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22 Jun 1998

Volume 72, Issue 25, pp. 3243-3383

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Effects of thermal annealing on the indium tin oxide Schottky contacts of n-GaN

J. K. Sheu, Y. K. Su, G. C. Chi, M. J. Jou, and C. M. Chang

Appl. Phys. Lett. 72, 3317 (1998); http://dx.doi.org/10.1063/1.121636 (3 pages) | Cited 69 times

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In this work indium tin oxide (ITO) films were prepared using electron beam evaporation to form Schottky contacts on n-type GaN films. The thermal stability of ITO on n-type GaN was also investigated by annealing the samples at various temperatures. In addition, current–voltage (I–V) measurements were taken to deduce the Schottky barrier heights. Owing to the large series resistance, the Norde method was used to plot the F(V)–V curves and the effective Schottky barrier heights were determined as well. The effective Schottky barrier heights were 0.68, 0.88, 0.94, and 0.95 eV for nonannealed, 400, 500, and 600 °C annealed samples, respectively. Results presented herein indicate that an increase of the barrier heights may be attributed to the formation of an interfacial layer at the ITO/GaN interface after annealing. © 1998 American Institute of Physics.
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73.30.+y Surface double layers, Schottky barriers, and work functions
73.40.Ns Metal-nonmetal contacts
61.72.Cc Kinetics of defect formation and annealing
73.61.Ey III-V semiconductors

Quantum confined Stark effect of II-VI heterostructures suitable as modulators in the blue–green spectral region

P. Michler, T. Lilienkamp, W. Ebeling, J. Gutowski, M. Behringer, M. Fehrer, and D. Hommel

Appl. Phys. Lett. 72, 3320 (1998); http://dx.doi.org/10.1063/1.121637 (3 pages) | Cited 2 times

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We present a systematic and quantitative investigation of the quantum confined Stark effect in (Zn, Cd)Se/Zn(S,Se) quantum well structures at room temperature. For this purpose, differential transmission spectroscopy is performed on two samples with different thicknesses of the active layers (4×5 nm and 10 nm) and compared to model calculations. We observe a Stark shift of 18 meV in the heavy-hole exciton peak for an electric-field change from 82 to 175 kV/cm for the 4×5 nm sample. In contrast, the 10 nm sample shows a rather weak and more Franz–Keldysh-like signal. Furthermore, we have analyzed the spectral behavior of the linewidth enhancement factor αH. Values between 5.1 and 0.2 are found at the energy of absolute maximum of the absorption change for the 4×5 nm sample. © 1998 American Institute of Physics.
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78.66.Hf II-VI semiconductors
78.20.Jq Electro-optical effects
71.35.Cc Intrinsic properties of excitons; optical absorption spectra
42.79.Hp Optical processors, correlators, and modulators

High efficiency blue–green electroluminescence and scanning tunneling microscopy studies of porous silicon

V. A. Kuznetsov, I. Andrienko, and D. Haneman

Appl. Phys. Lett. 72, 3323 (1998); http://dx.doi.org/10.1063/1.121592 (3 pages) | Cited 6 times

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Schottky barrier porous silicon diodes have been fabricated showing electroluminescence peaking at 500 nm, with an internal efficiency for blue–green emission of about 0.1%. The structures, on low-resistivity n-type silicon, operate in reverse bias. Scanning tip light emission measurements show a peak emission at 630 nm, closer to that of photoluminescence from the identical surface at 700 nm than that of the electroluminescence. The latter is concluded to arise from nonquantum effects, at the metal interface. The threshold for visible light emission is at 0.2 mA/cm2, and for infrared light is an order of 10 higher. The lifetime in air is short when unencapsulated, but longer in vacuum. © 1998 American Institute of Physics.
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78.66.Db Elemental semiconductors and insulators
78.60.Fi Electroluminescence
85.60.Jb Light-emitting devices

Photoluminescence and structural defects in erbium-implanted silicon annealed at high temperature

N. A. Sobolev, O. B. Gusev, E. I. Shek, V. I. Vdovin, T. G. Yugova, and A. M. Emel’yanov

Appl. Phys. Lett. 72, 3326 (1998); http://dx.doi.org/10.1063/1.121593 (3 pages) | Cited 17 times

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The behavior of luminescence spectra and structural defects in single crystal Czochralski silicon after erbium implantation at 1 MeV energy and 1×1013 cm−2 dose with subsequent annealing at 1100 °C for 0.25–3 h in an argon or chlorine-containing ambience was studied by photoluminescence (PL), transmission electron microscopy, and chemical etching/Nomarski microscopy. We have found that annealing in the chlorine-containing ambience gives rise to dislocation loops and pure edge dislocations with dominant dislocation-related lines in the PL spectrum. Pure edge dislocations are responsible for the appearance of the lines. The Er-related lines due to the intra-4f shell transitions in the rare-earth ions dominate in the PL spectra and no structural defects are observed after annealing in argon. The observed differences in the optical and structural properties of Si:Er are associated with intrinsic point defects generated during the implantation and annealing. © 1998 American Institute of Physics.
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78.55.Ap Elemental semiconductors
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
61.72.Cc Kinetics of defect formation and annealing
61.72.uf Ge and Si
61.72.Lk Linear defects: dislocations, disclinations
61.80.Jh Ion radiation effects

Luminescence spectra from InGaN multiquantum wells heavily doped with Si

T. Deguchi, A. Shikanai, K. Torii, T. Sota, S. Chichibu, and S. Nakamura

Appl. Phys. Lett. 72, 3329 (1998); http://dx.doi.org/10.1063/1.121594 (3 pages) | Cited 38 times

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A systematic study has been carried out on emission spectra of heavily Si-doped InGaN multiquantum wells with different degree of potential fluctuation of InGaN in the lateral plane by the use of the various excitation sources. It is demonstrated that the quantum-confined Stark effect due to the piezoelectric field plays no serious role in optical spectra under appropriate doping conditions and, then, the degree of potential fluctuation of InGaN alloys is clearly reflected in spontaneous emission spectra. © 1998 American Institute of Physics.
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78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors
78.60.Fi Electroluminescence
78.20.Jq Electro-optical effects

Laser stimulated selective area growth of quantum dots

A. Wankerl, A. T. Schremer, and J. R. Shealy

Appl. Phys. Lett. 72, 3332 (1998); http://dx.doi.org/10.1063/1.121684 (3 pages) | Cited 4 times

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We report on the selective area growth of InAs quantum dots on GaAs by ultraviolet (UV) laser stimulated organometallic vapor phase epitaxy. At the low substrate temperature of 435 °C, exposure to a 248.2 nm continuous wave laser beam enhances the InAs growth rate by approximately 30%, causing the transition from two-dimensional (2D) to 3D growth mode to occur in the laser stimulated region only. Photoluminescence spectra from the UV laser stimulated growth region show both wetting layer and quantum dot luminescence, whereas only the wetting layer peak is present in the spectra from the dark grown regions. A photoluminescence map shows good spatial agreement between the region exhibiting quantum dot luminescence and the UV stimulated spot size. Since no quantum dot peak shifts are detected, but the luminescence intensity increases towards the center of the region stimulated with the Gaussian UV beam, we conclude that the island density rather than island size distribution is influenced by the UV intensity. © 1998 American Institute of Physics.
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81.15.Kk Vapor phase epitaxy; growth from vapor phase
78.66.Fd III-V semiconductors
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
81.05.Ea III-V semiconductors
78.55.Cr III-V semiconductors
68.35.B- Structure of clean surfaces (and surface reconstruction)
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)

Effects of rapid thermal annealing on structure and luminescence of self-assembled InAs/GaAs quantum dots

S. J. Xu, X. C. Wang, S. J. Chua, C. H. Wang, W. J. Fan, J. Jiang, and X. G. Xie

Appl. Phys. Lett. 72, 3335 (1998); http://dx.doi.org/10.1063/1.121595 (3 pages) | Cited 96 times

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Postgrowth rapid thermal annealing was used to modify the structural and optical properties of the self-assembled InAs quantum dots grown on GaAs substrates by molecular beam epitaxy. It is found that significant narrowing of the luminescence linewidth (from 78.9 to 20.5 meV) from the InAs dot layer occurs together with about 260 meV blueshift at annealing temperatures up to 850 °C. Observation of high-resolution transmission electron microscopy shows the existence of the dots under lower annealing temperatures but disappearance of the dots annealed at 850 °C. The excited-state-filling experiments for the samples show that the luminescence of the samples annealed at 850 °C exhibits quantum well-like behavior. Comparing with the reference quantum well, we demonstrate significant enhancement of the interdiffusion in the dot layer. © 1998 American Institute of Physics.
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
78.66.Fd III-V semiconductors
61.72.Cc Kinetics of defect formation and annealing
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
78.55.Cr III-V semiconductors
68.35.Fx Diffusion; interface formation

Characterization of substrate/thin-film interfaces with x-ray microdiffraction

I. C. Noyan, J. Jordan-Sweet, E. G. Liniger, and S. K. Kaldor

Appl. Phys. Lett. 72, 3338 (1998); http://dx.doi.org/10.1063/1.121596 (3 pages) | Cited 22 times

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The (buried) interface between a polycrystalline Al thin-film feature and its substrate (single crystal Si) was characterized with x-ray microdiffraction. Using a focused x-ray beam (effective spot size on the specimen ∼2×12 μm) with the Si 004 reflection, topographic images of the Si around and under the metallization feature were constructed. Comparison with shear-lag model calculations indicate that the interface is not fully coupled despite the absence of surface cracks. © 1998 American Institute of Physics.
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68.35.Ct Interface structure and roughness
61.05.C- X-ray diffraction and scattering

Composition modulation in InxGa1−xAs nanocrystals embedded in SiO2 film by radio frequency magnetron cosputtering

Jianzhong Shi, Kaigui Zhu, and Lide Zhang

Appl. Phys. Lett. 72, 3341 (1998); http://dx.doi.org/10.1063/1.121597 (3 pages) | Cited 4 times

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We have succeeded in preparing InxGa1−xAs (0.2 ⩽ x ⩽ 0.8) nanocrystals with 3–5 nm in size embedded in SiO2 thin film by using the radio frequency magnetron cosputtering technique. The analyses of x-ray diffraction and Raman spectra strongly suggest the existence of InxGa1−xAs nanocrystals in the matrices. It has been found that the optical absorption edge, lattice constant and Raman shift can be modulated by composition of InxGa1−xAs by varying the effectively sputtered area ratio of InAs to GaAs on the target. The blueshift of the optical absorption edge is explained by the effective mass approximation method. © 1998 American Institute of Physics.
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81.15.Cd Deposition by sputtering
68.55.Nq Composition and phase identification
81.05.Ea III-V semiconductors
81.07.-b Nanoscale materials and structures: fabrication and characterization
78.30.Fs III-V and II-VI semiconductors
78.66.Fd III-V semiconductors
61.66.Fn Inorganic compounds

Annealing effects on carbon-induced germanium dots in silicon

S. Schieker, O. G. Schmidt, K. Eberl, N. Y. Jin-Phillipp, and F. Phillipp

Appl. Phys. Lett. 72, 3344 (1998); http://dx.doi.org/10.1063/1.121598 (3 pages) | Cited 18 times

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The growth of 2.4 monolayers Ge on 0.2 monolayers of predeposited C on Si results in the formation of 15 nm size Ge islands. Fifty stacked layers of these C-induced Ge dots are grown on Si (001) at 460 °C. Different pieces of the wafer are annealed at temperatures between 460 and 950 °C and for times ranging from 1 to 20 min at 850 °C. For temperatures higher than 550 °C, a pronounced energy blueshift and an evolution from one broad photoluminescence peak to two well-resolved lines reflect a gradual transition from quantum dot states to quantum well-like states. As transmission electron microscopy images illustrate, diffusion processes completely smear out the sharp interfaces between the dots and the surrounding Si. An activation energy of only 1.6 eV and temperature-dependent diffusion coefficients are derived from simple model calculations. © 1998 American Institute of Physics.
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
81.05.Cy Elemental semiconductors
61.72.Cc Kinetics of defect formation and annealing
78.66.Db Elemental semiconductors and insulators
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
78.55.Ap Elemental semiconductors
68.35.Fx Diffusion; interface formation

Structure and composition of the c(4×4) reconstruction formed during gallium arsenide metalorganic vapor-phase epitaxy

B.-K. Han, L. Li, Q. Fu, and R. F. Hicks

Appl. Phys. Lett. 72, 3347 (1998); http://dx.doi.org/10.1063/1.121599 (3 pages) | Cited 13 times

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Surfaces of GaAs (001) were prepared by metalorganic vapor-phase epitaxy and characterized by scanning tunneling microscopy, x-ray photoelectron spectroscopy, infrared spectroscopy, and low-energy electron diffraction. Upon removal from the reactor, the gallium arsenide surface exhibits a (1×2) reconstruction, which is a disordered variant of the c(4×4). The disorder arises from the presence of adsorbed alkyl groups. Heating the sample to 350 °C desorbs the hydrocarbons and produces a well-ordered c(4×4) structure. A model is proposed for the alkyl-terminated (1×2) reconstruction. © 1998 American Institute of Physics.
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68.55.-a Thin film structure and morphology
81.15.Kk Vapor phase epitaxy; growth from vapor phase
68.55.Nq Composition and phase identification
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.35.Rh Phase transitions and critical phenomena
81.05.Ea III-V semiconductors
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics
78.30.Fs III-V and II-VI semiconductors
78.66.Fd III-V semiconductors
79.60.Bm Clean metal, semiconductor, and insulator surfaces

The effect of offset charge deposited directly onto single-electron devices

M. R. Graham and H. Ahmed

Appl. Phys. Lett. 72, 3350 (1998); http://dx.doi.org/10.1063/1.121600 (3 pages) | Cited 1 time

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The effects of charge deposited directly in the vicinity of a multiple tunnel junction single-electron transistor have been investigated. Two regimes of offset effects have been observed with a continuous transition between them. The deposited charge causes the device current to oscillate in a manner analogous to sweeping the gate voltage, and an equivalence between the two phenomena has been demonstrated. In addition, ions landing very close to the device cause a discontinuous change in the device current such that the arrival of individual ions can be time resolved. © 1998 American Institute of Physics.
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85.35.Gv Single electron devices

Structural and electronic properties of low dielectric constant fluorinated amorphous carbon films

Yanjun Ma, Hongning Yang, J. Guo, C. Sathe, A. Agui, and J. Nordgren

Appl. Phys. Lett. 72, 3353 (1998); http://dx.doi.org/10.1063/1.121601 (3 pages) | Cited 43 times

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Fluorinated amorphous carbon (a-CFx) films were studied by high-resolution x-ray absorption, emission, and photoelectron spectroscopy. The composition and local bonding information were obtained and correlated with substrate temperature during deposition. The data suggest that the structure of the a-CFx is mostly of carbon rings connected by CF2 groups. The cross linking increases with substrate temperature. © 1998 American Institute of Physics.
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68.55.Nq Composition and phase identification
77.55.-g Dielectric thin films
61.43.Er Other amorphous solids
73.61.Ng Insulators
77.84.-s Dielectric, piezoelectric, ferroelectric, and antiferroelectric materials
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
78.70.Dm X-ray absorption spectra
78.70.En X-ray emission spectra and fluorescence
79.60.Ht Disordered structures
79.60.Dp Adsorbed layers and thin films
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

Thin film electroluminescence in highly anisotropic oxide materials

T. Xiao, A. H. Kitai, G. Liu, A. Nakua, and J. Barbier

Appl. Phys. Lett. 72, 3356 (1998); http://dx.doi.org/10.1063/1.121602 (3 pages) | Cited 27 times

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A criterion for high performance electroluminescent (EL) phosphor based on the crystal structure of the phosphor host has been developed. The performance of some best-performing EL oxide phosphors is correlated to the fundamental atomic arrangements of the phosphor host and to the microstructural characteristics of their thin films. It is shown that, contrary to popular beliefs, oxide phosphors with certain crystallographic features do have the capability of transporting significant current densities of hot electrons. Examples of newly developed high brightness and efficiency oxide EL phosphors are presented. © 1998 American Institute of Physics.
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78.66.Nk Insulators
78.60.Fi Electroluminescence
68.55.-a Thin film structure and morphology
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High-resolution x-ray spectra measured using tantalum superconducting tunnel junctions

P. Verhoeve, N. Rando, A. Peacock, A. van Dordrecht, B. G. Taylor, and D. J. Goldie

Appl. Phys. Lett. 72, 3359 (1998); http://dx.doi.org/10.1063/1.121603 (3 pages) | Cited 18 times

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The spectral response of a 100×100 μm2 tantalum based superconducting tunnel junction to 5.9 keV x-ray photons from a 55Fe source has been studied. In full illumination the energy resolution for the Mn Kα line complex is 56 eV, dominated by spatial nonuniformity in the response of the detector. When illuminating selectively a 5–10 μm diam spot in the center of the detector, the energy resolution improves to 22 eV, corresponding to 15.7 eV for the individual Mn Kα1 and Mn Kα2 lines. This exceeds the predicted theoretical energy resolution of 7.3 eV for this type of device by only a factor of ∼2. © 1998 American Institute of Physics.
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85.25.Qc Superconducting surface acoustic wave devices and other superconducting devices
07.85.Fv X- and γ-ray sources, mirrors, gratings, and detectors

Field-free core, current distribution, and alternating current losses in self fields for rectangular superconductor tapes

T. Fukunaga, R. Inada, and A. Oota

Appl. Phys. Lett. 72, 3362 (1998); http://dx.doi.org/10.1063/1.121604 (3 pages) | Cited 16 times

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A method is proposed to calculate the shape of field-free core, the current distribution, and accordingly the alternating current (ac) losses in self fields as a parameter of current amplitude I0 for straight superconductor tapes with the arbitrary sectional geometry. The validity for this is justified by showing that magnetic fields inside the field-free core are negligibly small and by checking that calculation results of ac losses for elliptic tapes agree with the prediction by the theory of Norris. The ac losses for rectangular tapes behave as a thin strip superconductor in high I0 values near critical current, while showing a gradual deviation from this behavior as I0 is lowered. A decrease in the aspect ratio of width to thickness in the rectangular tape makes the deviation more remarkable. © 1998 American Institute of Physics.
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84.71.Mn Superconducting wires, fibers, and tapes
74.25.Sv Critical currents
74.20.-z Theories and models of superconducting state

Nondestructive investigation of microstructures and defects at a SrTiO3 bicrystal boundary

Q. D. Jiang, Z. J. Huang, A. Brazdeikis, M. Dezaneti, C. L. Chen, P. Jin, and C. W. Chu

Appl. Phys. Lett. 72, 3365 (1998); http://dx.doi.org/10.1063/1.121605 (3 pages) | Cited 5 times

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The effects of thermal annealing on the microstructure at the grain boundary of a 36.8° symmetric [100] tilt SrTiO3 bicrystal were studied. Scanning tunneling microscopy and atomic force microscopy were used for nondestructive observation of the boundary structures. Annealing the bicrystalline substrates at temperatures as low as 780 °C led to the formation of grooves at their boundaries. This provides direct evidence that the thickness depression of YBa2Cu3O7−δ films at the bicrystal boundaries originates from the underlying grooved substrates. Defects characterized as holes with diameters ranging from ∼ 30 nm to ∼ 200 nm were also observed. © 1998 American Institute of Physics.
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68.35.Ct Interface structure and roughness
61.72.Mm Grain and twin boundaries
61.72.Cc Kinetics of defect formation and annealing
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Negative magnetoresistance in GaAs with magnetic MnAs nanoclusters

H. Akinaga, J. De Boeck, G. Borghs, S. Miyanishi, A. Asamitsu, W. Van Roy, Y. Tomioka, and L. H. Kuo

Appl. Phys. Lett. 72, 3368 (1998); http://dx.doi.org/10.1063/1.121606 (3 pages) | Cited 52 times

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We show a negative magnetoresistance (MR) in GaAs with magnetic MnAs nanoclusters (about 1.5% at 30 K in 1 T). The clusters were formed in a two step process consisting of the molecular beam epitaxy of (Ga,Mn)As layer and the subsequent annealing. The origin of the negative MR is attributed to the presence of the MnAs clusters. The mechanism is considered to be a spin-dependent scattering of carriers by MnAs clusters which decreases when the direction of the magnetization between the clusters aligns with the magnetic field. © 1998 American Institute of Physics.
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73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
73.63.-b Electronic transport in nanoscale materials and structures
75.50.Tt Fine-particle systems; nanocrystalline materials
75.50.Kj Amorphous and quasicrystalline magnetic materials
75.50.Dd Nonmetallic ferromagnetic materials
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects

Concurrent variation of giant magnetoresistance and saturation Kerr rotation in NiCo/Cu multilayers

J. Du, L. N. Tong, M. Lu, K. Xia, M. H. Pan, J. Wu, D. Feng, H. R. Zhai, L. Y. Chen, X. F. Jin, and H. Xia

Appl. Phys. Lett. 72, 3371 (1998); http://dx.doi.org/10.1063/1.121607 (3 pages) | Cited 1 time

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The dependences of magneto-optical effect, effective optical constants, and giant magnetoresistance (GMR) on the thickness of Cu layers were investigated in NiCo/Cu multilayers prepared by rf magnetron sputtering. A peak of saturation polar Kerr rotation θK, occurred simultaneously with that of GMR ratio when the Cu thickness is around 1.0 nm, where a clear drop of the effective optical constants n and k appeared. The peak of θK is mainly caused by the reduction of the effective optical constants, which dominate over the small drop of the effective off-diagonal elements of the dielectric tensor. The concurrent variation of GMR and θK is related to antiferromagnetic interlayer coupling, which may change the electron band structure and thus the optical and magneto-optical transitions of electrons. © 1998 American Institute of Physics.
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75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
78.20.Ls Magneto-optical effects
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
72.15.Gd Galvanomagnetic and other magnetotransport effects
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
75.47.De Giant magnetoresistance
73.61.At Metal and metallic alloys
75.50.Ee Antiferromagnetics
78.66.Bz Metals and metallic alloys
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Electromechanical properties of sol-gel derived Ca-modified PbTiO3 films

A. Kholkin, A. Seifert, and N. Setter

Appl. Phys. Lett. 72, 3374 (1998); http://dx.doi.org/10.1063/1.121608 (3 pages) | Cited 27 times

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Piezoelectric coefficients and electric field-induced strains are investigated in Ca-modified PbTiO3 (PCT) films deposited by sol-gel technique. The microstructural evolution and related electromechanical properties are studied as a function of Ca content and porosity of the films. The porosity is tailored by changing the heating rate during the final crystallization anneal. It is found that piezoelectric properties of porous films heated at slow rates are superior to those of dense films crystallized using higher heating rates. This is explained as a result of the constraining effect of the substrate, which apparently reduces the piezoelectric and strain responses in dense films. Electromechanical properties are also improved with Ca addition due to the decrease of tetragonality and ease of 90° domain rotation. Charge piezoelectric coefficients in porous films are close to those of PCT ceramics of the same composition. These results, combined with the low dielectric constant, make PCT films an attractive material for microelectromechanical applications. © 1998 American Institute of Physics.
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77.55.-g Dielectric thin films
77.65.Bn Piezoelectric and electrostrictive constants
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.22.Ch Permittivity (dielectric function)
61.72.Cc Kinetics of defect formation and annealing
81.15.Lm Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids)

Asymmetric electro-optical switching of a nematic cell controlled by a corona poled ferroelectric polymer layer

L. M. Blinov, S. P. Palto, S. V. Yakovlev, and D. G. Sikharulidze

Appl. Phys. Lett. 72, 3377 (1998); http://dx.doi.org/10.1063/1.121609 (3 pages) | Cited 13 times

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A polar asymmetry of electro-optical behavior has been studied for a liquid-crystal cell, one electrode of which is covered by a thin film of a ferroelectric polymer. A well-known copolymer PVF2–TrFE (70:30) previously poled by a corona discharge has been used to modify the quadratic electro-optical response of the nematic mixture in a hybrid cell. The voltage for the onset of switching becomes polarity dependent. A simple model of an internal electric field created by a poled ferroelectric and built in the nematic layer is discussed, which is consistent with the sign and general features of the effect. © 1998 American Institute of Physics.
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42.79.Kr Display devices, liquid-crystal devices
42.79.Ta Optical computers, logic elements, interconnects, switches; neural networks
77.55.-g Dielectric thin films
77.80.-e Ferroelectricity and antiferroelectricity
77.84.Jd Polymers; organic compounds
77.84.Nh Liquids, emulsions, and suspensions; liquid crystals

Built-in voltages and asymmetric polarization switching in Pb(Zr,Ti)O3 thin film capacitors

J. Lee, C. H. Choi, B. H. Park, T. W. Noh, and J. K. Lee

Appl. Phys. Lett. 72, 3380 (1998); http://dx.doi.org/10.1063/1.121610 (3 pages) | Cited 47 times

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Asymmetric polarization switching of Pb(Zr,Ti)O3 (PZT) thin films with different electrode configuration has been studied in (La,Sr)CoO3/Pb(Zr,Ti)O3/(La,Sr)CoO3 (LSCO) heterostructures in which the conducting oxide (La,Sr)CoO3 and/or LaCoO3 (LCO) have been used as an electrode. Polarization-voltage (P-V) hysteresis loop of LSCO/PZT/LSCO was symmetric. However, LCO/PZT/LSCO showed a largely asymmetric P-V hysteresis loop and large relaxation of the remanent polarization at the negatively poled state, eventually leading to an imprint failure. On the other hand, LSCO/PZT/LCO exhibited large relaxation of the positively poled state. The asymmetric behavior of the polarized states implies the presence of an internal electric field inside the PZT layer. It is suggested that the internal electric field is caused by built-in voltages at LCO/PZT and LSCO/PZT interfaces. The built-in voltages at LCO/PZT and LSCO/PZT interfaces were 0.6 V and 0.12 V, respectively. © 1998 American Institute of Physics.
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84.32.Tt Capacitors
85.50.-n Dielectric, ferroelectric, and piezoelectric devices
77.80.Fm Switching phenomena
77.22.Ej Polarization and depolarization
77.22.Gm Dielectric loss and relaxation
77.80.Dj Domain structure; hysteresis
77.55.-g Dielectric thin films
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
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FREE

Erratum: “X-ray photoelectron spectrscopy studies on Pd-doped SnO2 liquid petroleum gas sensor” [Appl. Phys. Lett. 71, 2358 (1997)]

A. R. Phani

Appl. Phys. Lett. 72, 3383 (1998); http://dx.doi.org/10.1063/1.121611 (1 page)

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Abstract Unavailable
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07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
79.60.Bm Clean metal, semiconductor, and insulator surfaces
99.10.Cd Errata
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