Effect of In incorporation on optical properties of amorphous Se–Ge thin films

Measurements of optical properties have been made on alloyed samples of Se and Ge with In prepared under vacuum by quenching the melt into water. The optical transmission spectra of film Se90Ge10−xInx (x=2, 4 and 6) were measured in the wavelength range 400–2000 nm by spectrophotometer. It is observed from optical transmission measurements that optical energy gap (Eg) decreases with In content. It is also found that refractive index (n), real dielectric constant (ε′) decreases with wavelength (λ) while extinction coefficient (k  ), imaginary dielectric constant (ε″ε″) increases with wavelength (λ). The absorption coefficient (α) increases with photon energy (hν).