Publications by Paul Muralt | EPFL Graph Search

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Growth of (111)-oriented Pb(Zr,Ti)O-3 has been achieved on a RuO2 film which was (100) textured. This texture could be obtained by using a (111)-textured Pt film as a template. The whole layer stack was grown on an amorphous SiO2 layer, that is a thermal oxide of a silicon wafer. A good (111)-orientation of the Pt template layer is thus the starting point of oriented growth. XRD and TEM studies have been carried out to find the orientation relationship between Pt(111), RuO2(100) and PZT(111). (C) 1999 Elsev

Lead zirconium titanium oxide (PZT) thin films are used for their ferroelectric and piezoelectric properties. The composition of the PZT is very important for these properties, and may also be influenced by inter- diffusion with the bottom electrode, on which the PZT film has been grown at rather elevated temperature (550°C-600°C). The bottom electrode is essentially made of RuO2 deposited on a chromium adhesion layer which also helps to block oxygen diffusion. A part of the multi-layer device is shown in F

We report on the optimization of a multilayer platinum/aluminum nitride (AlN) stack with an AlN active layer thickness of 50 nm for piezoelectric actuation in nanoelectromechanical systems (NEMS). Experiments in reactive sputtering of AlN were used to find optimal parameters for good crystallinity and low residual stress of a four layer film stack, shown in Figure 1. A direct relationship was measured between the AlN seed layer thickness and the x-ray diffraction (XRD) rocking curve’s full width at half max

PbZrxT1-x O3 (PZT) films on silicon substrates can be used for various micro mechanical devices. An insitu reactive sputter deposition process at 600°C has been developed for this application. Three magnetron sources with metal targets have been applied simultaneously. Within a certain process window, the [Pb] / ([Zr]+[Ti]) ratio in the film is self stabilized at stoichiometry by desorption of the excess Pb. Films of up to 1 micron thickness have been fabricated. For the composition x = 0.4 the films exhiba

Piezoelectric micromachined ultrasonic transducers for airborne and immersed applications working in the frequency range from 20 kHz in liquid to 750 kHz in air have been fabricated and characterized, as well as simulated by finite element modelling. The basic element consisted of a oxidized and platinized silicon membrane coated with a 2 mum thick (100)-textured Pb(Zr,Ti)O-3 (PZT) thin film deposited by sol-gel techniques. SOI wafers have been applied to obtain a good definition of the silicon part of the

Due to their high specific energy and energy density, micro-solid oxide fuel cells1,2 (µ-SOFCs) are seen as one of the technologies that could help satisfying the continuously increasing demand for electric energy in portable electronic devices. The µ-SOFC is a less than 1 µm thin free-standing membrane. The membrane consists of ceramic and metallic thin film layers integrated on a micro-structurable substrate based on MEMS technologies. In this study, Foturan® glass ceramic and silicon µ-SOFCs substrates a

In this paper we report work on a modified potassium sodium niobate composition that has the potential to replace PZT for piezoelectric thin film applications. Pulsed laser depositions were undertaken on platinised Si substrates. The resultant films were found to be well-oriented in the [100] direction and almost phase-pure. TEM analysis of film cross-sections revealed the grain structure to be highly columnar. Values for P-s = 3.8 mu C/cm(2) and E-c = 20 kV/cm were derived from polarisation hysteresis meas

The in-situ reactive sputter deposition of PbTiO3 on Pt/Ti/SiO2/Si from two metallic targets was investigated. A minimal lead oxide flux of two to three times the titanium oxide flux is needed in order to obtain stoichiometric films with the perovskite structure. For higher fluxes, the Pb/Ti ratio in the film stays at the stoichiometric value 1; the orientation changes from random to ; and the film morphology transforms from a rough to a smooth polycrystalline film. The obtained dielectric constants va

For micromechanical applications, piezoelectric PbZrTO3 (PZT) thin films have been deposited on metallised Si3N4/SiO2 layers on Si wafers. Films with compositions near the morphotropic phase boundary (x=0.53) were prepared at 600°C using a multitarget, in- ...

A micro power generator harvesting vibration energy by resonant inertial oscillation of a piezoelectric laminated cantilever with proof mass was designed, fabricated, and characterized. The active part with 2 pm thick PZT on 5 mu m silicon was equipped wit ...

Combinatorial high-vacuum chemical vapor deposition (HV-CVD) was used to identify the conditions required to obtain hafnium-doped lithium niobate thin films on sapphire {001} substrates. Niobium tetraethoxydimethylaminoethoxide (Nb(OEt)(4)(dmae)), lithium tert-butoxide (Li(OBut)), and hafnium tert-butoxide (Hf(OBut)(4)) were used as precursors. X-ray diffraction (XRD) and transmission electron microscopy (TEM) indicated that a single phase of textured {001} Hf-doped lithium niobate film was obtained under c

The properties of Pb1-xCaxTiO3 (x=0-30) thin films for applications in point-detectors and arrays can be further improved ii porous, low-dielectric constant layers are being Used. Both 2-methoxyethanol and 1,3-propanediol based solution precursors were used for spin-coating platinized Si3N4/SiO2/Si wafers. The heating-rate during the final anneal was observed to be the controlling parameter for the evolution of either dense or porous microstructures, Low temperature crystallization of the perovskite phase (

A measurement setup for the detailed study of the transverse piezoelectric coefficient e(31,f) in the converse (actuator) mode was developed. It allows the assessment of the piezoelectric stress in thin films on silicon cantilevers and provides for a corre ...

Triple layer SiO2/AlN/SiO2 composite thin film bulk acoustic wave resonators (TFBARs) were studied for applications in atomic clocks. The TFBAR's were tuned to 3.4 GHz, corresponding to half the hyperfine splitting of the ground state of rubidium Rb-87 atoms. The quality factor (Q) was equal to 2300 and the temperature coefficient of the resonance frequency f(r) amounted to 1.5 ppm/K. A figure of merit Qf(r) of similar to 0.8 x 10(13) Hz and a thickness mode coupling factor of 1% were reached. Such figures

There is a need for chemically resistant coatings that protect the exposed surface of microfluidics components. Pinhole free films with low stress and a good uniformity on flat and inclined surfaces are required. In this study, amorphous silicon carbide (SiC) thin films have been deposited by RF magnetron sputtering on hat surfaces and into micromachined cavities of Si (100). The variation of RF power, deposition pressure and substrate bias voltage have been studied. Depending on the deposition conditions,

Bimorph structures are a standard method for transforming the high force of piezoelectric materials into a large deflection. In micro electromechanical systems (MEMS) applications, it is preferable to use structures consisting of a passive substrate (usual ...

Pyroelectric thin film 12-element linear arrays (element size 0.4x0.9 mm(2)) have been fabricated by standard photolithography techniques on silicon substrates. A voltage responsivity of almost 800 V/W in air and 3000 V/W in vacuum is measured at low frequencies (0.1-1 Hz). Measurements are compared to finite element simulations. Doping of lead titanate thin films have been studied. Incorporation of porosity and Ca-doping of lead titanate thin films was found to improve significantly the pyroelectric proper

The piezoelectric properties of lead zirconate titanate (PZT) thin ﬁlms deposited on thick silicon substrates and thin silicon membranes were investigated using optical interferometry. The effect of the geometrical constraints and clamping effects on the piezoelectric response is discussed. The study of the dielectric permittivity and the loss as a function of the amplitude of the alternating electric field reveals that extrinsic contributions to the dielectric permittivity become active at large fields. Th

Poling of calcium and zirconium modified lead titanate pyroelelectric thin films has been studied, Poling temperature and electrical field were optimized to achieve high figure of merits. It was found that thermal activation is important to obtain highly poled films. Defect-dipole complexes are supposed to play a major role to retain the polarization and also to enhance it. Porous calcium substituted films achieved an up to three times higher voltage response than zirconate substituted thin films, because p

The effective piezoelectric transverse coefficient e(31,f) was measured on various lead zirconate-titanate (PZT) and aluminum nitride thin films. The measurement set-up is based on the collection of the electric charges created by the forced deflection of a Si cantilever coated with a piezoelectric material. The maximum value was obtained from a tetragonal composition of PZT (45/55 Zr/Ti ratio) and was equal to 8.3 C/m(2). The ALN layer exhibited 97% of the theoretical value calculated from single crystal d

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Growth of (111)-oriented PZT on RuO2(100)/Pt(111) electrodes by in-situ sputtering

Chemical analysis of lead zirconium titanium oxide films

50 nm thick AlN Films for Actuation and Detection of Nanoscale Resonators

Thin piezoelectric films for micro-electromechanical components

Simulation and characterization of piezoelectric micromachined ultrasonic transducers (PMUT's) based on PZT/SOI membranes

Microfabrication of free-standing micro-solid oxide fuel cells on Foturan® and silicon substrates

Pulsed laser deposition of KNN-based ferroelectric thin films on platinised Si substrates

In-Situ Thin Film Growth of PbTiO3 By Multi Target Sputtering

Pb(Zr,Ti)O3 thin films by in-situ reactive sputtering on micromachined membranes for micromechanical applications

Vibration Energy Harvesting with PZT Micro Device

Combinatorial High-Vacuum Chemical Vapor Deposition of Textured Hafnium-Doped Lithium Niobate Thin Films on Sapphire

Electrical properties and microstructural evolution of porous Pb1-xCaxTiO3 pyroelectric thin films

Characterization and Fatigue of the Converse Piezoelectric Effect in PZT Films for MEMS Applications

3.4 GHz composite thin film bulk acoustic wave resonator for miniaturized atomic clocks

Sputtered silicon carbide thin films as protective coating for MEMS applications

Admittance Matrix of a Trapezoidal Piezoelectric Heterogeneous Bimorph

Thin film pyroelectric arrays as infra-red detectors

Properties of Piezoelectric Pzt Thin Films for Microactuator Applications

Poling of pyroelectric thin films

Measurement of the effective transverse piezoelectric coefficient e(31,f) of AlN and Pb(Zr-x,Ti1-x)O-3 thin films