Strong photoluminescence enhancement of silicon quantum dots by their near-resonant coupling with multi-polar plasmonic hot spots.

Localization of quantum dots (QDs) in the vicinity of metal nanoparticles (NPs) is known as one of the most efficient ways to increase their photoluminescence (PL). Despite the important recent advances achieved in II-VI QDs, only a seven-fold plasmon-induced PL enhancement is reported for Si QDs. In our paper we show that the plasmon-induced strong local PL enhancement of Si QDs in an SiN matrix can reach a 60-fold gain level. This important result was achieved on original tunable "nano-Ag/SiN(X)" plasmonic structures. In particular, we show that (i) localization of Si QDs in hot spot regions created by several randomly arranged Ag NPs and (ii) careful tuning of the multi-polar plasmon bands of Ag NPs to match resonant absorption and emission wavelengths of Si QDs, lead to the important enhancement of their PL intensity.