Heavily-doped germanium on silicon with activated doping exceeding 1020 cm−3 as an alternative to gold for mid-infrared plasmonics

Ge-on-Si has been demonstrated as a platform for Si foundry compatible plasmonics. We use laser thermal annealing to demonstrate activated doping levels >10²⁰ cm^-3 which allows most of the 3 to 20 μm mid-infrared sensing window to be covered with enhancements comparable to gold plasmonics.