Some Optical properties for Ag x( Ga 0.4 Se 0.6 ) 100 - x system (x?=?2.5, 5.0, 7.5, 10.0 and 12.5)
Abstract
Thin films for Agx(Ga0.4 Se0.6)100-x (x=2.5, 5, 7.5, 10 and12.5 at. %) which prepared by thermal evaporation technique in room temperature,
The optical properties of Agx(Ga0.4Se0.6)100-x films as a function of Ag-content were studied by measurements (for spectrum range 400-1100 nm).
Transmittance, T and reflectance, R were measured . The extinction coefficient, k and the refractive index, n were found to be practically dependence on
the film composition, optical energy gap (Eg
opt), dispersion energy (Ed), oscillator energy (Eo) as well as, the high frequency dielectric constant () and the lattice dielectric constant (L). The optical gap, Egopt decreases (2.7: 2.4 eV) as the Ag-content increase (2.5:12.5at%), this decrease was attributed to the increase of the density of localized states according to Mott and Davis model. .