Enhanced photoluminescence of gallium phosphide by surface plasmon resonances of metallic nanoparticles

We report here enhanced photoluminescence (PL) from GaP, an indirect band gap semiconductor, by metallic Au and Ag nanoparticles. The metallic Au and Ag nanoparticles were sputtering-coated onto GaP followed by heat treatment. After optimization of the surface coverage ratios, we find 5.6-fold and 14.5-fold PL enhancement for the Au and Ag coated samples, respectively. Time resolved photoluminescence spectroscopy indicates that Ag nanoparticles can effectively accelerate the PL decay time. Our results indicate that the PL enhancement comes from enhanced photon scattering and localized field enhancement of metallic Au and Ag nanoparticles.