SnSe thin films of different thicknesses were prepared by the thermal
evaporation technique in vacuum of 10(-4) Pa. The structure analysis o
f the films as determined from the electron diffraction pattern and X-
ray diffraction indicate that the films were polycrystalline of orthor
hombic structure. The transmittance and reflectance of SnSe films were
measured at normal incidence in the wavelength range of 760-2200 nm.
It was found that the refractive index n and the absorption index k ar
e independent of the film thickness. Graphical representation of log(a
lpha) as a function of (1/lambda) shows two distinct linear parts indi
cating the existence of two optical transitions. The analysis of the s
pectral behavior of the absorption coefficient in the intrinsic absorp
tion region revealed an indirect and direct allowed transition E(g)(in
d) = 0.895 eV and E(g)(d) = 1.27, respectively.