Optical constants of InSe and In4Se3 thin films in the far infrared region

By using the flash evaporation technique we have obtained InSe and In4Se3 thin films, their reflectance measurements are recorded at ambient temperatures, in the far infrared range (50-400 cm(-1)) and for E polarisation. The theoretical curves of reflectivity show that optical properties are strongly dependent on the thickness of thin films. In order to determine the optical constants (i.e. the real and imaginary parts of respectively the refractive index and the dielectric function). Finally electrical parameters such as free carrier concentration and their scattering times and vibrational frequencies of phonons are determined by the fit of the reflectivity spectrum. (C) 2000 Elsevier Science B.V. All rights reserved.