Electrical characterization of poly(amide-imide) for application in organic field effect devices

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Electrical characterization of lead zirconate titanate prepared by organic solution route

Two series of lead zirconate titanate (PZT) ceramics with composition Zr/Ti approximate to 53/47 have been prepared by the organic solution route. The effects on the electrical properties of calcination temperature in one series and of sintering time period in the other were examined. Dielectric constant, electrical conductivity and impedance spectroscopy results differed from one series to the other, probably due to differences in structure of the precursor powders, as seen by X-ray diffraction. Tetragonal and rhombohedral phases predominate in the powders used, respectively, in the calcined and sintered series. Physical and electrical behavior of ceramics prepared from predominantly rhombohedral powder suggests the evaporation of PbO. The presence of two semi-circles in impedance plots leads to the association of the low frequency semi-circle to the presence of PbO, which, apparently, was not eliminated from ceramics prepared from predominantly tetragonal powder. (C) 2001 Elsevier B.V. Ltd and Techna S.r.l. All rights reserved.

Structural and electrical characterization of semiconducting barium-lead-titanate ceramics

BaTiO3 is usually doped to achieve the temperature stability required by device applications, as well as to obtain a large positive temperature coefficient anomaly of resistivity (PTCR). Uniform distribution of dopants among the submicron dielectric particles is the key for optimal control of grain size and microstructure to maintain a high reliability. The system Ba0.84Pb0.16TiO3 was synthesized from high purity BaCO3, TiO2, PbO oxide powders as raw materials. Sb2O3, MnSO4 and ZnO were used as dopants and Al2O3, TiO2 and SiO2 as grain growth controllers. Phase composition was analyzed by using XRD and the microstructure was investigated by SEM. EDS attached to SEM was used to analyze phase composition specially related to abnormal grain growth. Electrical resistivities were measured as a function of temperature and the PTCR effect characterized by an abrupt increase on resistivity.

Synthesis and electrical characterization of tungsten doped Pb(Zr0.53Ti0.47)O-3 ceramics obtained from a hybrid process

Pure and W-doped PZT ceramics (PZT and PZTW) were prepared by a hybrid process consisting in the association of polymeric precursor and partial oxalate methods. The phase formation was investigated by simultaneous thermal analysis (TG/DSC) and X-ray diffraction (XRD). The effect of W doping PZT and their electrical properties was evaluated. Substitution of W by Ti leads to an increase of Curie temperature and broadening of dielectric constant. A typical hysteresis loop was observed at room temperature and the remnant polarization was increased with the content of W. (c) 2007 Elsevier B.V. All rights reserved.

Electrical characterization of SnO2 : Sb ultrathin films obtained by controlled thickness deposition

A representative study is reported on the electrical properties of SnO2: Sb. ultrathin films (thickness of 40-70 nm) produced by a deposition method based on aqueous colloidal suspensions of 3-5 nm crystalline oxides. The results revealed the films' electrical behavior in a range of 10-300 K, showing a strong dependence on dopant incorporation, with minimum resistivity values in 10 mol % of Sb content. All the samples displayed semiconductor behavior, but the transport mechanism showed a strong dependence on thickness, making it difficult to fit it to well-known models. In thicker films, the mechanism proved to be an intermediary system, with thermally activated and hopping features. Electron hopping was estimated in the range of 0.4-1.9 nm, i.e., in the same order as the particle size. (c) 2007 American Institute of Physics.

Electrical characterization of lanthanum-modified bismuth titanate thin films obtained by the polymeric precursor method

Lanthanum-modified bismuth titanate, Bi4-xLaxTi3O12 (BLT), thin films with a La concentration ranging from 0 to 0.75 were grown on Pt/Ti/SiO2/Si substrates using a polymeric precursor solution and spin-coating method. The scanning electron microscopy shows a change of morphology with increasing the lanthanum concentration. The BLT films show well-saturated polarization-electric field curves whit remnant polarizations of 14.7, 20.5, 21.5, and 20.4 muC/cm(2) for x = 0, 0.25, 0.50 and 0.75, respectively. The dielectric constant of BLT (x = 0.75 mol% La) is equal to 158 while dielectric loss remain low (tandelta = 0.0018).

Electrical characterization of in situ polymerized polyaniline thin films

The alternating conductivity, sigma*(f) = sigma'(f) + i sigma ''(f), of in situ polymerized polyaniline thin films doped with hydrochloric acid, deposited on top of an interdigitated gold line array previously deposited on glass substrates, were measured in the frequency (f) range between 0.1 Hz to 10 MHz and in the temperature range from 100 to 430 K. The results for sigma'(f) are typical of a disordered solid material: for frequencies lower than a certain hopping frequency gamma(hop), log[sigma'(f)] is frequency-independent rising almost linearly for in logf > gamma(hop). A master curve was thus obtained by plotting the real component of the conductivity using normalized scales sigma'(f)/sigma(dc) and f/gamma(hop) which is indicative of a single process operating in the whole frequency range. An expression encompassing the conduction through a disordered structure taken from previous random free energy barrier model for hopping carriers, as well a dielectric function to represent the capacitive behavior of the PAni was employed to fit the experimental results. The dielectric constant and activation energy for hopping carriers were obtained as function of the polymer doping level. (c) 2007 Elsevier B.V. All rights reserved.

Synthesis and electrical characterization of CaBi2Nb2O9 thin films deposited on Pt/Ti/SiO2/Si substrates by polymeric precursor method

We report the successful deposition of CaBi2Nb2O9 (CBN) thin films on platinum coated silicon substrates by polymeric precursor method. The CBN thin films exhibited good structural, dielectric and CBN/Pt interface characteristics. The leakage current of the capacitor structure was around 0.15 A cm(-2) at an applied electric field of 30 kV cm(-1). The capacitance-voltage measurements indicated good ferroelectric polarization switching characteristics. The typical measured small signal dielectric constant and the dissipation factor at a frequency of 100 kHz were 90 and 0.053, respectively. The remanent polarization and the drive voltage values were 4.2 C cm(-2) and 1.7 V at an applied voltage of 10 V. No significant fatigue was observed at least up to 10(8) switching cycles. (c) 2005 Elsevier B.V. All rights reserved.

Preparation, microstructural and electrical characterization of SrTiO3 thin films prepared by chemical route

Polycrystalline SrTiO3 thin films having a cubic perovskite structure were prepared at different temperatures by the polymeric precursor method on platinum-coated silicon substrate. Crystalline films with uniform composition and thickness were prepared by spin-coating and the post-deposition heat treatment was carried out at different temperatures. The film showed good structural, dielectric, and insulating properties, Scanning electron microscopy (SEM) micrographs showed no occurrence of interdiffusion between the bottom electrode (platinum) and the film during post-annealing, indicating a stable interface between the SrTiO3 and the bottom electrode. The dielectric constant and dissipation factor at a frequency of 100 kHz were 250 and 0.01, respectively, for a 360 nm thick film annealed at 600 degreesC. The capacitance versus applied voltage characteristics showed that the capacitance was almost independent of the applied voltage. The I-V characteristics were ohmic in low fields and a Schottky emission and/or Poole-Frenkel emission were postulated in high fields. Room temperature leakage current density was found to be in the order of 10(-7) A/cm(2) for a 360 nm thick film in an applied electric field of about 100 kV/cm. The charge storage density of 36 fC/mum(2) was obtained in an applied electric field of about 100 kV/cm. (C) 2001 Published by Elsevier B.V. Ltd. All rights reserved.

Electrical properties of polymer/metal interface in polymer light-emitting devices: electron injection barrier suppression

The electrical characterization of a high efficient multilayer polymer light emitting diode using poly[(2-methoxy-5-hexyloxy)-p-phenylenevinylene] as the emissive layer and an anionic fluorinated surfactant as the electron transport layer was performed. For the sake of comparison, a conventional single layer device was fabricated. The density current vs. voltage measurements revealed that the conventional device has a higher threshold voltage and lower current compared to the surfactant modified device. The effective barrier height for electron injection was suppressed. The influence of the interfaces and bulk contributions to the dc and high frequencies conductivities of the devices was also discussed. (c) 2006 Springer Science + Business Media, Inc.

Electrical properties of lanthanum doped Bi4Ti3O12 thin films annealed in different atmospheres

Pure-and lanthanun doped Bi4Ti3O12 thin films were deposited on Pt/Ti/SiO2/Si substrate using a polymeric precursor solution. Annealing in static air and oxygen atmosphere was performed at 700 degrees C for 2 h. The obtained films were characterized by X-ray diffraction and atomic force microscopy. The dielectric constant and dissipation factor were measured in the frequency region from 1 kHz to 1 MHz. Electrical characterization of the films pointed to ferroelectricity via hysteresis loop. Films annealed in static air possess a dielectric constant higher than films annealed in oxygen atmosphere due to differences in the grain size, crystallinity and structural defects. A regularly shaped hystereses loop is observed after annealing in static air. The obtained results suggest that the annealing in oxygen atmosphere can increase the trapped charge and the relaxation phenomenon. (c) 2006 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Characterization of metallic electrical contacts to SnO2 thin films lightly doped with Eu3+ ions, and photo-induced resistivity

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Electrical and Magnetic Characterization of BSCCO and YBCO HTS Tapes for Fault Current Limiter Application

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Development and characterization of biocompatible isotropic and anisotropic oil-in-water colloidal dispersions as a new delivery system for methyl dihydrojasmonate antitumor drug

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Structural, microstructural, optical and electrical properties of (Pb,Ba,Sr)TiO3 films growth on conductive LaNiO3-coated LaAO(3)(100) and Pt/Ti/SiO2/Si substrates

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)