Addressing the Impact of Surface Roughness on Epsilon-Near-Zero Silicon Carbide Substrates

David Navajas; José M Pérez-Escudero; María Elena Martínez-Hernández; Javier Goicoechea; Iñigo Liberal

doi:10.1021/acsphotonics.3c00476

Addressing the Impact of Surface Roughness on Epsilon-Near-Zero Silicon Carbide Substrates

ACS Photonics. 2023 Aug 22;10(9):3105-3114. doi: 10.1021/acsphotonics.3c00476. eCollection 2023 Sep 20.

Authors

David Navajas¹, José M Pérez-Escudero¹, María Elena Martínez-Hernández¹, Javier Goicoechea¹, Iñigo Liberal¹

Affiliation

¹ Department of Electrical, Electronic and Communications Engineering, Institute of Smart Cities (ISC), Public University of Navarre (UPNA), 31006 Pamplona, Spain.

Abstract

Epsilon-near-zero (ENZ) media have been very actively investigated due to their unconventional wave phenomena and strengthened nonlinear response. However, the technological impact of ENZ media will be determined by the quality of realistic ENZ materials, including material loss and surface roughness. Here, we provide a comprehensive experimental study of the impact of surface roughness on ENZ substrates. Using silicon carbide (SiC) substrates with artificially induced roughness, we analyze samples whose roughness ranges from a few to hundreds of nanometer size scales. It is concluded that ENZ substrates with roughness in the few nanometer scale are negatively affected by coupling to longitudinal phonons and strong ENZ fields normal to the surface. On the other hand, when the roughness is in the hundreds of nanometers scale, the ENZ band is found to be more robust than dielectric and surface phonon polariton (SPhP) bands.