Localized surface plasmon-enhanced photoluminescence of amorphous silicon quantum dots through plasmonic subwavelength crossed metallic gratings

Abstract

We investigate experimentally the enhancing effect of plasmonic subwavelength crossed Ag gratings on photoluminescence (PL) from the amorphous silicon quantum dots (a-Si QDs) embedded in a central silicon-rich SiOx film of the Ag/SiOx:a-Si QDs/Ag sandwich nanostructures. The use of the crossed Ag grating structure as the top layer in the sandwich nanostructures results in a 2-fold increase in the PL peak intensity and a 1.34-fold increase in the integrated emission intensity compared with the use of a one-dimensional (1D) Ag grating top layer, and a 1.53-fold peak intensity increase compared with that of a SiOx:a-Si QDs/Ag structure without a Ag top layer. These significant PL enhancements can be attributed to the high light-extraction efficiency of the polarization-independent crossed metallic grating structure, the strong out-coupling of localized surface plasmons (LSPs), and the strong a-Si QD–LSP coupling.