Photo- and cathodoluminescence characteristics of blue-light-emitting epitaxial Sr2CeO4 thin-film phosphors

Orthorhombic epitaxial ${\mathrm{Sr}}_{\mathrm{2}}{\mathrm{CeO}}_4$ thin-film phosphors were grown on (100) ${\mathrm{SrTiO}}_3$ and yttria-stabilized-zirconia (YSZ) single crystal substrates with epitaxial relationships of (100) ${\text{[010]}}_{{\mathrm{Sr}}_{\mathrm{2}}{\mathrm{CeO}}_{\mathrm{4}}}{\mathrm{//(100)[010]}}_{{\mathrm{SrTiO}}_3}$ and ${\text{(100)[010]}}_{{\mathrm{Sr}}_{\mathrm{2}}{\mathrm{CeO}}_{\mathrm{4}}}{\mathrm{//(100)[011]}}_{\mathrm{YSZ}},$ respectively. As-deposited films exhibit a broadband photoluminescence (PL) emission, peaking at about 477–481 nm with a maximum cathodoluminescence (CL) intensity at about 465 nm. Enhanced PL intensity was observed for the films deposited on (100) YSZ and ${\mathrm{SrTiO}}_3$ substrates as compared to deposits on $c$ -plane sapphire substrates, correlating with improved intragranular crystallinity and reducing defects via epitaxy. Postannealing in air significantly enhanced both of the PL and CL intensities. Luminous efficiency of 0.14 lm/W at 1 kV and 22 $\mu {\mathrm{A/cm}}^2$ was observed for a 2-μm-thick film annealed at 1000 °C in air.