Publications by Paul Muralt | EPFL Graph Search

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ZnO and AlN, which exhibit the wurtzite structure, were deposited onto metal coated SiO2 substrates by sputtering. X-ray diffraction (XRD) indicated that the films contained no second phases and exhibited an [0001] texture. Transmission electron microscopy (TEM) observations confirmed the XRD results and revealed the columnar microstructure of the films. The width of the columnar grains were less than 30 nm for AIN and between 100 and 400 nm for ZnO. In the ZnO grains, a large concentration of defects were

Nanocomposite films consisting of BaTiO3 and CeO2 have been grown by a self-assembled approach. The composite structure of those films varied with the volume fractions of BaTiO3 and CeO2. A BaTiO3 in the form of inclined nano-fibers embedded in CeO2 matrix was obtained for CeO2-rich composition, which results in an appreciable tunability with a very low permittivity of 50. The observed tunable properties imply the competitive potential of BaTiO3-CeO2 composite as an alternative tunable material.

We report a transduction optimization method of piezo-based MEMS structures using segmentation of the excitation electrodes. Optimal transduction is achieved by matching the electric field distribution to the polarization distribution including the direct ...

AlN films are employed in RF filters for wireless communication. We report on enhanced coupling factors k(t)(2) obtained by partial substitution of Al by Sc. Al0.88Sc0.12N films were deposited by reactive magnetron sputtering from an Al0.9Sc0.1 alloy targe ...

Deposition, integration and application issues of ferroelectric thin films are briefly reviewed. Applications in ultrasonic micromotors and infra-red sensors are treated in more detail. Current results on stress measurements across the ferroelectric phase transition and on pyroelectric devices are presented.

The electro-mechanical coupling and resonance characteristics of a piezoelectric modulated thin film bulk acoustic wave resonator (PMBAR) is described quantitatively. The derived 1-D analytical model is in agreement with 2-D finite element modeling (FEM). The modeling shows that a pure shear mode excitation can be achieved and that coupling of parasitic Lamb waves is reduced in this design.

Two W protection schemes for direct-contact bottom electrodes for PZT thin films, namely RuO2/Cr and RuO2/Ru, were compared with respect to protective performance and contact resistance up to 800 degrees C annealing temperature in oxygen. Cr clearly offers better protection for W than Ru-based schemes by forming a passivating Cr2O3 layer. No Cr is detected on the RuO2 surface, even after annealing at 800 degrees C, due to its entrapment by RuO2 by oxidoreduction. However, the formation of a continuous Cr2O3

(CH3)4NHgBrI2 exhibits at room temperature a polar columnar structure based on edge-sharing anion tetrahedra with a double anion occupancy. Its orthorhombic space group is Pb2//1m. An unusual multiple phase transition sequence revealed by differential scanning calorimetry, dilatometry and permittivity vs. temperature measurements leads to a non-polar high temperature phase with a trigonal mercury coordination and the monoclinic space group P2//1/n.

An all-fiber phase modulator based on lead titanate zirconate coating deposited by dc reactive magnetron sputtering was fabricated and optically characterized. The frequency response showed a flat broadband structure up to 600 kHz, with an efficiency of 0.73 rad/(V m). This is an order of magnitude higher than that for sputtered zinc oxide based phase modulators. Radial mode resonance peaks were observed between 10 and 700 MHz, with a maximum phase modulation amplitude of 0.3 rad at the fundamental radial r

A short overview is given on deposition and integration of PZT thin films on silicon for MEMS applications. The application principles are explained and the piezoelectric coefficients are compared with the ones of AlN and ZnO. The materials figure of merits are given for various applications and discussed. The coupling coefficient for ultrasonic applications is treated in more detail.

New micromachined pressure sensors based on PZT coated silicon cantilevers have been fabricated and integrated in a photoacoustic gas detector. PZT Sol-gel thin films texture and composition were optimized with respect to the transverse piezoelectric coefficient e(31,f). A best value of -12 C/m(2) was obtained with (100)/(001) textured thin films at the MPB composition. Optimum stress compensation between the different layers composing the cantilever has been studied in order to yield flat cantilevers. A hi

Trace contaminants in sputter atmospheres (10(-2) mbar Ar) are determined with a mass spectrometer whose ionizer is directly exposed to the process pressure, whereas the quadrupole filter is kept at high vacuum. The background limitations inherent to conventional differentially pumped analyzers are overcome. Detection limits are 1 ppm for H2O and few ppb for other species.

A method for driving piezoelectric elements of a micro-system. The piezoelectric elements comprising a ferroelectric thin film, and being configured to be part of any one or a combination of items of a list comprising: a cantilever, a bridge, a diaphragm, ...

Pt-based metallizations using different adhesion layers (Ti. Zr and Ta) were studied for use as electrodes for Ferroelectric thin films on oxidized silicon substrates. Different ways of oxidizing the adhesion layers prior to ferroelectric film growth are compared. with regard to obtaining stable. adherent Pt films of well-defined (111) orientation, while avoiding lead diffusion through the electrode. Upon in-situ deposition of PbTiO3 nt high excess lead flux. lead diffusion through the Pt film was found to

A novel type of hybrid resonator based on BAW transformation into SAW in a ridged layered structure was fabricated and characterized. Bulk waves are excited by micromachined piezoelectric AlScN pillars located on the non-piezoelectric Si and sapphire subst ...

We investigated he effect of film orientation on piezoelectric and ferroelectric properties of (Bi(3.25)Ln(0.75))Ti3O12 (Ln=La, Nd, and Sm). c-axis-oriented films were grown on (111)Pt electrodes with nondoped Bi4Ti3O12 buffer layers. The films grown on (1 ...

The discovery of enhanced piezoelectricity in solid solutions of AlN and ScN is certainly one of the most important events in piezoelectric MEMS. As compared to pure AlN, it brought a crucial factor 2 to 3 improvement in a number of figures of merit govern ...

A micro-hotplate device, useful in catalytic high-temperature chemical sensors, micro-chemical reactors and as infra-red source, in particular at temperatures above 600 DEG C, comprises a thin film resistive heater (1) made of a refractory metal silicide selected from silicides of tantalum, zirconium, tungsten, molybdenum, niobium and hafnium, the silicide having a polycrystalline structure obtainalble at temperatures above 600 DEG C. The thin film resistive heater (1) is encapsulated between insulating lay

Epitaxial 50 nm and 200 nm thick films of Pb(Zr0.40Ti0.60)O-3 (PZT) have been deposited by reactive rf magnetron sputtering on conductive Nb-doped SrTiO3(100) (STO). The patterning process involved electron beam lithography of polymethylmethacrylate (PMMA), fabrication of a 75 nm thick Cr hard mask layer by means of a lift off process, and dry etching of PZT. The smallest PZT features obtained by means of this process were 50 nm in lateral dimensions. Piezoelectric sensitive scanning force microscopy in the

This paper presents the first realizations of a novel concept for thermal energy harvesting at micro scale. The devices proposed here are based on a two-step transduction combining thermo-mechanical and piezoelectric conversion. In this contribution, we pr ...

Paul Muralt

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Microstructure and defects of wurtzite structure thin films

Self-assembled ferroelectric-dielectric nanocomposite films for tunable applications

Resonant Pzt Mems Mirror With Segmented Electrodes

Electromechanical properties of Al0.9Sc0.1N thin films evaluated at 2.5 GHz film bulk acoustic resonators

Ferroelectric thin films for microsystems

Electro-mechanical coupling in shear-mode FBAR with piezoelectric modulated thin film

Conducting barrier electrodes for direct contact of PZT thin films on tungsten

(CH3)4NHgBrI2 - a New Polar Organic-Inorganic Double Halide

All-fiber phase modulator based on lead zirconate titanate thin-film coating

Piezoelectric thin films for MEMS

Piezoelectric cantilever microphone for photoacoustic GAS detector

Mass-Spectrometric Detection of Low-Ppm Contaminants in Sputter Process Systems at 10-2 Mbar, Using a Directly Exposed Ion-Source

Actuation of piezoelectric structures with ferroelectric thin films having multiple elements

Stabilized platinum electrodes for ferroelectric film deposition using Ti, Ta and Zr adhesion layers

Hybrid BAW/SAW AlN and AlScN Thin Film Resonator First Experimental data

Ferroelectric and piezoelectric properties of lanthanoid-substituted Bi4Ti3O12 thin films grown on (111)Pt and (100)IrO2 electrodes

Growth, Properties, and Applications of Al1-xScxN Thin Films

High temperature micro-hotplate

Size-effect in mesoscopic epitaxial ferroelectric structures: Increase of piezoelectric response with decreasing feature-size

Characterization of piezoelectric material for micro thermal harvesters