Influence of Preparation Ambient on Luminescent and Electrical Properties of TiO₂:Sm Thin Films

This study investigates the effects of different fabrication and annealing atmospheres on the properties of samarium (Sm)-doped titanium dioxide (TiO₂:Sm) thin films, with a focus on luminescence and electrical conductivity. TiO₂:Sm thin films are deposited by laser ablation and annealed at 700 °C in O₂ and H₂ + N₂ atmospheres. X-ray diffraction analysis shows that fabrication and annealing in the H₂ + N₂ atmosphere significantly inhibit crystal growth. PL spectra reveal that films fabricated and annealed in O₂ exhibit the strongest luminescence, while those in the H₂ + N₂ show quenched luminescence. X-ray absorption fine structure results indicate that Sm³⁺ ions in the non-luminescent samples have a high-symmetry oxygen coordination, which is unfavorable for luminescence. C–V and I–V measurements reveal a substantial increase in electrical conductivity for films fabricated and annealed in H₂ + N₂, attributed to the incorporation of hydrogen and the formation of oxygen vacancies. This study concludes that while the fabrication and annealing in the H₂ + N₂ atmospheres enhance the electrical conductivity of TiO₂:Sm thin films, they also degrade luminescence. Balancing luminescence intensity and electrical conductivity is crucial for the optical device application of TiO₂:Sm thin films. It is necessary to carefully adjust the fabrication and annealing conditions to enhance electrical conductivity while maintaining strong luminescence.