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.
High n-type doping in germanium is essential for many electronic and optoelectronic applications especially for high performance Ohmic contacts, lasing and mid-infrared plasmonics. We report on the combination of in situ doping and excimer laser annealing to improve the activation of phosphorous in germanium. An activated n-doping concentration of 8.8??×??1019 cm?3 has been achieved starting from an incorporated phosphorous concentration of 1.1??×??1020 cm?3. Infrared reflectivity data fitted with a multi-layer Drude model indicate good uniformity over a 350?nm thick layer.
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