Engineering the Infrared Optical Response of Plasmonic Structures with ϵ‐Near‐Zero III‐V Semiconductors

Abstract

The pursuit for enhanced light‐matter interactions using ever more suitable plasmonic materials has led to the development of novel bulk materials, such as ϵ‐near‐zero (ENZ) media. The ability to control the free carrier density gives semiconductors a significant advantage over traditionally used noble metals and phonon‐based materials as ENZ media for infrared applications. A metal‐ENZ‐metal structure is designed of epitaxially‐grown III‐V semiconductors and patterned into nanoantennas by electron‐beam lithography (from 200 up to 1800 nm) and demonstrates plasmonic resonances tuned from the terahertz up to the near‐infrared, according to the ENZ doping level (1 × 1016, 1 × 1019, and 2 × 1019 cm‐3). Experimental results, corroborated by numerical simulations, show that the designed metal‐ENZ‐metal structure is a promising vehicle to provide additional insights regarding ENZ‐based phenomena including the resonance pinning, the near‐constant phase, and the dispersive nature of ENZ materials. It is believed that III‐V semiconductors within a metal‐ENZ‐metal structure address the problem of weak light‐matter interactions and shall greatly benefit infrared applications, e.g., sensing and communication, as they can be engineered to take advantage of both plasmon and ENZ effects and integrated onto modern photonics devices.