Effect of helium implantation on the properties of plasma polymer films

Polymer films, deposited from acetylene and argon plasma mixtures, were bombarded with 150 keV He+ ions, varying the fluence, Phi, from 10(18) to 10(21) ions/m(2). Molecular structure and optical gap of the samples were investigated by infrared and ultraviolet-visible spectroscopies, respectively. Two-point probe was employed to determine the electrical resistivity while hardness was measured by nanoindentation technique. It was verified modification of the molecular structure and composition of the films. There was loss of H and increment in the concentration of unsaturated carbon bonds with Phi. Optical gap and electrical resistivity decreased while hardness increased with Phi. Interpretation of these results is proposed in terms of chain crosslinking and unsaturation. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Growth of SrBi4Ti4O15 thin films in a microwave oven by the polymeric precursor method

SrBi4Ti4O15 (SBTi) thin films were obtained by the polymeric precursor method and crystallized in a domestic microwave oven. For comparison, films were also crystallized in a conventional furnace at 700 degrees C for 2 h. Structural and morphological characterization of the SBTi thin films was investigated by X-ray diffraction (XRD) and atomic force microscopy (AFM), respectively. Using platinum coated silicon substrates configuration, ferroelectric properties of the films were determined with remanent\polarization P-r and a coercive field E-c of 5.1 mu C/cm(2) and 135 kV/cm for the film thermally treated in the microwave oven and 5.4 mu C/cm(2) and 85 kV/cm for the film thermally treated in conventional furnace, respectively. The films thermally treated in the conventional furnace exhibited excellent fatigue-free characteristics up to 10(10) switching cycles indicating that SBTi thin films can be a promise material for use in non-volatile memories. (C) 2007 Elsevier B.V. All rights reserved.

Effect of the microwave oven on structural, morphological and electrical properties of SrBi4Ti4O15 thin films grown on Pt/Ti/SiO2/Si substrates by a soft chemical method

Thin films of SrBi4Ti4O15 (SBTi), a prototype of the Bi-layered-ferroelectric oxide family, were obtained by a soft chemical method and crystallized in a domestic microwave oven. For comparison, films were also crystallized in a conventional method at 700 degrees C for 2 h. Structural and morphological characterization of the SBTi thin films were investigated by Xray diffraction (XRD) and atomic force microscopy (AFM), respectively. Using platinum coated silicon substrates, the ferroelectric properties of the films were determined. Remanent polarization P-r and a coercive field E-c values of 5.1 mu C/cm(2) and 135 kV/cm for the film thermally treated in the microwave oven and 5.4 mu C/cm(2) and 85 kv/cm for the film thermally treated in conventional furnace were found. The films thermally treated in the conventional furnace exhibited excellent fatigue-free characteristics up to 10(10) switching cycles indicating that SBTi thin films are a promising material for use in non-volatile memories. (C) 2007 Elsevier B.V. All rights reserved.

Effect of oxidizing atmosphere on the electrical properties of SrBi4Ti4O15 thin films obtained by the polymeric precursor method

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

Structure and microstructure of PbTiO3 thin films obtained from hybrid chemical method

PbTiO3 thin films were deposited on Si(100) via hybrid chemical method and crystallized between 400 and 700 degreesC to study the effect of the crystallization kinetics on structure and microstructure of these materials. X-ray diffraction (XRD) technique was used to study the structure of the crystallized films. In the temperature range investigated, the lattice strain (c/a) presented a maximum value (c/a = 1.056) for film crystallized at 600 degreesC for I h. Atomic force microscopy (AFM) was used in investigation of the microstructure of the films. The rms roughness of the films linearly increases with temperature and ranged from 1.25 to 9.04 nm while the grain sizes ranged from 130.6 to 213.6 nm. Greater grain size was observed for film crystallized at 600 degreesC for 1 h. (C) 2002 Elsevier B.V. S.A. All rights reserved.

Effects of crystallization conditions on dielectric and ferroelectric properties of PZT thin films

This paper reports studies on dielectric and ferroelectric properties of lead zirconate titanate (PZT) thin films crystallized by conventional thermal annealing (CTA) and rapid thermal annealing (RTA) in air, oxygen and nitrogen atmospheres to better understand, control and optimize these properties. The dielectric constant (epsilon) and dissipation factor (tan delta) values, at a frequency of 100 kHz; for film crystallized in air by CTA process, were 358 and 0.039, respectively. Considering the same frequency for film crystallized in air by RTA, these values were 611 and 0.026, respectively. The different dielectric values were justified by a space-charge or interfacial polarization in films, often characterized as Maxwell-Wagner type. This effect was also responsible to dispersion at frequencies above 1 MHz in film crystallized in air by CTA process and film crystallized by RTA in oxygen atmosphere. The film crystallized by RTA under nitrogen atmosphere presented an evident dispersion at frequencies around 100 Hz, characterized by an increase in both epsilon and tan delta. This dispersion was attributed to conductivity effects. The remanent polarization (P-r) and coercive field (E-c) were also obtained for all films. Films obtained from RTA in air presented higher P-r (17.8 muC cm(-2)) than film crystallized from CTA (7.8 muC cm(-2)). As a function of the crystallization atmospheres, films crystallized by RTA in air and nitrogen presented essentially the same P-r values (around 18 muC cm(-2)) but the P-r (3.9 muC cm(-2)) obtained from film crystallized under oxygen atmosphere was profoundly influenced.

DC Electric Field Dependence of the Dielectric Constant of Pzt Thin Films Prepared by Polymeric Precursor Method

This work reports dielectric measurements performed on Pb(Zr0.53Ti0.47)O3 (PZT) thin films prepared by a polymeric precursor method. The -E curves obtained for the PZT film measured at 100 kHz, under a small ac 0.2 kV/cm signal-test and a dc scan featured a typical butterfly curve. However, the -E curves obtained for PZT film under a dc scan, with a scan rate of 0.003 V/s, shows a pronounced asymmetry. The absence of a symmetric secondary peak in -E curves could be an indication of essentially 180 domain switching.

Deposition of SiOx Thin Films on Y-TZP by Reactive Magnetron Sputtering: Influence of Plasma Parameters on the Adhesion Properties Between Y-TZP and Resin Cement for Application in Dental Prosthesis

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

Incorporation of a liquid crystal to enhance the luminescence properties of Langmuir-Blodgett films of OC1OC6-PPV

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

Effects of annealing on the crystallization and roughness of PLZT thin films

Lead lanthanum zirconate titanate (PLZT) thin films with stoichiometry (9/65/35) were prepared by a dip-coating process using a polymeric organic solution. The solution viscosity was adjusted in the range of 15-56 cP. Silicon (100) substrates were previously cleaned and then immersed in the solution. The withdrawal speed of substrate from the solution was adjusted within a range of 5 to 20 mm/min. The coated substrates were thermally treated in the 450-700 degreesC temperature range. Surface roughness and crystallization of these films are strongly dependent on the annealing conditions. Infrared and X-ray diffraction data for PLZT powders heat-treated at 650 degreesC for 3 h show that the material is free of carbonate phases and crystalline. (C) 2001 Elsevier B.V. B.V. All rights reserved.

Impact of oxygen atmosphere on piezoelectric properties of CaBi2Nb2O9 thin films

CaBi2Nb2O9 (CBNO) thin films were deposited on platinum-coated silicon substrates by the polymeric precursor method, and were annealed in air and in an oxygen atmosphere. The structure, surface morphology and electrical properties of CBNO thin films have been investigated. The presence of an oxygen atmosphere during crystallization of the films affected the structure perfection and morphology, as well as ferroelectric and piezoelectric properties. A reduction in P-r and piezoelectric coefficient, an increase of V-c and displacement of the Curie point is evident in the films crystallized in an oxygen atmosphere. The impact of exposure to the oxygen atmosphere on the creation of defects caused by bismuth and oxygen vacancies between layers was also investigated by X-ray photoelectron spectroscopy. (c) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Synthesis and characterization of CaBi4Ti4O15 thin films annealed by microwave and conventional furnaces

CaBi4Ti4O15 thin films were deposited by the polymeric precursor method and crystallized in a domestic microwave oven and conventional furnace. The films obtained for microwave energy are well-adhered, homogeneous and with good specularity, when treated at 700 degrees C for 10 min. The microstructure and the structure of the films can be tuned by adjusting the crystallization conditions. When microwave oven is employed, the films presented bigger grains with mean grain size around 80 nm. For comparison, films were also prepared by the conventional furnace at 700 degrees C for 2 h. (C) 2007 Elsevier Masson SAS. All rights reserved.

Ferroelectric characteristics of SrBi4Ti4O15 thin films grown on Pt/Ti/SiO2/Si substrates by the soft chemical method

Ferroelectric SrBi4Ti4O15 thin films were successfully prepared on a Pt(111)/Ti/SiO2/Si(100) substrate for the first time by spin coating, using the polymeric precursor method. X-ray diffraction patterns of the films indicate that they are polycrystalline in nature. Atomic force microscopy (AFM) analyses showed that the surface of these films is smooth, dense and crack-free with low surface roughness (6.4 nm). At room temperature and at a frequency of 1 MHz, the dielectric constant and the dissipation factor were, respectively, 150 and 0.022. The C-V characteristics of perovskite thin film prepared at low temperature show normal ferrolectric behaviour. The remanent polarization and coercive field for the films deposited were 5.4 mu C/cm(2) and 8 5 kV/cm, respectively. All the capacitors showed good polarization fatigue characteristics at least up to 1 x 10(10) bipolar pulse cycles indicating that SrBi4Ti4O15 thin films can be a promising material for use in nonvolatile memories. (c) 2005 Elsevier B.V. All rights reserved.

Influence of oxygen flow on crystallization and morphology of LiNbO3 thin films

Polymeric precursor solution (Pechini method) was used to deposit LiNbO3 thin films by spin-coating on (100) silicon substrates. X-ray diffraction data of thin films showed that the increase of oxygen flow promotes a preferred orientation of (001) LiNbO3 planes parallel to the substrate surface. Surface roughness and grain size, observed by atomic force microscopy, change also with oxygen flow.

Influence of oxygen flow on crystallization and morphology of PLZT thin films

PLZT thin films were prepared by a dip coating process using Pechini's method, also known as polymeric precursor method. The PLZT solution was obtained from a mixture of the individual cation solutions and the process to prepare each solution is based on metallic citrate polymerization. The viscosity of the PLZT solution was adjusted at 40 cP while the ionic concentration was adjusted at 0.1 M. PLZT solutions were deposited on silicon (100) and platinum coated silicon (100) substrates with withdrawal speed at 5 mm/min. The coated substrates were thermally treated with a heating rate of 1 degreesC/min up to 300 degreesC and 5 degreesC/min up to 650 degreesC in order to obtain homogeneous and cracks free films. The influence of oxygen flow on crystallization and morphology of PLZT (9/65/35) thin film is discussed. (C) 2002 Elsevier B.V. Ltd and Techna S.r.l. All rights reserved.