Excitonic and other interband transitions in TlIn2 single crystals

Abstract

A study of the optical properties of the layered compound TlInS2 is presented. Reflection spectra were measured at room temperature, in the energy region 1.5-6.2 eV. Transmission spectra were measured in the temperature range 10-290K, in the energy region 1.5 to 3.5 eV. Two structures, at energy positions 2.57 and 2.87 eV (10K), are attributed to transitions to the ground exciton state, from valence states split because of the spin-orbit interaction, at the point G of the Brillouin zone. Lorentzian line shapes are used to fit the structures of excitonic origin. The temperature dependence of the peaks and their broadening parameters are also presented.