Europium activated yttrium oxide(Eu:Y2O3)phosphor films have been grownin situon (100) bare and diamond-coated silicon substrates using a pulsed laser deposition technique. Diamond-coated silicon substrates were prepared using hot filament chemical vapor deposition of diamond onto silicon. Photoluminescence brightness fromEu:Y2O3films grown at 700 °C on diamond-coated silicon substrates was about twice that of films on bare silicon, and reached 80&percent; of the brightness of powders. The higher brightness fromEu:Y2O3film on diamond-coated silicon substrates is attributed to reduced internal reflections from theEu:Y2O3film surface, which results from the roughness of the diamond layer. ©1997 American Institute of Physics.