Abstract
The optical properties of TlGaSeS at room temperature in the 0.96–5.05 eV photon-energy range has been investigated using variable angle spectroscopic ellipsometry (VASE). The obtained results of dielectric spectra data display different structures at critical points energies. The results are analyzed with reference to three models of the interband transitions in crystal semiconductors, namely, harmonic oscillator approximation (HOA), standard critical-point (SCP) model and critical-point parabolic-band (CPPB). Results are in plausible agreement with the both SCP and CPPB computations over the whole range of the photon wavelengths. Dielectric- correlated optical parameters of TlGaSeS, such as the absorption coefficient, the refractive index, and the orthogonal-incidence reflectivity are illustrated and investigated.