Fabrication and characterization of Bi-doped Y₂O₃ phosphor thin films by RF magnetron sputtering

Bi-doped Y₂O₃ phosphor thin films were fabricated by RF magnetron sputtering and their photoluminescence (PL) emission characteristics were systematically investigated depending on substrate temperature, film thickness, and Bi^{3 +} ion concentration. Visible PL emission via ³P₁→¹S₀ transition of Bi^{3 +} ions could be observed by ultraviolet light excitation and its intensity was increased with increasing the substrate temperature and the film thickness. This is due to enhancement of the film crystallinity with increasing substrate temperature and film thickness and due to interaction volume increase with increasing the film thickness. However, PL intensity had the maximum value with Bi^{3 +} ion concentration of 1.09 at.% owing to concentration quenching effect. These films showed high transmittance of above 95% in the visible and near-infrared region and had refractive index of 1.87 ~ 1.97 depending on the wavelength. These results show the potential of Bi-doped Y₂O₃ phosphor thin films not only as a spectrum converting layer but also as an antireflective coating layer in crystalline Si solar cells, considering that refractive index of the Bi-doped Y₂O₃ film is nearly similar to that of silicon nitride film.