Effect of Substrate Temperature on the Properties of Eu-Doped SrSnO₃ Phosphor Thin Films Grown by Sputtering

Eu³⁺-doped SrSnO₃ (SrSnO₃:Eu³⁺) phosphor thin films are deposited on sapphire substrates by radio-frequency magnetron sputtering. The substrate temperature is varied from 25 to 400 °C. All SrSnO₃:Eu³⁺ films show amorphous behavior, while the band gap energies decrease with an increase in the substrate temperature and are determined to be 4.16-4.26 eV. The optical transmittance spectra exhibit an average transmittance of approximately 91% in the wavelength range 500-1100 nm; a gradual increase in emission intensity arising from the ⁵D₀→⁷F₂ transition (618 nm) of Eu³⁺ is observed with increasing substrate temperature. These results suggest that the optimum substrate temperature for depositing SrSnO₃:Eu³⁺ red-emitting phosphor thin films is 400 °C.