Structural and optical properties of Se85-xTe15Inx chalcogenide thin films for optoelectronics

In the present work, different compositions of Se85-xTe15Inx (x=0, 2, 4, 6, 8, 10 at %) chalcogenide glass were synthesized by rabid quenching of the melt. Optical characterization of thermally evaporated thin film of these compositions was performed. The thickness and first approximate values of refractive index were deduced by the well-known Swanepoel model. The results refer to the increase in refractive index and the dielectric constants with increasing the indium contents within these compositions which were discussed by the increased polarizability of indium in comparison with selenium. Energy gap values of these films estimated according to a good fitting to Tauc allowed non-direct transition. It was found that the energy gap decreases with increasing indium contents within the specimens. The results were discussed in view of chemical bond approach and electronegativity difference of the elements involved.