Optical properties of Se–Te–Sb thin films

Abstract

Amorphous thin films of Se80Te(20–X)SbX (X = 0, 4, 8, and 10 at. %) were deposited onto clean quartz substrates by vapour deposition (thermal evaporation) under a vacuum of 10−5 Torr. The transmission spectra at normal incidence in the spectral range of 250–2500 nm were measured at room temperature. The optical energy gap Eg was found to be indirect. The value of Eg was found to decrease from 1.69 to 1.43 eV with increasing Sb content. The composition dependence of the optical energy gap is discussed in terms of the chemical bond approach. The band tail width of localized states Ee was found to increase from 0.0297 to 0.0551 eV with increasing Sb content.