Low-loss plasmonic resonances in heavily doped InAs for infrared optoelectronics integration

Plasmonic resonances supported by traditional metals (e.g., gold, silver, and aluminum) have been used to enhance optoelectronic devices such as emitters and detectors.[1] However, these materials are very lossy in the infrared region, hindering their use in actual devices that operate in the infrared.[2] To overcome this issue, we use doped III-V semiconductors as a low-loss plasmonic material that can be easily integrated with traditional III-V infrared optoelectronic devices. Here we show that an InAs epilayer, when highly-doped with Tellurium (up to 10²⁰ cm^-3), exhibits a plasma frequency corresponding to light at a free-space wavelength of 4.5 microns. When a 1D grating with period < 5 μm is formed in the epilayer via dry etching, resonances at longer wavelengths (5.5 to 14 microns) are observed with quality factors around 7 and absorption as high as 95%. Finite element electromagnetic models of the resonance modes show good agreement with our experimental results. This work was funded by OSD Contract No: W911NF-22-P-0024 administered by ARO.

[1] J.A. Nolde et al., “Resonant quantum efficiency enhancement of midwave infrared nBn photodetectors using one-dimensional plasmonic gratings”, Appl. Phys. Lett. 106, (2015) 261109

[2] N. Kinsey et al., “Near-Zero-Index Materials for Photonics,” Nature Materials 4 (2019) 742.