Epitaxial superlattices with titanium nitride as a plasmonic component for optical hyperbolic metamaterials

Gururaj V. Naik, Bivas Saha, Jing Liu, Sammy M. Saber, Eric A. Stach, Joseph M.K. Irudayaraj, Timothy D. Sands, Vladimir M. Shalaev, Alexandra Boltasseva

Research output: Contribution to journalArticlepeer-review

Abstract

Titanium nitride (TiN) is a plasmonic material having optical properties resembling gold. Unlike gold, however, TiN is complementary metal oxide semiconductor-compatible, mechanically strong, and thermally stable at higher temperatures. Additionally, TiN exhibits low-index surfaces with surface energies that are lower than those of the noble metals which facilitates the growth of smooth, ultra-thin crystalline films. Such films are crucial in constructing low-loss, high-performance plasmonic and metamaterial devices including hyperbolic metamaterials (HMMs). HMMs have been shown to exhibit exotic optical properties, including extremely high broadband photonic densities of states (PDOS), which are useful in quantum plasmonic applications. However, the extent to which the exotic properties of HMMs can be realized has been seriously limited by fabrication constraints and material properties. Here, we address these issues by realizing an epitaxial superlattice as an HMM. The superlattice consists of ultrasmooth layers as thin as 5 nm and exhibits sharp interfaces which are essential for high-quality HMM devices. Our study reveals that such a TiN-based superlattice HMM provides a higher PDOS enhancement than gold-or silver-based HMMs.

Original languageEnglish (US)
Pages (from-to)7546-7551
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume111
Issue number21
DOIs
StatePublished - May 27 2014
Externally publishedYes

Keywords

  • Ceramics
  • Metal nitrides
  • Refractory plasmonics

ASJC Scopus subject areas

  • General

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