Showing papers by "Jon Paul Maria published in 2006"

Surface plasmon resonance in conducting metal oxides

Abstract: We report the initial observation of surface plasmon resonance (SPR) in a conducting metal oxide thin film. The SPR phenomenon has been observed by attenuated total reflection of near-infrared radiation and is in agreement with electron energy loss spectroscopy measurements. To date, only metals are known to exhibit surface plasmon resonance and only noble metals have practical application. According to theory SPR should be observable in any conductor. This theoretical prediction is verified in the present study. The compositions of many conducting metal oxides are systematically variable, suggesting a significant advance in thin film characterization and innovative possibilities for versatile and sensitive chemical sensing applications.

MgO epitaxy on GaN (0002) surfaces by molecular beam epitaxy

Abstract: We report on the epitaxial deposition of magnesium oxide films with [111] crystallographic orientation on (0002) GaN by molecular beam epitaxy. Specifically, we use an adsorption controlled growth mechanism to initiate the growth process. Electron diffraction shows a spotty intense pattern without intensity fluctuations during growth and evidence of in-plane twinning. X-ray diffraction reveals the films to be epitaxial with full width at half maximum values of 0.3°, 0.5°, and 1° in 2θ, ϕ, and χ circles, respectively. Wet etching of the GaN surface with a HCl:HF mixture prior to growth is critical for achieving high crystalline quality. Epitaxial growth is observed between room temperature and 650°C, with negligible changes in crystalline quality with increased temperature. Atomic force microscopy analysis shows grainy surfaces with feature sizes near 10nm and rms roughness values of 1.4A over 1μm2 areas. X-ray diffraction analysis suggests MgO film stability up to 850°C in ex situ air annealing.

Discrete Barium Strontium Titanate (BST) Thin-Film Interdigital Varactors on Alumina: Design, Fabrication, Characterization, and Applications

Abstract: Discrete barium strontium titanate (BST) thin-film capacitors in industry standard 0603 footprint are introduced and characterized. BST capacitors have a voltage-dependent permittivity, enabling BST thin-film capacitors to be used as tuning elements in frequency agile devices. The capacitance changed by 1.5:1 at 35 V (116 kV/cm) bias. The temperature dependence of the capacitance was measured to be less than plusmn 20 % from -100 degC to +100 degC. A 2nd-order tunable combline bandpass filter on FR4 substrate has been implemented using the discrete BST varactors. The filter showed a center frequency tuning of 22% from 2.14 GHz to 2.61 GHz upon application of 130 V (433 kV/cm) bias. The zero-bias insertion loss was 4.9 dB which decreased to 2.9 dB at the high bias state. The return loss was better than 11 dB over the tuning range. Nonlinear characterization of the filter using two-tone test and a digitally-modulated CDMA 2000 signal showed an IP3 of +32 dBm and an ACPR of better than -50 dBc up to 26 dBm of input power, respectively

Thermal stability of amorphous LaScO3 films on silicon

Abstract: The thermal stability of amorphous LaScO3 thin films deposited by molecular-beam deposition directly on (001) Si was investigated by high-resolution transmission electron microscopy (HRTEM), transmission infrared absorption spectroscopy (IRAS), and x-ray diffraction (XRD). IRAS indicated that the as-deposited films contained <0.1A of SiO2 at the interface between LaScO3 and silicon. XRD studies showed that the films remained amorphous after annealing in N2 at 700°C, although HRTEM showed structural order on an ∼1nm length scale even in the as-deposited films. By 800°C, the LaScO3 had started to crystallize and formed a ∼5nm thick Sc-deficient interlayer between it and silicon.

Voltage Controlled GaN-on-Si HFET Power Oscillator Using Thin-Film Ferroelectric Varactor Tuning

Abstract: A 1.6 GHz power oscillator with a GaN-on-Si heterostructure field effect transistor (HFET) is reported. The voltage-controlled oscillator used a thin-film barium strontium titanate (BST) interdigital varactor as the tuning element. The surface-mount varactor was fabricated using sputtered BST film and copper metallization on alumina. An output power of 1.6 W (32 dBm) is obtained with a DC conversion efficiency of 25.5%. Flat tuning sensitivity of 500 kHz/V, 49 MHz linear frequency tuning, and power flatness of better than 0.5 dB are obtained with 0?100 V tuning voltage. The maximum oscillator phase noise is ?81.4 dBc/Hz at 100 kHz offset..

Noise characteristics of an oscillator with a barium strontium titanate (BST) varactor

Abstract: The phase noise of an oscillator with a thin-film barium strontium titanate (BST) capacitive tuning element, or varactor, is characterised and benchmarked against the same oscillator with a silicon semiconductor junction varactor. Phase noise tracks closely with varactor Q within a specific voltage range as expected. Compared to the semiconductor varactor-based oscillator, the BST-based oscillator demonstrates reduced phase noise degradation near zero volts, but greater phase noise degradation when operated near breakdown.

Manganese doped barium titanate thin film compositions, capacitors, and methods of making thereof

Abstract: The present invention is directed to a dielectric thin film composition for capacitors, the composition comprising: (1) one or more barium/titanium-containing selected from (a) barium titanate, (b) any composition that can form barium titanate during firing, and (c) mixtures thereof; dissolved in (2) organic medium; and wherein said thin film composition is doped with 0002 to 005 atom percent of a manganese-containing additive

Molecular beam epitaxy of Sm2O3, Dy2O3, and Ho2O3 on Si (111)

Abstract: We report on the epitaxial deposition of Sm2O3, Dy2O3, and Ho2O3 films on Si (111) substrates as progress towards developing a predictive model for gate oxide selection To date, films have been characterized by reflection high-energy electron diffraction, x-ray diffraction (XRD), and x-ray photoemission spectroscopy (XPS) In the case of Sm2O3, difficulty was encountered in achieving the growth of phase pure films; growth of the desired bixbyite oxide phase was accompanied by significant amounts of monoclinic oxide as detected by XRD Dy2O3 and Ho2O3 films can be produced free of unwanted phases when deposited using a background pressure of 1×10−6torr O2∕O3 and a substrate temperature between 425 and 550°C Dy2O3 films with an x-ray peak width of 06° in ω were obtained XPS studies of the Dy2O3∕Si interface are in progress, and verify the phase purity of the films

Electrical properties of lead zirconate titanate thin films with a ZrO2 buffer layer on an electroless Ni-coated Cu foil

Abstract: The effect of zirconia (ZrO2) buffer layers on the phase development and electrical properties of lead zirconate titanate (PZT, 52/48) capacitors on an electroless Ni (P)-coated Cu foil was investigated. It was demonstrated that the buffer layer can be used to engineer the final properties. The incorporation of the ZrO2 buffer layers retained acceptable capacitance densities (>350 nF/cm2 for 50 nm thick ZrO2), while significantly reducing leakage currents and improving reliability (<10−7 A/cm2 after 1 h at 25 VDC for 100 nm thick ZrO2), compared with PZT thin films directly on electroless Ni (P). The results are particularly important for embedded capacitor applications.

Synthesis of polycrystalline ytterbium monoxide thin films by molecular beam deposition

Abstract: The synthesis of ytterbium monoxide (YbO) by molecular beam deposition (MBD) is investigated for developing a lattice-matched oxide to gallium nitride. Because Yb2O3 is the thermodynamically stable oxide at atmospheric pressure, YbO has previously only been prepared by high-pressure bulk synthesis reactions. This article demonstrates that through low growth temperature and the kinetic control of molecular fluxes allowed by MBD, the polycrystalline monoxide phase can be stabilized in thin film form on silicon substrates. Once deposited, the YbO rocksalt structure is found to be stable at room temperature and atmospheric pressure. Elemental analysis indicates that films are primarily composed of Yb and O. Elemental concentrations of H, C, and N, which are known to form phases with Yb of similar structure and lattice parameter to YbO, are shown to be below the 1at.% level.

Thin film dielectrics with co-fired electrodes for capacitors and methods of making thereof

Abstract: Methods of making capacitors are disclosed that comprise forming a dielectric layer over a substrate with a first electrode or a bare metallic foil, depositing a top conductive layer over the dielectric layer, and annealing the dielectric layer and the top conductive layer wherein the foil or first electrode, the dielectric, and the conductive layer form a capacitor.

Barium Titanate Thin Films with Titanium Partially Substituted by Zirconium, Tin or Hafnium

Abstract: Disclosed are high permittivity (dielectric constant), thin film CSD barium titanate based dielectric compositions that have titanium partially substituted by zirconium, tin or hafnium. The compositions show capacitance as a function of temperature that better satisfies the X7R requirements.

Barium titanate based dielectric precursor solution comprising barium acetate for capacitor

Abstract: Disclosed are high permittivity (dielectric constant), thin film CSD barium titanate based dielectric precursor solution comprising barium acetate, a titanium source and a B site cation source The dielectrics show capacitance as a function of temperature that better satisfies the X7R requirements A method of making a capacitor with this barium titanate based dielectric precursor solution is disclosed

Barium titanate thin film comprising titanium partially substituted by zirconium, tin or hafnium

Abstract: PROBLEM TO BE SOLVED: To provide a thin film capacitor having high electrostatic capacity, low loss tangent and permissible electrostatic capacity against temperature characteristics. SOLUTION: Disclosed are high permittivity (dielectric constant), thin film CSD titanate based dielectric compositions. In the composition, titanium is partially substituted by zirconium, tin or hafnium. The composition shows electrostatic capacity as a function of temperature that better satisfies the X7R requirements. COPYRIGHT: (C)2007,JPO&INPIT