Absorption Edge and Optical Band Gap of $Ag-As_{40}S_{30}Se_{30}$ Amorphous Samples

The paper describes the results of a study of the influence of silver content on the absorption edge and optical band gap of the newly synthesized glasses of the $Ag_{x}(As_{40}S_{30}Se_{30})_{100-x}$ type for x=0, 0.5, 1, 2, 3, 5 at.% and of the corresponding films. The synthesis of bulk samples was performed in a rocking furnace from high-purity elemental components by a melt quenching method. Films were prepared from the synthesized bulk samples by pulsed laser deposition. Transmission spectra of the investigated samples were recorded at room temperature. The absorption edge and the optical band gap were determined by extrapolating the linear parts of the absorption spectra. It was found that the investigated range of Ag doping concentrations has a great influence on the absorption edge and optical band gap. Namely, with the increase of the silver content in the material the optical band gap showed a decrease. For films, it decreased from 2.02 eV, for the glass without silver, to 1.805 eV for the composition with 5 at.% Ag, whereas for the analogous bulk samples this decrease was from 1.84 eV to 1.609 eV.