Polar Semiconducting Scandium Nitride as an Infrared Plasmon and Phonon-Polaritonic Material.

Maurya, Krishna Chand; Rao, Dheemahi; Acharya, Shashidhara; Rao, Pavithra; Pillai, Ashalatha Indiradevi Kamalasanan; Selvaraja, Shankar Kumar; Garbrecht, Magnus; Saha, Bivas · Nano Lett · 2022

basic_science · Level V

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Abstract

The interaction of light with collective charge oscillations, called plasmon-polariton, and with polar lattice vibrations, called phonon-polariton, are essential for confining light at deep subwavelength dimensions and achieving strong resonances. Traditionally, doped-semiconductors and conducting metal oxides (CMO) are used to achieve plasmon-polaritons in the near-to-mid infrared (IR), while polar dielectrics are utilized for realizing phonon-polaritons in the long-wavelength IR (LWIR) spectral regions. However, demonstrating low-loss plasmon- and phonon-polaritons in one host material will make it attractive for practical applications. Here, we demonstrate high-quality tunable short-wavelength IR (SWIR) plasmon-polariton and LWIR phonon-polariton in complementary metal-oxide-semiconductor compatible group III-V polar semiconducting scandium nitride (ScN) thin films. We achieve both resonances by utilizing <i>n</i>-type (oxygen) and <i>p</i>-type (magnesium) doping in ScN that allows modulation of carrier concentration from 5 × 10<sup>18</sup> to 1.6 × 10<sup>21</sup> cm<sup>-3</sup>. Our work enables infrared nanophotonics with an epitaxial group III semiconducting nitride, opening the possibility for practical applications.