Oral: Low-loss tunable plasmonic resonances in heavily doped InAs for infrared optoelectronic devices

Plasmonic enhancements of optoelectronic devices, such as emitters and detectors, have traditionally used metals like gold, silver, and aluminum. However, metals are susceptible to high losses in the infrared region, limiting their usefulness for infrared devices. We overcome this problem through use of heavily doped III-V semiconductors to produce low-loss plasmonic layers that can be monolithically integrated with traditional III-V infrared optoelectronic devices during epitaxial growth. We show that a heavily tellurium-doped (N_D = 7×10¹⁹ cm^-3) indium arsenide (InAs) epilayer exhibits a plasma frequency that corresponds to a wavelength of 4.5 µm. We fabricated one-dimensional gratings with several pitches and linewidths up to 5 µm via photolithography and dry etching. Reflection measurements using a Fourier transform infrared (FTIR) spectrometer equipped with an infrared microscope show several plasmonic resonances with up to 95% absorption and quality factors around 7. Electromagnetic models based on finite element solvers provide confirmation of the experimental results, demonstrating tunable low-loss resonances for infrared optoelectrical devices.