Photoluminescence of silicon nanorods via plasmonic gold nanopore arrays

Silicon luminescence remains a significant challenge, and its origin is intense debate ever since. Here we show, for the first time, a luminescent strategy involving silicon nanorods coupled with plasmonic gold nanopore arrays. It is demonstrated that the luminescence intensity of silicon nanorods induced by plasmonic gold nanopore arrays is nine times higher than that of pure silicon nanorod samples. Despite the absence of an insulating spacer between the gold nanopore arrays and silicon nanorods, no luminescence quenching is observed. Furthermore, we employ finite difference time domain simulations to map the electric field distribution and estimate a Purcell factor of 5, which is lower than the experimentally measured luminescence enhancement. This indicates that the observed luminescence enhancement is only partially attributable to the Purcell effect. Importantly, the Purcell effect would not cause a shift in the luminescence peak, whereas a significant peak shift is observed in our experiments. Based on these facts, a novel luminescence mechanism is proposed to complementally account for the remarkable luminescence enhancement observed in our experiments. Plasmonic gold nanopore arrays-induced energy level splitting may appear in silicon nanorods, which generates a localized direct bandgap, thereby yielding enhanced visible light emission.