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15 Nov 1999

Volume 75, Issue 20, pp. 3051-3226

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Strain-imaging observation of the polarization freezing of the domains under the electrode of a Pb(Zr, Ti)O3 film

K. Takata, H. Miki, K. Torii, K. Kushida-Abdelghafar, and Y. Fujisaki

Appl. Phys. Lett. 75, 3126 (1999); http://dx.doi.org/10.1063/1.125252 (3 pages) | Cited 5 times

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Strain imaging is used to measure and image piezoelectric properties by detecting electric-field-induced strains using a scanning probe microscope. In this letter, we present ferroelectric domain imaging under an electrode in a lead-zirconate-titanate (PZT) film. The imaging has been achieved by detecting the surface force modulation caused by the electrode displacements. Observation through the electrode suppresses the effect of space charges and enables us to investigate the PZT film in the same situation in devices. We observed the freezing of polarization of a PZT film deoxidized by atomic hydrogen produced by catalysis of platinum upper electrodes due to hydrogen annealing. © 1999 American Institute of Physics.
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77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.55.-g Dielectric thin films
77.65.Ly Strain-induced piezoelectric fields
77.22.Ej Polarization and depolarization
77.80.Dj Domain structure; hysteresis
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Fully sealed, high-brightness carbon-nanotube field-emission display

W. B. Choi, D. S. Chung, J. H. Kang, H. Y. Kim, Y. W. Jin, I. T. Han, Y. H. Lee, J. E. Jung, N. S. Lee, G. S. Park, and J. M. Kim

Appl. Phys. Lett. 75, 3129 (1999); http://dx.doi.org/10.1063/1.125253 (3 pages) | Cited 644 times

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A fully sealed field-emission display 4.5 in. in size has been fabricated using single-wall carbon nanotube (CNT)-organic binders. The fabricated displays were fully scalable at low temperature, below 415 °C, and CNTs were vertically aligned using paste squeeze and surface rubbing techniques. The turn-on fields of 1 V/μm and field emission current of 1.5 mA at 3 V/μm (J = 90 μA/cm2) were observed. Brightness of 1800 cd/m2 at 3.7 V/μm was observed on the entire area of a 4.5 in. panel from the green phosphor-indium–tin–oxide glass. The fluctuation of the current was found to be about 7% over a 4.5 in. cathode area. © 1999 American Institute of Physics.
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85.45.Fd Field emission displays (FEDs)
42.79.Kr Display devices, liquid-crystal devices

Conduction and mechanical properties of atomic scale gold contacts

S. P. Jarvis, M. A. Lantz, H. Ogiso, H. Tokumoto, and U. Dürig

Appl. Phys. Lett. 75, 3132 (1999); http://dx.doi.org/10.1063/1.125254 (3 pages) | Cited 8 times

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Using a dynamic atomic force microscopy (AFM) technique in ultrahigh vacuum, we have directly measured the stiffness and conduction characteristics of a gold tip and sample. The method involves the application of a small sinusoidal oscillating force to the tip at a frequency well below the primary resonance frequency of the cantilever. By measuring the change in amplitude during the approach and retraction of the sample we have a continuous and accurate measure of the contact stiffness. The high sensitivity of this technique has enabled us to measure the mechanical properties of the junction during its initial formation. The most interesting observations are made in the region of initial contact formation where it is not possible to obtain high mechanical sensitivity from the commonly used static force measurement technique. In this region, as the contact is compressed, the contact softens continuously while the conductance remains constant prior to discrete conductance jumps. These are accompanied by simultaneous jumps in stiffness, as predicted by molecular dynamic simulations. Furthermore, the jumps show a strong tendency to half integer values of the conductance quantum. © 1999 American Institute of Physics.
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73.23.-b Electronic transport in mesoscopic systems
62.20.D- Elasticity
81.40.Jj Elasticity and anelasticity, stress-strain relations
68.35.Gy Mechanical properties; surface strains

Electrochemical formation of GaAs/Bi Schottky barriers

Philippe M. Vereecken and Peter C. Searson

Appl. Phys. Lett. 75, 3135 (1999); http://dx.doi.org/10.1063/1.125255 (3 pages) | Cited 7 times

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Bismuth layers have been deposited electrochemically on (100) n- and p-type GaAs. The electrical properties of junctions on n-GaAs were dependent on the bismuth deposition potential. Bismuth films deposited at −0.2 V (Ag/AgCl) were compact, continuous, and exhibited good adhesion; the n-GaAs/Bi junctions exhibited an average barrier height of 0.83 eV. Films deposited at ⩽−0.3 V were porous and the barrier heights exhibited an aging effect decreasing to 0.73 eV after several days under ambient conditions. Bismuth films deposited on p-GaAs exhibited barrier heights of 0.57 eV. The sum of the barrier heights for n- and p-type junctions correspond to 1.40 eV, close to the band gap of GaAs consistent with Fermi-level pinning. © 1999 American Institute of Physics.
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81.15.Pq Electrodeposition, electroplating
73.30.+y Surface double layers, Schottky barriers, and work functions
82.45.-h Electrochemistry and electrophoresis
68.35.Gy Mechanical properties; surface strains
73.40.Ns Metal-nonmetal contacts
81.40.Gh Other heat and thermomechanical treatments

Insulating GaN:Zn layers grown by hydride vapor phase epitaxy on SiC substrates

N. I. Kuznetsov, A. E. Nikolaev, A. S. Zubrilov, Yu. V. Melnik, and V. A. Dmitriev

Appl. Phys. Lett. 75, 3138 (1999); http://dx.doi.org/10.1063/1.125256 (3 pages) | Cited 23 times

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Fabrication of high-performance GaN microwave devices, which are the excellent candidates for new generation of high-power solid-state components, requires insulating GaN substrate materials. Due to lack of bulk GaN crystals and particularly lack of semi-insulating GaN substrates, we propose insulating GaN layers on silicon carbide as substrates for the fabrication of GaN-based microwave devices. In this work, we demonstrate insulating GaN layers on silicon carbide substrates. Insulating GaN layers doped with zinc were grown on silicon carbide substrates by hydride vapor phase epitaxy. High crystal quality of the grown material was proved by x-ray diffraction measurements showing the full width at a half maximum of ω-scan rocking curve of about 100 arcsec. Temperature dependence of specific resistivity of the GaN:Zn layers was measured in the temperature range from 200 to 500 K. The value of the specific resistivity was found to be 1012 Ω cm at 300 K and 109 Ω cm at 500 K. © 1999 American Institute of Physics.
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73.61.Ey III-V semiconductors
81.05.Ea III-V semiconductors
81.15.Kk Vapor phase epitaxy; growth from vapor phase

Properties of Si-doped GaN films grown using multiple AlN interlayers

D. D. Koleske, M. E. Twigg, A. E. Wickenden, R. L. Henry, R. J. Gorman, J. A. Freitas, and M. Fatemi

Appl. Phys. Lett. 75, 3141 (1999); http://dx.doi.org/10.1063/1.125257 (3 pages) | Cited 16 times

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Electrical, optical, and structural properties of Si-doped GaN films grown on multiple AlN interlayers (IL) sandwiched between high-temperature (HT) GaN are presented. We show that as the number of AlN IL/HT GaN layers increases, the electron mobility increases in the top Si-doped GaN layer, showing a near doubling from 440 to 725 cm2 V−1 s−1. Cross-sectional transmission electron microscopy images reveal a significant reduction in the screw dislocation density for GaN films grown on the AlN IL/HT GaN layers. The symmetric and off-axis x-ray linewidths increase as the number of AlN IL/HT GaN layers increase, indicating a greater relative misalignment of the adjacent HT GaN layers. Photoluminescence spectra of undoped and Si-doped GaN films on the multiple AlN IL/HT GaN layers have small yellow-band intensity. Analysis based on a single-donor/single-acceptor model for the electrical conduction suggests that the improved electron mobility is the result of a reduced acceptor concentration in the top GaN film and that this acceptor may possibly be associated with threading screw dislocations in GaN.
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73.61.Ey III-V semiconductors
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
73.50.Dn Low-field transport and mobility; piezoresistance
68.55.-a Thin film structure and morphology

Observation of harmonic current oscillations on partially oxidized Si(111) surfaces by scanning tunneling microscopy

Fangqing Xie and Peter von Blanckenhagen

Appl. Phys. Lett. 75, 3144 (1999); http://dx.doi.org/10.1063/1.125258 (3 pages) | Cited 5 times

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Harmonic oscillations of the tunneling current on partially oxidized Si(111) and on Au clusters deposited on these surfaces were observed by scanning tunneling spectroscopy (STS). The frequencies of the current oscillations are independent of the bias voltage. They are the product of a basic frequency (29.99±0.01 Hz) times an integer N. It is assumed that the basic frequency is the reciprocal of the capture time of an electron in an individual trap, that N is related to the number of traps taking part in the charge-discharge processes during STS, and that the electron traps in the small area participating in the local STS are functionally correlated by some unknown mechanism which reduces the electron capture time proportional to 1/N. © 1999 American Institute of Physics.
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72.80.Cw Elemental semiconductors
81.65.Mq Oxidation
73.25.+i Surface conductivity and carrier phenomena
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Magnitude of the threshold energy for hot electron damage in metal–oxide–semiconductor field effect transistors by hydrogen desorption

K. Hess, B. Tuttle, F. Register, and D. K. Ferry

Appl. Phys. Lett. 75, 3147 (1999); http://dx.doi.org/10.1063/1.125259 (3 pages) | Cited 14 times

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Based on the energetics for hydrogen desorption from the interface between silicon and silicon-dioxide, we argue that the hard threshold for this effect may be considerably lower than the previously assumed value (∼3.6 eV). We support these findings further by recent experimental results related to the giant isotope effect in hydrogen related transistor degradation and the fact that degradation occurs also with relatively low supply voltages. We also show that the high threshold energy model is difficult to defend at these low voltages, even though electron–electron interactions provide a mechanism to create hot electrons with energies of ∼3.6 eV. © 1999 American Institute of Physics.  
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85.30.Tv Field effect devices
73.50.Fq High-field and nonlinear effects
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics
85.30.De Semiconductor-device characterization, design, and modeling

Quantum point contact in a magnetic field: Far-infrared resonant heating observed in photoconductivity

R. J. Heron, R. A. Lewis, B. E. Kane, G. R. Facer, R. G. Clark, A. S. Dzurak, N. E. Lumpkin, R. P. Starrett, D. G. Rickel, L. N. Pfeiffer, and K. W. West

Appl. Phys. Lett. 75, 3150 (1999); http://dx.doi.org/10.1063/1.125260 (3 pages) | Cited 4 times

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We report on the far-infrared photoresponse of a quantum point contact device fabricated on a top-gated GaAs/AlGaAs heterostructure. The top-gated architecture avoids the disorder built into conventional modulation-doped structures. We observe a distinctive far-infrared magnetophotoresponse. This depends on the wavelength of the radiation and on the carrier density, which is controlled by the gate voltage. We conclude by comparison with transport data that the oscillations observed in photoconductivity and which are centred around the cyclotron energy arise from the resonant heating of electrons by the far-infrared radiation. © 1999 American Institute of Physics.
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73.50.Pz Photoconduction and photovoltaic effects
73.23.Ad Ballistic transport
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.40.Ns Metal-nonmetal contacts
73.50.Mx High-frequency effects; plasma effects
73.61.Ey III-V semiconductors

Direct gap in ordered silicon carbon alloys

Srinivasan Krishnamurthy, M. A. Berding, A. Sher, Mark van Schilfgaarde, and A.-B. Chen

Appl. Phys. Lett. 75, 3153 (1999); http://dx.doi.org/10.1063/1.125261 (3 pages) | Cited 3 times

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We show that alloying silicon with a few percent of carbon can render the band gap direct with strong optical absorption, provided the carbon atoms are ordered. The addition of carbon introduces a significant s character into the conduction band minimum, resulting in a large dipole matrix element. First-principles calculations of the optical absorption in ordered in CxSi1−x alloys for x = 1/54 and 1/32 show a near band edge absorption coefficient about half that of GaAs. © 1999 American Institute of Physics.
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71.20.Nr Semiconductor compounds
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
71.15.-m Methods of electronic structure calculations

Effective g∗ factor of two-dimensional electrons in GaN/AlGaN heterojunctions

W. Knap, E. Frayssinet, M. L. Sadowski, C. Skierbiszewski, D. Maude, V. Falko, M. Asif Khan, and M. S. Shur

Appl. Phys. Lett. 75, 3156 (1999); http://dx.doi.org/10.1063/1.125262 (3 pages) | Cited 19 times

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The conduction band parameters of two-dimensional (2D) electrons in high density GaN/AlGaN heterojunctions were studied using the cyclotron resonance and magnetotransport techniques in high magnetic fields (24 T) and low temperatures (300 mK). The Landau level splitting determined from the cyclotron resonance experiment yielded the effective mass of 2D carriers, m∗ = 0.242±0.002 m0. The Lande g factor for the 2D electrons (g = 2.06±0.04) was determined from the angular dependence of the amplitude of Shubnikov–de-Haas oscillations experiments in tilted magnetic field. © 1999 American Institute of Physics.
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73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
76.40.+b Diamagnetic and cyclotron resonances
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Thermomagnetic writing on 29 Gbit/in.2 patterned magnetic media

Chiseki Haginoya, Kazuyuki Koike, Yoshiyuki Hirayama, Jiro Yamamoto, Masayoshi Ishibashi, Osamu Kitakami, and Yutaka Shimada

Appl. Phys. Lett. 75, 3159 (1999); http://dx.doi.org/10.1063/1.125263 (3 pages) | Cited 16 times

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We have demonstrated a thermomagnetic writing on a 29 Gbit/in.2 patterned medium with perpendicular magnetic anisotropy, by using Joule heat produced by a current flowing between a magnetic dot in the medium and a magnetic force microscope tip. The possible application of this thermomagnetic method to future patterned media is also discussed. © 1999 American Institute of Physics.
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75.30.Gw Magnetic anisotropy
85.70.Li Other magnetic recording and storage devices (including tapes, disks, and drums)
75.30.Sg Magnetocaloric effect, magnetic cooling

Structural and magnetic properties of FePt:SiO2 granular thin films

C. P. Luo and D. J. Sellmyer

Appl. Phys. Lett. 75, 3162 (1999); http://dx.doi.org/10.1063/1.125264 (3 pages) | Cited 92 times

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Nanocomposite FePt:SiO2 films have been fabricated by annealing the as-deposited FePt/SiO2 multilayers at temperatures from 450 to 650 °C. These films consist of high-anisotropy tetragonal L10 FePt particles embedded in a SiO2 matrix. The structural and magnetic properties of these films were investigated. We have found that coercivity and grain size are highly dependent on the annealing temperature and SiO2 concentration. Films with coercivities in the range from 2 to 8 kOe and grain sizes of 10 nm or less were obtained. These films have considerable potential as high-density magnetic recording media. © 1999 American Institute of Physics.
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61.46.-w Structure of nanoscale materials
75.50.Kj Amorphous and quasicrystalline magnetic materials
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.50.Ss Magnetic recording materials
61.72.Cc Kinetics of defect formation and annealing
75.50.Vv High coercivity materials
75.70.Ak Magnetic properties of monolayers and thin films

High coercivity in nanostructured PrCo5-based powders produced by mechanical milling and subsequent annealing

Zhongmin Chen, X. Meng-Burany, and G. C. Hadjipanayis

Appl. Phys. Lett. 75, 3165 (1999); http://dx.doi.org/10.1063/1.125265 (3 pages) | Cited 24 times

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Nanostructured PrCo5-based PrxCo100−x (x = 15.4–20.5) powders have been synthesized by mechanical milling and subsequent annealing cast alloys. The best overall properties have been developed in stoichiometric PrCo5 powders milled for 4 h and annealed at 800 °C for 1 min with a high coercivity of 16.3 kOe along with a high Mr/Ms ratio of 0.66 and medium-strength maximum-energy product of 11.6 MGOe. The highest coercivity of 23.7 kOe has been obtained in Pr19Co81 powders. Microstructural studies reveal that a uniform PrCo5 microstructure with an average grain size of about 15 nm is developed in the powders, which have an average particle size of about 5 μm. The observed magnetic hardening is believed to arise from the high anisotropy field of the PrCo5 phase and the uniform nanoscale microstructure developed by the processing used. © 1999 American Institute of Physics.
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75.50.Ww Permanent magnets
75.50.Kj Amorphous and quasicrystalline magnetic materials
81.07.-b Nanoscale materials and structures: fabrication and characterization
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.50.Cc Other ferromagnetic metals and alloys
81.20.Wk Machining, milling
81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization
81.05.Bx Metals, semimetals, and alloys
81.20.Ev Powder processing: powder metallurgy, compaction, sintering, mechanical alloying, and granulation
75.50.Tt Fine-particle systems; nanocrystalline materials
61.46.-w Structure of nanoscale materials
61.43.Gt Powders, porous materials

The use of the in-field critical current density, Jc(0.1 T), as a better descriptor of (Bi, Pb)2Sr2Ca2Cu3Ox/Ag tape performance

L. A. Schwartzkopf, J. Jiang, X. Y. Cai, D. Apodaca, and D. C. Larbalestier

Appl. Phys. Lett. 75, 3168 (1999); http://dx.doi.org/10.1063/1.125266 (3 pages) | Cited 11 times

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Extended voltage–current characteristics of 13 optimized (Bi, Pb)2Sr2Ca2Cu3Ox/Ag multifilamentary tapes from four different manufacturers were extensively evaluated so as to extract the field-dependent Jc(H), the characteristic field Hp obtained from the relation Jc ∼ exp(−H/Hp), and the irreversibility field H∗. Values of the self-field critical current density Jc(0 T, 77 K) ranged from 12 to 63 kA/cm2, Ic(0 T,77 K) from 11 to 139 A, Hp from 128 to 204 mT, and H∗ from 163 to 369 mT, this range thus being representative of present optimized composites. Self-field can strongly dominate Jc(H) in fields below 20 mT; thus, Jc(0 T,77 K) is a flawed parameter for characterizing tapes because of its very heavy dependence on self-field. We propose that a much better descriptor of tape performance is Jc(0.1 T,77 K), because it lies outside the self-field and weak-link-destruction regimes and clearly within the flux-pinning-controlled domain where the connectivity-determined active cross-section carrying current is constant. © 1999 American Institute of Physics.
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74.72.-h Cuprate superconductors
84.71.Mn Superconducting wires, fibers, and tapes
74.25.Sv Critical currents
74.25.Ha Magnetic properties including vortex structures and related phenomena

Observation of strong to Josephson-coupled crossover in 10° YBa2Cu3Ox bicrystal junctions

R. D. Redwing, B. M. Hinaus, M. S. Rzchowski, N. F. Heinig, B. A. Davidson, and J. E. Nordman

Appl. Phys. Lett. 75, 3171 (1999); http://dx.doi.org/10.1063/1.125267 (3 pages) | Cited 16 times

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A temperature-dependent strong to weak (Josephson) coupling crossover near 75 K is observed for 10° misorientation YBa2Cu3Ox grain boundaries. Below 75 K the current–voltage characteristic (IVC) shows strongly coupled, flux-flow behavior. Above 75 K, the IVC is Josephson coupled. The data are consistent with a network of microbridges at the grain boundary defined by dislocation strain fields. The data are compared to recent calculations by A. Gurevich and A. E. Pashitskii [Phys. Rev. B 57, 13878 (1998)]. The characteristic voltages for these low-angle grain boundaries are higher than high-angle boundaries at 77 K, and could lead to improved high-temperature superconducting device operation in this temperature range. © 1999 American Institute of Physics.
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74.72.-h Cuprate superconductors
61.72.Mm Grain and twin boundaries
74.50.+r Tunneling phenomena; Josephson effects
74.25.Uv Vortex phases (includes vortex lattices, vortex liquids, and vortex glasses)
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)

Room-temperature perpendicular magnetic anisotropy in Ni/Pd (111) multilayers

Jong-Ryul Jeong and Sung-Chul Shin

Appl. Phys. Lett. 75, 3174 (1999); http://dx.doi.org/10.1063/1.125268 (3 pages) | Cited 10 times

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We report the experimental observation of room-temperature perpendicular magnetic anisotropy (PMA) in Ni/Pd (111) multilayer films having the thickness range of 5–11 Å Ni and 4–11 Å Pd sublayers, prepared by direct current magnetron sputtering on glass substrates at Ar sputtering pressure of 7 mTorr. Perpendicular magnetic anisotropy was found to be sensitively dependent on both Ni- and Pd-sublayer thicknesses, and a maximum anisotropy energy of 5.6×105 erg/cm3 was obtained for the (5 Å Ni/6 Å Pd)30 multilayer. The magnetoelastic anisotropy, quantitatively determined from in situ stress and ex situ magnetostriction coefficient measurements, was found to play an important role for the observed PMA in this system, together with the surface anisotropy. © 1999 American Institute of Physics.
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75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.30.Gw Magnetic anisotropy
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
75.80.+q Magnetomechanical effects, magnetostriction
75.70.Rf Surface magnetism

Room-temperature coercivity enhancement in mechanically alloyed antiferromagnetic-ferromagnetic powders

J. Sort, J. Nogués, X. Amils, S. Suriñach, J. S. Muñoz, and M. D. Baró

Appl. Phys. Lett. 75, 3177 (1999); http://dx.doi.org/10.1063/1.125269 (3 pages) | Cited 47 times

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The coercivity, HC, and squareness of Co powders have been enhanced at room temperature by mechanically alloying them with antiferromagnetic powders with Néel temperature, TN, above room temperature. The enhancement is maximum after field annealing above TN. The existence of loop shifts and the dependence of HC on the annealing and measuring temperatures indicate that exchange bias effects are responsible for this behavior. © 1999 American Institute of Physics.
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75.50.Tt Fine-particle systems; nanocrystalline materials
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
75.50.Ee Antiferromagnetics
75.50.Vv High coercivity materials
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
81.20.Ev Powder processing: powder metallurgy, compaction, sintering, mechanical alloying, and granulation
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Imaging of microwave permittivity, tunability, and damage recovery in (Ba, Sr)TiO3 thin films

D. E. Steinhauer, C. P. Vlahacos, F. C. Wellstood, Steven M. Anlage, C. Canedy, R. Ramesh, A. Stanishevsky, and J. Melngailis

Appl. Phys. Lett. 75, 3180 (1999); http://dx.doi.org/10.1063/1.125270 (3 pages) | Cited 47 times

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We describe the use of a near-field scanning microwave microscope to quantitatively image the dielectric permittivity and tunability of thin-film dielectric samples on a length scale of 1 μm. We demonstrate this technique with permittivity images and local hysteresis loops of a 370-nm-thick Ba0.6Sr0.4TiO3 thin film at 7.2 GHz. We also observe the role of annealing in the recovery of dielectric tunability in a damaged region of the thin film. We can measure changes in relative permittivity ϵr as small as 2 at ϵr = 500, and changes in dielectric tunability dϵr/dV as small as 0.03 V−1. © 1999 American Institute of Physics.
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77.55.-g Dielectric thin films
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.22.Ch Permittivity (dielectric function)
77.80.Dj Domain structure; hysteresis
81.40.Gh Other heat and thermomechanical treatments
81.40.Tv Optical and dielectric properties related to treatment conditions

Nanoscale investigation of domain retention in preferentially oriented PbZr0.53Ti0.47O3 thin films on Pt and on LaNiO3

J. W. Hong, W. Jo, D. C. Kim, S. M. Cho, H. J. Nam, H. M. Lee, and J. U. Bu

Appl. Phys. Lett. 75, 3183 (1999); http://dx.doi.org/10.1063/1.125271 (3 pages) | Cited 36 times

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We report results on domain retention in preferentially oriented PbZr0.53Ti0.47O3 (PZT) thin films on Pt and on LaNiO3 (LNO) electrodes. Domain images are obtained by detecting an electrostatic force exerted on the biased conductive probe. We demonstrate that polarization loss of PZT domains on LNO electrodes occurs less under no external field rather than that of PZT on Pt. The time dependence of the remnant polarization is found to follow a stretched exponential decay. © 1999 American Institute of Physics.
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77.55.-g Dielectric thin films
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.80.Dj Domain structure; hysteresis
77.22.Ej Polarization and depolarization

Realization of high tunability barium strontium titanate thin films by rf magnetron sputtering

P. Padmini, T. R. Taylor, M. J. Lefevre, A. S. Nagra, R. A. York, and J. S. Speck

Appl. Phys. Lett. 75, 3186 (1999); http://dx.doi.org/10.1063/1.125272 (3 pages) | Cited 128 times

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Ferroelectric thin films are currently being used to develop tunable microwave circuits based on the electric-field dependence of the dielectric constant. (Ba0.5Sr0.5)TiO3 (BST) films prepared by sputtering on Pt/TiO2/SiO2/Si substrates are found to exhibit a capacitance change (tunability) of nearly 4:1. Higher tunability has been attributed to the (100) texturing of the BST films and is a result of the biaxial tensile stress imposed by Si on BST making the polar axis oriented in plane. Electrical characterization shows that the dielectric permittivity increases with increase in film thickness (up to ∼200 nm). © 1999 American Institute of Physics.
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77.80.-e Ferroelectricity and antiferroelectricity
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.55.-g Dielectric thin films
77.22.Ch Permittivity (dielectric function)
81.15.Cd Deposition by sputtering

Optical and dielectric properties of quantum-confined SrBi2Ta2O9 mesocrystals

Hirotaka Higashijima, Shigemi Kohiki, Syozo Takada, Akihiko Shimizu, and Kenichi Yamada

Appl. Phys. Lett. 75, 3189 (1999); http://dx.doi.org/10.1063/1.125273 (3 pages) | Cited 5 times

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We report an increase in optical absorption peak energy from 3.9 to 5.3 eV, and a lowering of dielectric constant maximum temperature from 320 to 180 °C for SrBi2Ta2O9 mesocrystals. © 1999 American Institute of Physics.
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77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
78.66.Vs Fine-particle systems
77.22.Ch Permittivity (dielectric function)
78.40.Ha Other nonmetallic inorganics
78.30.Hv Other nonmetallic inorganics
61.43.Gt Powders, porous materials

Improved structural properties of SiO2 sol-gel films

J. González-Hernández, F. Pérez-Robles, A. Manzano-Ramírez, R. Ramírez-Bon, E. Prokhorov, Y. V. Vorobiev, and F. J. García-Rodríguez

Appl. Phys. Lett. 75, 3192 (1999); http://dx.doi.org/10.1063/1.125274 (3 pages) | Cited 2 times

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Silicon oxide films with a small amount of alpha alumina particles embedded in the glass matrix were prepared using the sol-gel method. It is found that the structural properties of these samples are superior to those observed in similarly prepared films, but without the alumina particles. This conclusion was deduced from analysis of the oxygen diffusion measurements through the SiO2 layer, using a novel method, and from the measured dielectric breakdown field. It is found that the oxygen diffusion coefficient is much lower and the dielectric breakdown field is larger in samples with the alumina particles. © 1999 American Institute of Physics.
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61.43.Fs Glasses
81.10.Dn Growth from solutions
81.10.Fq Growth from melts; zone melting and refining
81.15.Lm Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids)
77.55.-g Dielectric thin films
81.05.Kf Glasses (including metallic glasses)
77.22.Jp Dielectric breakdown and space-charge effects

Thermodynamic theory of stress distribution in epitaxial Pb(Zr, Ti)O3 thin films

H. Joon Kim, S. Hoon Oh, and Hyun M. Jang

Appl. Phys. Lett. 75, 3195 (1999); http://dx.doi.org/10.1063/1.125275 (3 pages) | Cited 32 times

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A phenomenological thermodynamic model has been developed to account for the effects of the film thickness on various properties of ferroelectric thin films. To this end, we have suitably incorporated a position-dependent stress distribution function into the elastic Gibbs function. Various physical properties can be predicted as a function of the film thickness using this modified thermodynamic formalism. A comparison of the theoretical predictions with experimental values of the average strain and the para-ferro transition temperature indicates that the tensile stress caused by the cubic-tetragonal displacive phase transition dominates over the compressive thermal stress in the epitaxially oriented tetragonal Pb(Zr, Ti)O3 thin films. © 1999 American Institute of Physics.
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68.60.Bs Mechanical and acoustical properties
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.55.-g Dielectric thin films
65.20.-w Thermal properties of liquids
65.40.gd Entropy
77.80.B- Phase transitions and Curie point
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Operation of quantum cellular automaton cells with more than two electrons

M. Girlanda, M. Governale, M. Macucci, and G. Iannaccone

Appl. Phys. Lett. 75, 3198 (1999); http://dx.doi.org/10.1063/1.125276 (3 pages) | Cited 6 times

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We present evidence that operation of quantum cellular automaton (QCA) cells with four dots is possible with an occupancy of 4N+2 electrons per cell (N being an integer). We show that interaction between cells can be described in terms of a revised formula for cell polarization, which is based only on the difference between diagonal occupancies. We validate our conjectures with full quantum simulations of QCA cells for a number of electrons varying from 2 to 6, using the configuration–interaction method. © 1999 American Institute of Physics.
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03.67.Lx Quantum computation architectures and implementations
05.45.-a Nonlinear dynamics and chaos
73.23.-b Electronic transport in mesoscopic systems
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
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