Physical and optical properties of a-Ge-Sb-Se-Te bulk and film samples: Refractive index and its association with electronic polarizability of thermally evaporated a-Ge15-xSbxSe50Te35 thin-films

This work is dedicated to the deduction of many basic physical parameters of a-Ge15-xSbxSe50Te35 bulk and thin-film samples, GSST (0.0 <= x <= 15.0 at.wt.%). Besides, study the interrelationships among refractive index, molar refractivity and electronic polarizability of these film samples. Solid-state solutions of GSST compositions were prepared followed by melt-quenching method to get the glassy bulk samples. The thin-film samples of thickness 200 nm were fabricated by thermal evaporation technique. X-ray diffractograms revealed that all prepared GSST bulk and film samples are of non-crystalline nature. The ingots bulk Ge-Sb-Se-Te samples have been used to practically estimate the density. The refractive index of a-Ge15-xSbxSe50Te35 amorphous thin-films have been utilized to discuss the electronic polarizability, Covalence parameter and optical electronegativity. As well as, the deviation from stoichiometry, average heat of atomization, the overall mean bond energy and the glass transition temperature are also evaluated. All studied parameters are highly dependent on the Sb-ratio.