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Description
Ba₀.₅Sr₀.₅TiO₃ (BST) thin films have attracted considerable attention for optoelectronic and sensing applications owing to their tunable optical characteristics. This study investigates the effect of manganese (Mn) doping on the optical properties of BST thin films with Mn concentrations of 0.0, 0.5, and 1.0 wt.%. The thin films were synthesized using the Chemical Solution Deposition (CSD) method and deposited onto p-type Si(100) substrates. Film thickness and optical properties were evaluated to determine the influence of Mn incorporation on the electronic structure of the BST films. The average thickness increased from 12.70 nm for the undoped BST film to 17.29 nm and 31.28 nm for the 0.5 wt.% and 1.0 wt.% Mn-doped films, respectively, indicating enhanced film growth with increasing Mn concentration. Optical analysis revealed that the band gap energy increased from 2.50 ± 0.51 eV for the undoped film to 3.15 ± 0.10 eV at 0.5 wt.% Mn, followed by a decrease to 2.29 ± 0.25 eV at 1.0 wt.% Mn. Conversely, the Urbach energy decreased from 0.16 ± 0.04 eV to 0.13 ± 0.04 eV at 0.5 wt.% Mn, suggesting reduced structural disorder, before increasing to 0.24 ± 0.07 eV at 1.0 wt.% Mn due to increased defect states. These findings demonstrate that Mn doping significantly modifies the optical characteristics of BST thin films by influencing the optical band gap and structural disorder. The observed variations indicate that Mn incorporation effectively alters the electronic structure of BST, highlighting its potential for tailoring the material properties for future optoelectronic and optical sensing applications.
Keywords: Band gap; Ba₀.₅Sr₀.₅TiO₃ thin film; Chemical Solution Deposition; Manganese doping; Urbach energy.
