Ultraviolet penetration depth of phosphor Pr-doped Ca0.6Sr0.4TiO3 epitaxial film

Abstract

We elucidated the penetration depth of the ultraviolet excitation light for oxide-phosphor: Pr-doped Ca0.6Sr0.4TiO3 epitaxial film. Pr-doped Ca0.6Sr0.4TiO3 films with thicknesses of 50, 100, 200, 500, and 1000 nm were grown on single-crystal SrTiO3 (001) substrates. The penetration depth was estimated from the film-thickness dependence of photoluminescence intensities and analyzed by using the exponential Box-Lucas equation. It was found that Pr-doped Ca0.6Sr0.4TiO3 achieves nearly maximal intensity when the thickness is above approximately 200 nm. The combination of highly transparent oxide-phosphor films and the simple analysis make the precise measurement of penetration depth possible. This approach could be applicable to other phosphor ceramics. Our methods and results are quite helpful in the fundamental technologies for information devices and security printings, and also realizes significant resource savings of rare-earth ions.