Publications by Nava Setter | EPFL Graph Search

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Pb(Mg1/3Nb2/3)O-3 (PMN) alkoxide precursor solutions were synthesized and used to prepare thin layers on TiO2/Pt/TiO2/SiO2/Si substrates by spin coating. Many parameters like homogeneity of the solution and appropriate processing must be controlled to minimize the pyrochlore formation. Optimization of the processing allowed highly (111)-oriented thin films to be obtained. Dielectric measurements and TEM investigations were performed and showed that PMN thin films exhibit relaxer behavior.

The longitudinal piezoelectric coefficient d(33) measured by the quasistatic (Berlincourt-type) method is strongly dependent on the sample aspect ratio (thickness/lateral dimension) and the type of contacts used to collect the charge and apply the pressure ...

Sol-gel process has successfully been applied for the deposition of porous PbZrxTi1-xO3 (x = 0.45, 0.15) thin films on platinized silicon wafers. Addition of a polymer as a volatile phase to the precursor sol prior to spin coating has been proved an excellent method to synthesize PZT-porous films. Introduction of pores creates a matrix void composite resulting in high figures of merit for pyroelectric applications. The dielectric constant was found to be strongly dependent to the porosity, whereas the pyroc

A dual element, point, infra-red detector is being developed from a sol-gel deposited PbTiO3 thin-film on a micro-machined silicon substrate. Patterning of the ferroelectric film and the electrodes is accomplished by photolithographic techniques. Membranes to reduce the thermal conduction from the sensor elements are created in the underlying substrate by anisotropic etching of the silicon. The measured voltage responsivity (R(V)) as a function of radiation modulation frequency is compared to theoretical pr

Using the Landau theory we demonstrate the possibility of unusual, anomalously thick ferroelectric domain walls, where the order parameter rotates with a nearly constant modulus as in ferromagnets. The effect occurs in 90 degrees charged domain walls and i ...

The crystallisation kinetics of amorphous sol-gel PZT thin films were investigated using high-temperature X-my diffraction. Crystallisation for different isotherms was monitored as a function of time. Phase transformation data were obtained from integrated X-ray peak intensities which were calibrated based on image analysis of the surface microstructure of the samples at the end of the isothermal treatments. An activation energy of 310 kJ/mol was obtained without assuming a specific kinetic model. Front the

The reduction in switchable polarization of ferroelectric thin films due to electrical stress (polarization fatigue) is a major problem in ferroelectric nonvolatile memories. There is a large body of available experimental data and a number of existing models which address this issue, however the origin of this phenomena is still not properly understood. This work synthesizes the current experimental data, models, and approaches in order to draw conclusions on the relative importance of different macro- and

The structure and electronic phenomena at the 180-degree domain wall in the rhombohedral phase of BaTiO3 are described using Landau-Ginzburg-Devonshire theory. Dependent on the wall orientation, two types of domain wall behaviors are identified. The low-en ...

The fabrication using silicon micromachining and characterization of an acoustic Lamb wave actuator is presented. The intended use of the device is for mass transport and sensor applications. The device consists of dual interdigitated transducers patterned on a thin-film composite membrane of silicon nitride, platinum, and a sol-gel-derived piezoelectric ceramic (PZT) thin film, The acoustic properties of the device are presented along with preliminary applications to mechanical transport and liquid deliver

The impact of electrical stressing on the microwave performance of the SrTiO3 films deposited onto different substrates (MgO and LaAlO3) by pulsed laser deposition has been investigated. The most important characteristics of the tunable microwave components like tunability and loss tangent have been monitored. It has been found that electrical degradation effects, being sensitive to the device operating conditions and ferroelectric film properties, are large enough to affect the performance of ferroelectric

Capacitors in metal-insulator-metal structure have been fabricated with different bottom electrodes. It has been found that the observed losses are enormous at gigahertz frequencies unless due care is taken not only for the conductivity of the bottom electrode but also its thickness. Very thin bottom electrodes (thickness similar to 100 nm) modify the dielectric response substantially and major loss contributions arise from the substrate, the electrode resistance, and the contacts. A simple approach is sugg

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) imaging is employed to characterize the surface of patterned noble metal (Pt) and titania (TiO2) thin films deposited on oxidized silicon wafers. ToF-SIMS is used to follow the different process steps during the thin films patterning as well as the post-processing cleaning. Both positive and negative ToF-SIMS modes reveal the presence of contaminants, due to the etching processes (Cl- Al-,(+)), but only on the etched surfaces. Elements due to the pos

Charge compensation at the interface is a fundamental phenomenon determining the operation conditions of thin-film devices incorporating ferroelectrics. The underlying mechanisms have been thoroughly addressed in perovskite ferroelectrics where the charge ...

The manifestations of semiconductor depletion and depolarizing effects in switching and fatigue are studied and compared. It is shown that these effects play important but quite different roles in switching. The depletion effect strongly influences the values of the coercive field, E(c), and is responsible for its film-thickness dependence. The depolarizing effect influences significantly other parameters of the hysteresis loops. It is shown that the inverse thickness dependence of E(c) can not be attribute

Pb(Zr1–xTix)O3 thin films (x = 0.55 and 0.85) were prepared on fine grained, polished ZrO2 ceramic substrates by a sol-gel method. The high thermal expansion of ZrO2 relative to Si allows the preparation of thicker PZT films with reduced thermal stress. For the x = 0.85 films, this reduction of thermal stress gives a preference of (001) over (100) oriented domains. For x = 0.55 films, square P–E hysteresis loops were obtained with: Pr = 36 µC/Cm2, and Ec = 45 kV/cm, at a field of 160 kV/cm. Pyroelectric fig

Antiferroelectrics are essential ingredients for the widely applied piezoelectric and ferroelectric materials: the most common ferroelectric, lead zirconate titanate is an alloy of the ferroelectric lead titanate and the antiferroelectric lead zirconate. A ...

The pyroelectric properties of Pb1-xCaxTiO3 (x = 0-0.3) thin films have been greatly improved by including porosity in the microstructure. Control of nucleation and growth by variation of the heating rate was used to process porous, low dielectric constant films on platinized silicon wafers. Electrical characterization of poled films showed pyroelectric coefficients of up to similar to 200 mu C/m(2) K and permitivities as low as epsilon(r) approximate to 55. The resulting high figure-of-merit p/epsilon(r) i

Properties and fabrication status of microdevices for microwaves based on polar ceramics are reviewed. We discuss bulk acoustic wave devices with AlN films, rf-MEMS capacitive switches with high permittivity materials, and tunable ferroelectrics. The relevant properties of ferroelectrics for microwave applications are summarized with emphasis on composites and thin films.

Optical properties of the PbTiO3 thin films fabricated by chemical solution deposition have been measured with variable angle spectroscopic ellipsometry in the spectral range of 1-6 eV and in the temperature interval from room temperature to 950 K. The opt ...

The large piezoelectric effect of ferroelectric ceramics is utilized in many devices for sensing and actuating purposes. In this paper, the longitudinal direct piezoelectric effect in ceramics based on lead zirconate titanate, lead titanate, barium titanate and bismuth titanate is investigated as a function of the amplitude and frequency of the external pressure, the crystal structure and microstructure of the ceramics. The domain-wall contribution to the piezoelectric response appears to be a dominant extr

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Preparation and electromechanical properties of Pb(Mg1/3Nb2/3)O-3 thin film

Analytical modeling of the apparent d(33) piezoelectric coefficient determined by the direct quasistatic method for different boundary conditions

Enhanced performance of pyroelectric microsensors through the introduction of nanoporosity

A Thin-Film Pyroelectric Detector

Anomalously thick domain walls in ferroelectrics

PZT phase formation monitored by high-temperature X-ray diffractometry

Polarization fatigue in ferroelectric films: Basic experimental findings, phenomenological scenarios, and microscopic features

Structural phase transitions and electronic phenomena at 180-degree domain walls in rhombohedral BaTiO3

Microfabricated Lamb wave device based on PZT sol-gel thin film for mechanical transport of solid particles and liquids

Investigation of electrical degradation effects in ferroelectric thin film based tunable microwave components

The effect of bottom electrode on the performance of thin film based capacitors in the gigahertz region

Imaging by time-of-flight secondary ion mass spectrometry of plasma patterned metal and oxide thin films

Polarization screening in polymer ferroelectric films: Uncommon bulk mechanism

Depletion and Depolarizing Effects in Ferroelectric Thin-Films and Their Manifestations in Switching and Fatigue

Sol-gel deposition of PZT thin films on ceramic ZrO2 substrates

The origin of antiferroelectricity in PbZrO3

High figure-of-merit porous Pb1-xCaxTiO3 thin films for pyroelectric applications

Polar ceramics in rf-MEMS and microwave reconfigurable electronics: A brief review on recent issues

The variation of PbTiO3 bandgap at ferroelectric phase transition

Instabilities in the piezoelectric properties of ferroelectric ceramics