Effect of In-content on the optical properties of a-Se films

The optical transmission spectra of amorphous (a-) Se1−xInx films, with x = 0.0, 0.05, 0.18 and 0.35, that prepared by thermal evaporation from their corresponding bulk ingots, are recorded over the spectral region of 500-2500 nm. A simple straight forward procedure proposed by Swanepeol has been applied to determine the two components of the complex refractive index (n˜). The dispersion of n˜ is examined in terms of the Wemple and DiDomenico model and is discussed in terms of In-content. An estimation of various optical parameters such as, the optical energy gap (Eg = 1.96-1.33 eV), single oscillator energy (Eo = 3.95-3.16 eV), oscillator dispersion energy (Ed = 22.6-31.6 eV), lattice oscillator strength (El = 0.38-0.61 eV) and wavelength at zero material dispersion (λc = 2.0569-2.0879 μm) have been given and discussed in relation to the coordination number, hydrostatic density and formed chemical bonds that are introduced in the network of a-Se with the introduction of up to 35 at.% In.