Optical properties of AsSeTl thin films deposited by e-beam evaporation

Five compositions of the system As25Se75-xTlx (x = 12, 16, 20, 24 and 28%) have been prepared using melt quenching technique. Thin films of the thickness (200 nm) were deposited by electron beam evaporation. Optical and other parameters of the films have been determined. The optical band gap E-op was found to decrease with increasing both of the coordination number r and the average number of bonds per atom N-av and with decreasing the heat of atomization H-s. The width of the band tails of the localized states in the band gap E-e increases with increasing thallium ratio. Other parameters such as the oscillator energy E-o, dispersion energy E-d and plasma frequency omega(p) have been determined.