Host Lattice-Excitation-Enhanced Photoluminescence in Eu³⁺-Doped LaInO₃ Epitaxial Films

Abstract

Oxide-phosphor epitaxial films having a large lattice mismatch with the substrate may significantly alter the photoluminescence (PL) properties of the bulk or powder. We investigated the PL characteristics of phosphor Eu0.10La0.90InO3 (ELIO; lattice mismatch of approximately 5–7% with SrTiO3 (STO)) epitaxially grown on an STO single crystal (001). X-ray diffraction patterns indicated that the ELIO epitaxial film on STO (001) formed a 90° domain with a size of tens of nanometers and underwent 4.62% lattice expansion. Intense orange-red luminescence was observed from the ELIO epitaxial film under ultraviolet excitation, similar to the case of the ELIO powder. The PL excitation spectra indicated that host lattice (HL) excitation, rather than charge-transfer excitation, led to the red luminescence in the ELIO epitaxial film, in contrast to that in the ELIO powder. The efficient HL excitation in the ELIO epitaxial film will be advantageous for the fabrication of thin-film-type EL devices with an ELIO emitting layer.