TERAHERTZ RESONATOR

A tunable terahertz resonator includes a semiconductor Substrate and a metal layer contacting a surface of the semiconductor substrate. A depletion layer is formed in the semiconductor substrate near an interface between the metal layer and the semiconductor Substrate. A chiral nanostructure is coupled to the substrate or the metal layer, the chiral nanostructure including a conducting or semiconducting material and having an inductance. A bias circuit applies a bias Voltage across the metal layer and the semiconductor Substrate to control a capacitance of a tunable capacitor that includes the depletion layer. The chiral nanostructure and the tunable capacitor form a tunable resonant circuit. The tunable terahertz resonator can be used in a terahertz radiation emitter or receiver

POLARIZATION-COUPLED FERROELECTRIC UNPOLARUNCTION MEMORY AND ENERGY STORAGE DEVICE

A memory device is provided. The memory device includes a plurality of memory cells and a controller to write data to and read data from the memory cells. Each memory cell includes a first semiconductor material having a spontaneous polarization, a resistive ferroelectric material having a switchable spontaneous polarization, and a second semiconductor material having a spontaneous polarization, the resistive ferroelectric material being positioned between and in contact with the first and second semiconductor materials. The memory device can be configured to store energy that can be released by applying a voltage pulse to the memory device

Empirical Correction for Spectroscopic Ellipsometric Measurements of Rough or Textured Surfaces

A method of applying spectroscopic ellipsometry to arrive at accurate values of optical and physical properties for thin films on samples having rough or textured surfaces

Band-to-band transitions, selection rules, effective mass and exciton binding energy parameters in monoclinic \beta-Ga2O3

We employ an eigen polarization model including the description of direction dependent excitonic effects for rendering critical point structures within the dielectric function tensor of monoclinic \beta-Ga2O3 yielding a comprehensive analysis of generalized ellipsometry data obtained from 0.75 eV--9 eV. The eigen polarization model permits complete description of the dielectric response, and we obtain single-electron and excitonic band-to-band transition anisotropic critical point structure model parameters including their polarization eigenvectors within the monoclinic lattice. We compare our experimental analysis with results from density functional theory calculations performed using a recently proposed Gaussian-attenuation-Perdue-Burke-Ernzerhof hybrid density functional, and we present and discuss the order of the fundamental direct band-to-band transitions and their polarization selection rules, the electron and hole effective mass parameters for the three lowest band-to-band transitions, and their exciton binding energy parameters, in excellent agreement with our experimental results. We find that the effective masses for holes are highly anisotropic and correlate with the selection rules for the fundamental band-to-band transitions, where the observed transitions are polarized closely in the direction of the lowest hole effective mass for the valence band participating in the transition

COMBINED USE OF OSCILLATING MEANS AND ELLIPSOMETRY TO DETERMINE UNCORRELATED EFFECTIVE THICKNESS AND OPTICAL CONSTANTS OF MATERIAL DEPOSITED AT OR ETCHED FROM A WORKING ELECTRODE THAT PREFERRABLY COMPRISES NON - NORMAL ORIENTED NANOFIBERS

Disclosed are systems and methods that enable determination of uncorrelated thickness of a working electrode and surface region optical constants in settings involving electrochemical processing at a working electrodes in a Piezo electric Balance system , by simultaneous application of an Ellipsometer system , the working electrode optionally having a multiplicity of nanofibers that are oriented non normally to a surface of said working electrode . Further disclosed is , simultaneous with said determinations , the monitoring of electrochemical processes at a piezoelectric balance working electrode driven by electrical energy applied between said working electrode and counter electrode

Critical-point model dielectric function analysis of WO3 thin films deposited by atomic layer deposition techniques

WO3 thin films were grown by atomic layer deposition and spectroscopic ellipsometry data gathered in the photon energy range of 0.72-8.5 eV and from multiple samples was utilized to determine the frequency dependent complex-valued isotropic dielectric function for WO3. We employ a critical-point model dielectric function analysis and determine a parameterized set of oscillators and compare the observed critical-point contributions with the vertical transition energy distribution found within the band structure of WO3 calculated by density functional theory. We investigate surface roughness with atomic force microscopy and compare to ellipsometric determined effective roughness layer thickness

Electrical properties of ZnO–BaTiO3–ZnO heterostructures with asymmetric interface charge distribution

We report on capacitance-voltage, current-voltage, Sawyer–Tower, and transient current switching measurements for a ZnO–BaTiO3–ZnO heterostructure deposited on (001) silicon by using pulsed laser deposition. The triple-layer structure reveals asymmetric capacitance- and current-voltage hysteresis and cycling-voltage dependent Sawyer–Tower polarization drift. We explain our findings by coupling of the ferroelectric (BaTiO3) and piezoelectric (ZnO) interface charges and parallel polarization orientation of the ZnO layers causing asymmetric space charge region formation under positive and negative bias. The transient current characteristics suggest use of this structure as nonvolatile memory device

TERAHERTZ-INFRARED ELLIPSOMETER SYSTEM, AND METHOD OF USE

The present invention relates to ellipsometer and polarimeter systems, and more particularly is an ellipsometer or polarimeter or the like system which operates in a frequency range between 300 GHz or lower and extending to higher than at least 1 Tera-hertz (THz), and preferably through the Infra-red (IR) range up Sh and his th. 100 THz, including: a Source Such as a backward wave oscillator, a Smith-Purcell cell; a free electron laser, or an FTIR source and a solid state device; and a detector Such as a Golay cell; abolometer or a solid state detector: and preferably including a polarization state generator comprising: an odd bounce image rotating system and a polarizer, or two polarizers; and optionally including least one compensator and/or modulator, in addition to an analyzer

Anisotropy, band-to-band transitions, phonon modes, and oxidation properties of cobalt-oxide core-shell slanted columnar thin films

Highly ordered and spatially coherent cobalt slanted columnar thin films (SCTFs) were deposited by glancing angle deposition onto silicon substrates, and subsequently oxidized by annealing at 475°C. Scanning electron microscopy, Raman scattering, generalized ellipsometry, and density functional theory investigations reveal shape-invariant transformation of the slanted nanocolumns from metallic to transparent metal-oxide core-shell structures with properties characteristic of spinel cobalt oxide. We find passivation of Co-SCTFs yielding Co-Al2O3core-shell structures produced by conformal deposition of a few nanometers of alumina using atomic layer deposition fully prevents cobalt oxidation in ambient and from annealing up to 475°C