EXPLORING THE AMORPHOUS-TO-CRYSTALLINE PHASE TRANSITION IN Se80In5Te15−xBix CHALCOGENIDE THIN FILMS

This study reports the transition from the amorphous to the crystalline phase in quaternary Se₈₀In₅Te_15−xBi_x chalcogenide thin films prepared by controlled melt-quenching under a vacuum of 10⁻⁵ Torr. Nonisothermal DSC measurements were performed to confirm the amorphous as well as glassy states of the synthesized Se₈₀In₅Te_15−xBi_x alloys. For phase transformation, the thin films were thermally annealed for 2h at 343, 353, and 363K, after which Xray diffraction (XRD) and field emission scanning electron microscopy (FESEM) were used to characterize structural changes. Thermal annealing induced a substantial transformation from amorphous to crystalline morphology. With increasing annealing temperature, the luminescence peak showed a slight shift and an increase in intensity. The annealed films also exhibited higher absorption coefficients (α) and extinction coefficients (k), and a concomitant reduction in the optical band gap. The decrease in band gap with annealing temperature is attributed to the structural transition from the amorphous to the crystalline phase.