Structure and optical properties in the amorphous to crystalline transition in AgSbSe2 thin films

Nearly stoichiometric thin films of the ternary AgSbSe2 compound have been deposited at room temperature by conventional thermal evaporation of the presynthesized material onto glass substrate. The X-ray and electron diffraction studies revealed that the as-deposited films are amorphous in nature, while an amorphous-to-crystalline phase transition could be obtained by thermal annealing at 373 K. The elemental chemical composition of as-deposited films was confirmed using the energy dispersive X-ray analysis. The transmission and reflection spectra of as-deposited and annealed films at annealing different temperatures were recorded at normal light incidence in the wavelength range 600-2500 nm. The refractive index and optical band gap have been calculated for the investigated films. The dispersion parameters, (Eo, Ed) static refractive index ns (0), static dielectric constant, ϵs and the carrier concentration to the effective mass ratio, N/m* have been calculated. An analysis of the optical absorption spectra revealed a non direct optical transition characterizing the as-deposited films and those annealed at 343 and 374 K while; direct and indirect optical transitions characterized the films annealed at 398 K. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)