Plasmonic gratings of different periodicities are fabricated on top of silicon nanocrystals embedded in silicon dioxide. Total enhancements of up to 2 were observed, which matches the value from simulations. Plasmonic enhancements are observed for the first three orders of the plasmonic modes, with the peak enhancement wavelength varying with the periodicity. Biharmonic gratings are also fabricated to extract the enhanced emission from the first order plasmonic mode, resulting in enhancements with quality factors of up to 16. © 2009 American Institute of Physics.