measured in a wide wavelength range (1-28 mu m) is implemented. The studied 0.9-3.3 mu m thick Al (x) In1 - x Sb layers are grown on highly lattice-mismatched GaAs substrates by molecular beam epitaxy. The found thicknesses are in good agreement with the independent data of scanning electron microscopy. The spectral dependence of the refractive index n(E) of Al (x) In1 - x Sb layers is measured both for the regions of transparency and fundamental absorption. The refractive index for the case of E < E (0) was calculated by a double-oscillator model using a refined experimental dependence of the band gap on the composition E (0)(x). The experimental data on the n(E) of Al (x) In1 - x Sb for energies E > E (0) are found based on the interference pattern.