Ultrasmooth Patterned Metals for Plasmonics and Metamaterials

TLDR

Plasmonic devices promise advances in sensing, communications, and energy conversion, yet rough surfaces of deposited patterned metals hinder directional dry‑etching and limit performance. The authors deposit gold, silver, or copper onto patterned silicon, coat the metal with epoxy, and then peel it away, exploiting weaker adhesion to silicon to produce an ultra‑smooth surface. The resulting ultra‑smooth surfaces yield surface‑plasmon propagation lengths that approach the theoretical limits for perfectly flat films. Nagpal et al.

Abstract

Perfectly Flat? Plasmonic devices, which exploit the interactions of light with surface electrons, show great promise for applications in sensing, communications, and energy conversion. A key hindrance is the deposition of patterned metals used for plasmonics, because, as deposited, the terminal surfaces are rough and not amenable to patterning by directional dry-etching techniques. Nagpal et al. (p. 594 ) use patterned silicon substrates on which they add gold, silver, or copper and then apply an epoxy layer to the deposited metal. When pulled apart, the metal separates from the silicon, where the adhesion is poorer, leaving an ultra-smooth surface. The resulting surface plasmon propagation lengths approach the theoretical values for perfectly flat films.