This paper describes the design and prototyping of single-crystalline TiN plasmonic metasurfaces based on subwavelength hole arrays. An evolutionary algorithm with a multiobjective fitness function was developed to produce a variety of threedimensional (3D) light profiles with balanced intensities at the light spots. We also demonstrated a simple, efficient technique to prototype these lattice designs in large-area TiN films by combining focused ion beam milling and wet chemical etching. Multilevel phase control was achieved by tuning nanohole size, and multipoint focusing with arbitrary light spot patterns was realized. Using anisotropic nanohole shapes, the TiN lattice lenses could exhibit dynamic tuning of the focal profiles by changing the polarization of incident light.

Magnetron sputter-deposited TiBx films grown from TiB2 targets are typically highly overstoichiometric with x ranging from 3.5 to 2.4 due to differences in Ti and B preferential ejection angles and gas-phase scattering during transport between the target and the substrate. The authors show that the use of highly magnetically unbalanced magnetron sputtering leads to selective ionization of sputter-ejected Ti atoms which are steered via an external magnetic field to the film, thus establishing control of the B/Ti ratio with the ability to obtain stoichiometric TiB2 films over a wide range in Ar sputtering pressures.

Titanium nitride (TiN) is a mechanically robust, high-temperature stable, metallic material receiving considerable attention for resilient plasmonics. In this work, the authors fabricated six heteroepitaxial TiN films on sapphire using controllably unbalanced reactive magnetron sputtering. They examined the effect of substrate growth temperature on the plasmonic and crystalline quality of the film. Optical properties of all films were obtained from spectroscopic ellipsometry; plasmonic quality factors were determined from the real and imaginary parts of the dielectric function. The authors determined crystallinity using x-ray diffraction and surface morphology using atomic force microscopy. X-ray diffraction showed (111) TiN peaks with Pendellösung fringes indicating consistent heteroepitaxy. Atomic force microscopy showed smooth surfaces with root mean square surface roughness ranging from 0.2 to 2.6 nm. Based on this characterization, the authors determined that the substrate deposition temperature of 550 °C yielded (111)-oriented heteroepitaxial TiN with minimal surface roughness. The authors found that 550 °C also gave highest plasmonic quality factors for all wavelengths, approaching the values of today's best plasmonic materials (such as Au and Ag). Further, the Q-factors at wavelength 1550 nm inversely correlated with calculated lattice constants. Their results indicate that the plasmonic response of TiN is directly linked with structural quality of the film.

The characteristics of continuous-wave millimeter-wave/terahertz radars make them candidates to remotely sense the physiological parameters of individuals, such as respiration and heart rates. The characteristics of these radars include transmission through the atmosphere and clothing, well-collimated beams, and sensitivity to small displacements. The directional Doppler velocity can be used to measure the movement of a subject's chest wall due to respiration and the more subtle motion of the body due to the cardiopulmonary system. We will present an overview of two systems that have been developed along with representative data from each.

Variability remains the principal concern for commercialization of HfO2 based resistance switching devices. Here, we investigate the role of thermal processing conditions on internal structure of atomic layer deposited HfO2 thin films, and the impact of that structure on filament forming kinetics of p+ Si/HfO2/Cu and TiN/HfO2/Cu devices. Regardless of bias polarity or electrode metal, filament formation times are at least one order of magnitude shorter in polycrystalline than in amorphous films, which we attribute to the presence of fast ion migration along grain boundaries. Within polycrystalline films, filament formation times are correlated with degree of crystalline orientation. Inter-device variability in forming time is roughly equivalent across HfO2 film processing conditions. The kinetics of filament forming are shown to be highly dependent on HfO2 microstructure, with possible implications for the inter-device variability of subsequent switching cycles.