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Heavily doped semiconductor thin films are very promising for application in mid-infrared plasmonic devices because the real part of their dielectric function is negative and broadly tunable in the 5 to 50 μ m wavelength range at least. In this work, we investigate the electrodynamics of heavily n-type-doped germanium epilayers at infrared frequencies beyond the assumptions of the Drude model. The films are grown on silicon and germanium substrates, are in situ doped with phosphorous in the 10 17 to 10 19 cm− 3 range, then screened plasma frequencies in the 100 to 1200 cm− 1 range were observed. We employ infrared spectroscopy, pump-probe spectroscopy, and dc transport measurements to determine the tunability of the plasma frequency. Although no plasmonic structures have been realized in this work, we derive estimates of the decay time of mid-infrared plasmons and of their figures of merit for field …
American Physical Society
Publication date: 
15 Aug 2016

Jacopo Frigerio, Andrea Ballabio, Giovanni Isella, Emilie Sakat, Giovanni Pellegrini, Paolo Biagioni, Monica Bollani, Enrico Napolitani, Costanza Manganelli, Michele Virgilio, Alexander Grupp, Marco P Fischer, Daniele Brida, Kevin Gallacher, Douglas J Paul, Leonetta Baldassarre, Paolo Calvani, Valeria Giliberti, Alessandro Nucara, Michele Ortolani

Biblio References: 
Volume: 94 Issue: 8 Pages: 085202
Physical Review B