Determination of the optical constants of amorphous AsxS100−x films using effective-medium approximation and OJL model

摘要: Abstract The transmission spectra were used to obtain an efficient parameterization of the spectral dependences optical constants amorphous As–S thin films by applying a suitable dielectric function model. For studying compositional dependence constants, different compositions As x S 100− (  = 10, 15, 20, 25, 30 and 40 at%) deposited thermal evaporation technique in base pressure 7.5 × 10 −6  Torr at room temperature. (measured wavelength range 0.2–0.9 μm) analyzed O’Leary, Johnson, Lim (OJL) model based on joint density states (JDOS) functions. However, best fit data was obtained considering two-layer configuration film; top layer assumed be consisted bulk AsS material embedded voids (air). Therefore, OJL along with Bruggeman effective-medium approximation (BEMA) determine effective films. photon energy function, ɛ  =  r  −  iɛ i investigated presented. film thickness, absorption coefficient α , refractive index n extinction k static (0) band gap E g have been deduced. It found that increase arsenic content up stoichiometric 40 60 indirect decreases, while increases.