Optical Absorption of Chalcogenide Glass Ga₂S₃-La₂S₃ Doped with Erbium

Abstract

The glasses of the La2S3-Er2S3-Ga2S3 system were synthesized from the melted samples which where quenched in to the cold 25% solution of NaCl. Their optical absorption spectra were studied in the range of 1.2–2.9 eV at 80 K. For doped erbium glasses, there are narrow absorption bands with maxima at 2.53, 2.35, 2.27, 1.88, 1.54, 1.26 eV. With increasing of the content of La2S3 (30 - 40 mol. %) the bandgap width decreases (Eg = 2.83 - 2.73 eV) and the Urbach parameter increases (E = 151 - 238 meV). These changes are determined by the structural disorder in the glasses. Keywords: glassy alloys, optical absorption, Urbach's rule.