Common computer-chip silicon can now manipulate infrared light without needing any expensive nanoscale etching.
Plasmons are ripples of electrons that allow us to control light at the nanoscale, but they usually require carving intricate patterns into gold or silver. This research found that the natural boundaries between grains in unpatterned silicon can create these same effects for infrared light. This means we can turn cheap, everyday silicon into high-end optical sensors just by over-doping it with impurities. It removes the need for billion-dollar cleanrooms to make advanced thermal-imaging tools. This discovery could make everything from night-vision goggles to chemical sensors incredibly cheap and easy to mass-produce. It puts powerful light-manipulation technology into the hands of anyone with basic semiconductor tools.
Emergence of Localized Surface Plasmons in Unpatterned Hyperdoped Polycrystalline Silicon
arXiv · 2605.04854
The ability to engineer localized surface plasmon resonances at large scale usually relies on precise nanoscale patterning. Here, we demonstrate that mid-infrared plasmonic responses can instead emerge in unpatterned polysilicon films composed of nanometric (5-50 nm) grains, challenging established design paradigms and eliminating the need for external nanostructuring. Using tailored out-of-equilibrium annealing conditions, we show that hyperdoped polysilicon layers exhibit enhanced light-matter