Hyperdoped Si nanocrystals embedded in silica for infrared plasmonics

We present the experimental realization of plasmonic hyperdoped Si nanocrystals embedded in silica via a combination of sequential low energy ion implantation and rapid thermal annealing. We show that phosphorus dopants are incorporated into the nanocrystal cores at concentrations up to six times higher than P solid solubility in bulk Si by combining 3D mapping with atom probe tomography and analytical transmission electron microscopy. We shed light on the origin of nanocrystal growth at high P doses, which we attribute to Si recoiling atoms generated in the matrix by P implantation, which likely increase Si diffusivity and feed the Si nanocrystals. We show that dopant activation enables partial nanocrystal surface passivation that can be completed by forming gas annealing. Such surface passivation is a critical step in the formation of plasmon resonance, especially for small nanocrystals. We find that the activation rate in these small doped Si nanocrystals is the same as in bulk Si under the same doping conditions.

Automated summary

We successfully demonstrate the experimental realization of plasmonic hyperdoped Si nanocrystals embedded in silica by a combination of sequential low energy ion implantation and rapid thermal annealing. We find that phosphorus dopants are incorporated into the nanocrystal cores at concentrations up to six times higher than P solid solubility in bulk Si. We explain the nanocrystal growth at high P doses as a result of Si recoiling atoms generated in the matrix by P implantation, which enhance Si diffusivity and provide the Si nanocrystals.