Benchmarking the Use of Heavily Doped Ge for Plasmonics and Sensing in the Mid-Infrared

Despite the recent introduction of heavily doped semiconductors for mid-infrared plasmonics, it still remains an open issue whether such materials can compete with noble metals. A whole set of figures of merit are employed to thoroughly assess the use of heavily doped Ge on Si as a mid-infrared plasmonic material and benchmark it against standard noble metals such as Au. A full-wave electrodynamics framework is used to model and design high-performance, silicon-foundry compatible mid-infrared plasmonic sensors based on experimental material data reaching plasma wavelengths down to lambda(p) similar to 3.1 mu m. It is finally shown that Ge sensors can provide signal enhancements for vibrational spectroscopy above the 3 orders of magnitude, thus, representing a promising alternative to noble metals, leveraging the full compatibility with the silicon foundry microfabrication processes.