Publications by Paul Muralt | EPFL Graph Search

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X-ray diffraction showed that the volume fraction of 90 degrees domains in tetragonal Pb(Zr,Ti)O-3 thin films could be substantially reduced by either hot de poling or by a bipolar pulsed-field process. In both cases, the (001) Bragg peak increased and the (100) peak decreased. However, ferroelectric hysteresis loops look quite different. Hot de poling leads to large internal herds and high frozen-in polarisation, whereas pulse treatment removes the Voltage shifts. This relaxation of the loop and x-ray diff

This paper presents a systematic approach to transduction optimization of resonant piezo-based MEMS devices. The method is based on inverse design approach using direct piezoelectric effect and exploits mechanical action of desired mode to calculate the po ...

The state of the art of thin-film pyroelectric infrared (IR) detectors is reviewed covering device physics, material performance, micro-fabrication and device examples. Emphasis is given to special issues related to thin films, such as small heat capacities and the substrate influence on the pyroelectric properties. For the latter, an overview of the hitherto reported values is given. Examples of micromachined IR detectors based on pyroelectric thin films are described. The ultimate limit of micromachined t

The domain nucleation and growth during the switching process in ferroelectric PZT thin film capacitors was observed using atomic force microscope (AFM) technique combined with a lock-in amplifier. The measured phase difference between the tip vibration signal induced by the piezoelectric displacement and the low ac modulation voltage applied to the ferroelectric capacitor was used to determine the domain polarity whereas the tip vibration amplitude was used to determine the piezoelectric coefficient. As de

The incorporation of up to 40 % lead excess into the perovskite lattice of Pb(Zr,Ti)O-3 (PZT) has been investigated. Three independent chemical composition analysis methods confirmed the correct determination of the lead excess, present as Pb2O3. High resolution TEM excludes any second phases and restricts the occurrence of lead excess to the perovskite lattice, suggesting a lead oxide perovskite of the form Pb2+Pb4+O3 with a 4-valent ion on the B-site. PZT containing such lead excess is thus a solid soluti

This paper reviews deposition, integration, and device fabrication of PbZrxTi1-xO3 (PZT) films for applications in micro-electromechanical systems. An ultrasonic micromotor is described as an example. A summary of the published data on piezoelectric properties is given. The figures of merit for various applications are discussed. Some considerations and results on operation, reliability, and depolarization of PZT thin films are presented. The state of the art allows some preliminary conclusions.

PZT thin films on insulator buffered silicon substrates with interdigitated electrodes (IDEs) have the potential to harvest more energy than parallel plate electrode (PPE) structures, because IDE structures exploit the longitudinal piezoelectric effect, wh ...

Frequency shift, design, and fabrication issues have been investigated for the realization of 8 GHz handpass filters based on AlN thin film bulk acoustic wave resonators. Fabrication includes well-textured AlN thin films on Pt (111) electrodes and SiO2/AlN ...

PZT thin films for memory applications are known to lack sufficient resistance versus polarization fatigue when used together with platinum. One possible solution for this problem is to use conductive oxides like La1-xSrxCoO3 (LSCO) as an electrode. In this paper LSCO thin films were deposited via RF magnetron sputter deposition (face to face configuration) from a single oxide target. Changing the layer beneath LSCO at 750 degrees C and an RF Power of 50 W on SiO2/Si, the film is slightly (100) textured. A.

Piezoelectric micromachined ultrasonic transducers comprising a 10 mu m thick Si device layer and a 14 pro thick piezoelectric PZT layer were investigated. The PZT films were deposited by a sol-gel technique. The transverse piezoelectric coefficient was me ...

Pb(Zr-x,Ti1-x)O-3 thin films of homogeneous composition were synthesized by means of a modified sol-gel route on Pt(111)/TiOx/SiO2/Si substrates. The usually observed gradient in B-site composition could be reduced from +/- 12 to +/- 12.5 at% amplitude in ...

We grew epitaxial SrTiO3 (STO) thin films on (001) LaAlO3 substrates via a two-step procedure using pulsed laser deposition and studied them with transmission electron microscopy in plane-view and cross-sectional samples. We found that partial misfit dislocations are the main interfacial defects, whereas planar defects are the main defects in STO films. Our results suggest that a three-dimensional island mode dominates the growth of the STO film.

The origin of a recently reported peculiar phenomenon-polarization reversal against the applied electric field in ferroelectric thin films [M. Aplanalp and P. Gunter, Ferroelectrics 258, 3 (2001), T. Morita and Y. Cho, Appl. Phys. Lett. 84, 257 (2004)]-has ...

Selective modification of zirconium alkoxide by acetic acid or acetylacetone was used in solution processing of PZT Pb(Zr,Ti)O-3 thin films by 2-methoxyethanol route. EXAFS results clearly show a decrease of Zr-O-Zr links in the acetic acid modified PZT sol implying a more homogeneous constituent metal distribution. No such decrease in comparison to unmodified sol is found in acetylacetone modified PZT. Higher level of homogeneity achieved in modified PZT sols evokes the perovskite crystallization in thin f

In situ reactively sputter deposited, 300-nm-thick Pb(Zrx,Ti1-x)O3 thin films were investigated as a function of composition, texture, and different electrodes (Pt,RuO2). X-ray diffraction analysis, ferroelectric, dielectric, and piezoelectric measurements were carried out. While for dielectric properties bulklike contributions from lattice as well as from domains are observed, domain wall contributions to piezoelectric properties are very much reduced in the morphotropic phase boundary (MPB) region. Permit

Polycrystalline aluminum nitride (AlN) layers were deposited by pulsed-dc reactive magnetron sputtering from a variable deposition angle alpha = 0 degrees-84 degrees in 5 mTorr pure N-2 at room temperature. X-ray diffraction pole figure analyses show that ...

A resonant piezoelectric scanner is developed for high-resolution laser-scanning displays. A novel actuation scheme combines the principle of mechanical amplification with lead zirconate titanate (PZT) thin-film actuation. Sinusoidal actuation with 24 V at ...

We demonstrate the implementation of a thin film pyroelectric array as a detector in an infrared gas spectrometer. The 1 x 50 element array is integrated onto a silicon chip with a sol-gel deposited zirconium modified lead titanate film (PZT) as the pyroelectrically active layer and a submicron membrane for thermal insulation. The spectrometer fitted with this detector covers a spectral range of 1.6 mu m and is capable of simultaneously detecting 15 ppm of CO2 and 200 ppm CO. Limitations of the present setu

Acoustic delay lines based on Al0.85Sc0.15N thin film hybrid transducers were investigated by finite element modeling. It was found that an acoustic impedance matching between transducer and non-piezoelectric substrate material plays a crucial role to effi ...

In this paper the simple accelerometers based on PZT thin films were developed and characterized. The functions of seismic mass and spring are given by a boss loaded cantilever structure. The strain of the cantilever is detected by a Pb(Zr,Ti)O-3 thin film. A 2 mm long and 0.8 mm wide cantilever yielded a response of 0.6 mV/g In the frequency interval between I and 600 Hz. With Delta f = 600Hz a limit of about 1mg* at 1Hz, and less above this frequency, was observed. The response predicted by the analytical

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Removal of 90 degrees domain pinning in (100) Pb(Zr0.15Ti0.85)O-3 thin films by pulsed operation

Optimization of Resonant PZT MEMS Mirrors by Inverse Design and Electrode Segmentation

Micromachined infrared detectors based on pyroelectric thin films

Observation of domain nucleation and growth during switching process

Excess lead in the perovskite lattice of PZT thin films made by in-situ reactive sputtering

PZT thin films for microsensors and actuators: Where do we stand?

Comparison of lead zirconate titanate (PZT) thin films for MEMS energy harvester with interdigitated and parallel plate electrodes

Bandpass filters for 8 GHz using solidly mounted bulk acoustic wave resonators

La1-xSrxCoO3 as electrode materials for ferroelectric thin film applications

Thick PZT sol-gel films for pMUT transducers performances improvement

Gradient free sol-gel Pb(Zr-x,Ti1-x)O-3 thin films

Growth-mode induced defects in epitaxial SrTiO3 thin films grown on single crystal LaAlO3 by a two-step PLD process

Polarization reversal due to charge injection in ferroelectric films

PZT thin films prepared from modified zirconium alkoxide

Domain and lattice contributions to dielectric and piezoelectric properties of Pb(Zr x , Ti 1− x )O 3 thin films as a function of composition

Biaxial texture development in aluminum nitride layers during off-axis sputter deposition

Resonant PZT MEMS Scanner for High-Resolution Displays

Thin film pyroelectric array as a detector for an infrared gas spectrometer

Effective SAW excitation on non-piezoelectric substrate using AlScN piezoelectric thin film BAW/SAW hybrid transducer

Fabrication and characterization of micromachined accelerometers based on PZT thin films