Ellipsometric study of the optical properties of TlInSeS layered crystal

Abstract TlInSeS optical properties at photon energy ranges from 0.96 to 5.06 eV have been determined by means of variable-angle spectroscopic ellipsometry (VASE). This energy range contains the fundamental band gap. The measured pseudo-dielectric e(E) spectrum depicts different peaks. The spectrum is analyzed with reference of two inter-band transitions models that postulated for crystal semiconductors, explicitly, critical point parabolic band (CPPB) and standard critical-point (SCP) models. It is noted that both dielectric function models illustrates the plausible agreement with the experiment e(E) spectra. The optical properties of the present sample as extension coefficient refractive index absorption coefficient and the normal-reflectance, are investigated. The elemental composition of TlInSeS system has been confirmed by means of Energy Dispersive X-ray fluorescence spectrometer (EDXRF).