Effect of Composition on the Optical and Electrical Conductivity of CuIn(SexS1‑x)2

Optical and electrical conductivity of chalcopyrite CuIn(Se_xS_1‑x)₂ (0 ≤ x ≤ 1) amorphous thin films are investigated. A transmission has been measured in a wavelength range (200 ≤ λ ≤ 2500 nm). The calculated optical energy band gap (E_g) and Urbach tail (band tail width) E_u decrease with increasing Se content. Refractive index (n) is estimated according to the Wemple–DiDomenico single oscillator model. Oscillator energy (E_°), dispersion energy (E_d), and the ratio of free carrier concentration to electron effective mass (N/m^*) are calculated from optical data for all thin films. Also, the high frequency dielectric constant at an infinite wavelength (ɛ_∞), lattice high frequency dielectric constant (ɛ_L) and static refractive index (n_°) are determined. Electrical conductivity (σ) is obtained at room temperature.