Complex structure of optical transitions from the core $d$-levels of InAs and InSb crystals

Using an improved parameterless unified Argand diagram method, the permittivity spectra of InAs and InSb crystals in the range of 15–40 eV are decomposed into thirteen and twelve separate components, respectively, with the three main parameters, specifically, the maximum energies, half-width, and oscillator strength determined for each of them. The oscillator strengths are in the ranges of 0.006–0.10 for InAs and 0.014–0.076 for InSb. The permittivity spectra were preliminary calculated on the basis of experimental reflectance and absorption spectra using Kramers–Kronig integral relations. On the basis of a model of interband and exciton transitions, the nature of the obtained transition bands is suggested.