High-lying interband transitions and optical properties of In As1-x Sbx films

In As1-x Sbx has been grown by liquid phase epitaxy on (100) InAs substrate with x up to 0.11, and optical properties of the material have been investigated using spectroscopic ellipsometry at room temperature within 1.5-5.5 eV. The dielectric function ε (E) spectra that show well-defined structures associated with E1, E1 + Δ1, and E2 transitions have been observed and analyzed by a model dielectric function based on interband transition theory. Excellent agreement between the model calculation and the experimental data is achieved over the entire energy range studied. The transition energies E1 and E2, the spin-orbit splitting energy Δ1, and the broadening parameters as functions of Sb concentration are fit linearly.