Optical properties of some glassy compositions of the GeSe2-xSnx thin films of the ternary chalcogenide system

Abstract EN

The optical transmission T(λ) spectra has been recorded, in the spectral range of 400-1100 nm, for thermally evaporated Sn doped GeSe2-xSnx films.

The X- ray diffraction technique was used to confirm the polymeric nature of the studied films.

The current optical theories and models were applied to analyze the recorded spectra and to calculate various interesting optical parameters.

These include: dispersion of the two components of both complex refractive index (n̂=n-ik) and complex dielectric constant (ε1 and ε2), energy gap (Eg), Urbach energy (Eu), single oscillator energy (Eo), lattice oscillating strength (Ed).

At this point, a similar non-monotonic trend is observed for the compositional dependence of various parameters.

This has been ascribed to the disorder and/or structural defects introduced due to the incorporation of Sn, up to 33.34 % Sn, in the GeSe2-xSnx structure.

It is observed that band gap decreases with the increase of Sn concentration in the system.

This variation in the band gap is explained on the basis of change in structure of the system due to the introduction of Sn in Ge-Se-Sn glassy system.