Optical properties of crystals of the solid solutions (InSb)1−x(CdTe)x

The reflection and absorption spectra of crystals of the solid solutions (InSb)1−x(CdTe)x in the wavelength interval 2.5–25 µm were measured within the limits of solubility of CdTe in InSb (x⩽0.05) at room temperature. Analysis of the experimental results confirmed the applicability of the Kane theory for all compositions investigated. The variation of the optical band gap ɛ g opt and the effective mass mc at the Fermi level as a function of composition was determined. It is shown that the minimum values mc=0.8×10−2m0 and ɛ g opt =0.07 eV are reached for x=0.02–0.03. Information about the predominant mechanism of scattering for each alloy is obtained from the absorption curves in the region of absorption by free charge carriers. X-Ray crystallographic investigations were performed and the change Δa(x) in the lattice constant of the solid solutions relative to pure InSb was determined. It is shown that the behavior of mc(x) and ɛ g opt is uniquely determined by Δa(x). In turn, Δa(x) is determined by the complicated character of the interaction of the dopants with one another and with the InSb lattice.