Up-Conversion Photoluminescence Reconfiguration in Silicon by Inner Microstructure Control of Hybrid Plasmonic-Semiconductor Nanoparticles

Hybrid metal–semiconductor nanostructures unifying plasmonic and high-refractive-index materials in a single resonant system demonstrate a wide set of unique optical properties. Such systems are a perspective for a broad palette of applications, but the link between their inner structure and optical properties is a very sensitive issue, which is still not revealed. Here, we describe the influence of internal microstructure of a hybrid gold–silicon nanoparticle (the gold nanoparticle with embedded silicon nanograins) on the up-conversion white-light photoluminescence. The evolution in the internal microstructure of the system during thermal treatment up to 500 °C is tracked in situ through the HAADF and EDS STEM techniques. The studies show the redistribution of the materials inside the hybrid nanoparticle and the reduction of the silicon nanograin numbers under heating without an external modification of the nanoparticle shape. We have established numerically that the dependence of the enhancement factor spectral width on the S/V ratio of the nanoparticle plasmonic component is close to the linear behavior. The shrinkage of the photoluminescence spectrum (up to 42%) of the hybrid nanoparticle reconfigured by laser exposure and thermal treatment is shown experimentally, which supports our numerical conclusions. The results shed light on the connection of optical properties of complex hybrid systems with their complex internal composition, providing a powerful tool to control their optical properties through microstructure rearrangement. They also open the way to the development of reconfigurable silicon-based up-conversion light nanosources for integrated optical devices and biophotonics.