Structural and optical characterization of annealed As₃₀Te₆₀Ga₁₀ thin films prepared by thermal evaporation technique

Effect of annealing temperature on the structural and optical properties of As₃₀Te₆₀Ga₁₀ thin film was studied using various techniques such as differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The DSC analysis revealed that the As₃₀Te₆₀Ga₁₀ glass has a single glass transition and crystallization peak while XRD results confirmed that the as-prepared and annealed films have crystalline nature. The coexistence of the crystalline phases in the investigated films could be attributed to the formation of orthorhombic As, hexagonal Ga₇Te₁₀, and monoclinic As₂Te₃ phases. It was found that the average crystallite size and optical parameters of the studied films depend on the annealing temperature. For example, the optical band gap decreased from 1.54 eV to 1.11 eV as the annealing temperature increased from 300 K to 433 K.