title: Epitaxial superlattices with titanium nitride as a plasmonic component for optical hyperbolic metamaterials.
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, ultrathin 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.
authors.affiliation: School of Electrical and Computer Engineering, and Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907;
authors.forename: Gururaj V
authors.initials: GV
authors.lastname: Naik
authors.affiliation: School of Materials Engineering, and Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907;
authors.forename: Bivas
authors.initials: B
authors.lastname: Saha
authors.affiliation: Department of Agricultural and Biological Engineering, and Bindley Bioscience Center, Purdue University, West Lafayette, IN 47907; and.
authors.forename: Jing
authors.initials: J
authors.lastname: Liu
authors.affiliation: School of Materials Engineering, and Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907;
authors.forename: Sammy M
authors.initials: SM
authors.lastname: Saber
authors.affiliation: School of Materials Engineering, and Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907;
authors.forename: Eric A
authors.initials: EA
authors.lastname: Stach
authors.affiliation: Department of Agricultural and Biological Engineering, and Bindley Bioscience Center, Purdue University, West Lafayette, IN 47907; and.
authors.forename: Joseph M K
authors.initials: JM
authors.lastname: Irudayaraj
authors.affiliation: School of Electrical and Computer Engineering, and Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907;School of Materials Engineering, and Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907;
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Sands
authors.affiliation: School of Electrical and Computer Engineering, and Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907;
authors.forename: Vladimir M
authors.initials: VM
authors.lastname: Shalaev
authors.affiliation: School of Electrical and Computer Engineering, and Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907;DTU Fotonik, Department of Photonics Engineering, Technical University of Denmark, DK-2800 Lyngby, Denmark aeb@purdue.edu.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Boltasseva
mesh_terms: D004738:Engineering / Q000379:methods*; D006046:Gold / Q000737:chemistry; D008420:Manufactured Materials / Q000032:analysis*; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D055620:Optical Phenomena; D012834:Silver / Q000737:chemistry; D014025:Titanium / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D012834:Silver; C041500:titanium nitride; D006046:Gold; D014025:Titanium
keywords: ceramics; metal nitrides; refractory plasmonics