Chalcogenide Se75Sb10In15
thin films of different
thickness (50–300 nm) are deposited using thermal
evaporation technique. The thermogram of the chalcogenide
bulk Se75Sb10In15
is obtained using a differential scanning
calorimetry (DSC). The crystallization temperature
Tc, peak crystallization temperature Tp and melting temperature
Tm, are identified. The X-ray diffraction (XRD) examination
indicates the crystallinity of the as-deposited film
decreases with increasing of thickness. Optical transmission
and reflection spectra are recorded in the wavelength
range of the incident photons from 250 to 2500 nm. It is
found that the film thickness affects the absorption coefficient,
refractive index, extinction coefficient and the width
of the tails of localized states in the gap region. The absorption
mechanism of the as-deposited films is a direct allowed
transition. The optical band gap energy (Eg) decreases from
3.31 to 2.51 eV with increasing the film thickness from 50
to 300 nm. The behavior of Eg is explained on the basis of
the structure disorders in the thicker films. The effect of the
film thickness on the single-oscillator and dispersion energies
is studied by the dispersion analyses of the refractive
index.