Optical properties of Bi₃₀Se_(70-x)Te_x amorphous thin films

The optical properties of vacuum deposited Bi₃₀Se_(70-x)Te_x amorphous thin films (where x = 35, 40 and 45 at%) with different thicknesses (150,200,250 nm) were studied in the wavelength range (400–900 nm). It was found that the optical absorption is due to indirect transition and the energy gap decreases with increasing Te content. The optical band gap Eg was found to be almost thicknesses independent. The optical constants n, k the real and imaginary parts of the dielectric constant have been also calculated.