Mid-Infrared Sensing Using Heavily Doped Germanium Plasmonics on Silicon Substrates

Heavily-doped semiconductor films are very promising for applications in mid-infrared plasmonic devices because the real part of their dielectric function is negative and broadly tunable in this wavelength range. In this work, we investigate, n-type doped Ge epilayers grown on Si substrates. We design and realize Ge nano-antennas on Si substrates demonstrating the presence of localized plasmon resonances, and exploit them for molecular sensing in the mid-infrared.