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

Orthorhombic epitaxial $Sr2CeO4$ thin-film phosphors were grown on (100) $SrTiO3$ and yttria-stabilized-zirconia (YSZ) single crystal substrates with epitaxial relationships of (100) $[010]Sr2CeO4//(100)[010]SrTiO3$ and $(100)[010]Sr2CeO4//(100)[011]YSZ,$ 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 $SrTiO3$ 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 $μA/cm2$ was observed for a 2-μm-thick film annealed at 1000 °C in air.