Publications by Paul Muralt | EPFL Graph Search

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In this work, we investigate a new method of low-pressure lamination of low-temperature cofired ceramic (LTCC) tapes, by pre-coating with specially-formulated adhesive layers. This allows fabrication of intricate structures that would be destroyed by high lamination pressures, yet preserves compatibility with standard processing operations, such as blanking, laser cutting, punching, via filling and screen printing. Techniques proposed previously are application of adhesive tapes, solvents or glues. These me

Even though many studies on the field cycling behavior of ferroelectric hafnium oxide have recently been published, the issue is still not fully understood. The initial increase of polarization during first cycles is explained by different theoretical and ...

Thin film piezoelectric materials offer a number of advantages in microelectromechanical systems (MEMS), due to the large motions that can be generated, often with low hysteresis, the high available energy densities, as well as high sensitivity sensors with wide dynamic ranges, and low power requirements. This paper reviews the literature in this field, with an emphasis on the factors that impact the magnitude of the available piezoelectric response. For non-ferroelectric piezoelectrics such as ZnO and AlN,

We present a far infrared gas spectrometer which uses a thin film pyroelectric detector integrated on silicon. The detector is in-house fabricated and consists of 1 x 50 elements of sol-gel deposited, zirconium rich lead titanate (PZT) which are suspended on a submicron membrane for thermal insulation. The detector shows a detectivity of 16 mu A/W and is mounted into a Oriel monochromator fitted with gratings for the 3-5 mu m and the 8-12 mu m range, respectively. The infrared radiation is emitted by a hot

This article reports on the state-of-the-art of the development of aluminum nitride (AlN) thin-film microelectromechanical systems (MEMS) with particular emphasis on acoustic devices for radio frequency (RF) signal processing. Examples of resonant devices ...

Ferroelectric capacitive devices for memory and MEMS applications require patterned ferroelectric thin films with high anisotropic etched features. In this paper, physical and chemical parameters during etching of Pb(Zr0.53Ti0.47)O-3 (PZT) by a dual frequency ECR/RF reactor have been investigated. The removal characteristics of blanket films and films with a patterned mask were investigated as a function of gas chemistry (Ar, halogen gases), substrate bias RF power and working pressure (from 5 x 10(-4) Pa t

High-Q, bulk acoustic wave composite resonators based on a symmetric layer sequence Of SiO2-A1N-SiO2 sandwiched between electrodes have been developed. Acoustic isolation was achieved by means of deep silicon etching to obtain membrane type TFBAR's. Three different device versions were investigated. The SiO2 film thicknesses was varied (70nm, 310mn and 770nm) while the piezoelectric A1N film had a constant thickness of 1.2 mu m. The sputter deposited A1N film grown on the amorphous, sputter deposited SiO2 l

Ferroelectric thin films for memory and MEMS applications require noble metal or refractory metal oxide electrodes. In this paper, physical and chemical mechanisms during platinum etching by a dual frequency ECR/RF reactor have been investigated. An ion beam was generated by means of a 50 mm diameter ECR-gun directed towards the substrate. The latter was placed on a RF powered electrode for discharging and local activation of reactive gas species. The removal characteristics of blanket platinum films and pl

Ferroelectric thin films for memory and MEMS applications require noble metal or refractory metal oxide electrodes. In this paper, physical and chemical parameters during etching of RuO2 and Pr by a dual frequency ECR/RF reactor have been investigated. The removal characteristics of blanket films and films with a patterned mask (photoresist or SiO2 masks) were investigated as a function of gas chemistry (Ar, O-2, halogen gases), ion beam energy (ion extraction/acceleration voltages), substrate bias RF power

Polarization reversal in BiFeO3 (BFO) thin films in a parallel-plate capacitor configuration has been explored using piezo-force microscopy (PFM). Through-electrode mapping of the local piezoresponse allows for direct observation of the domain growth, whic ...

(001)-textured AIN thin films as needed for longitudinal bulk acoustic wave (BAW) devices exhibit large mechanical stress variations and large orientation variation as a function of growth substrate properties. We prepared thin silicon and silicon dioxide layers by sputter deposition to increase the roughness of thermal oxide films. The amorphous silicon films exhibited an rms roughness of 0.1 to 1.1 nm and the amorphous SiO2 an rms roughness ranging from 0.2 to 3.8 nm. In the following we studied stress, o

Pb(Zr,Ti)03 thin films with compositions close to the morphotropic phase boundary deposited onto electroded Si substrates have potential for use in ferroelectric memories, sensors and micromechanical devices. The microstructures of such films prepared by in-situ reactive sputtering have been characterised using transmission electron microscopy. (001) oriented films, which were essentially free from second phases, could be prepared by using Ti-rich seed layers. The interfaces between the seed layers and the

A PZT, Pb(Zr,Ti)O-3 (40:60), ferroelectric layer has been successfully deposited onto a Al0.3Ga0.7N/GaN heterostructure with a 2DEG, two dimensional electron gas. Due to the chemical and temperature stability of AlGaN/GaN it was possible to implement the c ...

Relaxor Pb(Sc-12/Ta-1/2)O-3 (PST) thin films have been prepared using mixed alkoxide and acetate precursors on TiO2/Pt/TiO2/SiO2/Si substrates. Relaxor behavior as evidenced by frequency dispersion of the permittivity as a function of temperature was observed, as well as a thickness dependence of the dielectric constant. The highest values of dielectric constant were observed for the thicker 650 nm samples displaying a room temperature dielectric constant near 2000, with a loss tangent of 0.3% at 1 kHz. The

Piezoelectric coatings of PbZrxTi1-xO3 (PZT) were deposited on standard telecommunication fibers. The PZT coatings were produced by reactive de magnetron sputtering of metal targets in pure oxygen atmosphere. The deposition was carried out at substrate temperatures between 500 and 600 degrees C. Film thicknesses are in the range of 1300 to 1500 nm. The device structure under investigation is of the Ti/Pt/PZT/Au type. X-ray diffraction (XRD) scanning electron microscopy (SEM), and electrical measurements wer

Some oxygen defective metal oxides, such as cerium and bismuth oxides, have recently shown exceptional electrostrictive properties that are even superior to the best performing lead-based electrostrictors, e.g. lead-magnesium-niobates (PMN). Compared to pi ...

Lead zirconate titanate (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 the former exploit the longitudinal pie ...

For the first time we have characterized a micromotor driven by a piezoelectric PZT (PbZrxTi1-xO3) thin film. Sputter and sol-gel techniques have been applied for the deposition of the PZT films onto a silicon stator membrane, which is 20-30 mu m thick and has a diameter of 4 mm. The amplitudes of the membrane deflections are measured by means of laser interferometry. They are as large as 800 nm V-1 at the first resonance (26 kHz) and 60 nm V-1 at 1 kHz. This is one order of magnitude larger than previously

A five-layer stack of lead zirconate titanate (PZT) thin films with Pt electrodes was fabricated for potential applications in nanoactuator systems. The 1 mu m thick PZT films were deposited by a sol-gel technique, the platinum electrodes by sputtering. Th ...

The paper reviews different aspects of deposition, integration, and device fabrication of PbZrxTi1-xO3 (PZT) films for application in micromechanical systems. The deposition of such films and the principal processes for their integration onto silicon substrates are now fairly well mastered. Current efforts concentrate on tailoring the film properties for the various applications, and on optimization of the device designs and patterning processes. Current work on an ultrasonic micromotor and a pyroelectric I

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Lamination of LTCC at low pressure and moderate temperature using screen-printed adhesives

Domain Pinning: Comparison of Hafnia and PZT Based Ferroelectrics

Thin film piezoelectrics for MEMS

Gas spectrometry based on a pyroelectric thin film array

Piezoelectric aluminum nitride thin films for microelectromechanical systems

Mechanisms of Pb(Zr0.53Ti0.47)O-3 thin film etching with ECR/RF reactor

Fabrication and properties of high-Q AlN/SiO2 composite TFBAR's for above IC oscillators

Etching of platinum thin films with dual frequency ECR/RF reactor

Etching of RuO2 and Pt thin films with ECR/RF reactor

Polarization Reversal in BiFeO3 Capacitors: Complex Behavior Revealed by PFM

Growth study of AlN on amorphous films with defined roughness

Microstructural characterisation of Pb(Zr,Ti)O3 thin films deposited by in-situ reactive sputtering

Ferroelectric Gate on AlGaN/GaN Heterostructures

Dielectric response and structural features of Pb(Sc1/2Ta1/2)O-3 (PST) sol-gel derived thin films

PZT coated optical fibers for acousto-optical modulation

Effect of oxygen defects blocking barriers on gadolinium doped ceria (GDC) electro-chemo-mechanical properties

Comparison of Lead Zirconate Titanate Thin Films for Microelectromechanical Energy Harvester With Interdigitated and Parallel Plate Electrodes

Fabrication and Characterization of Pzt Thin-Film Vibrators for Micromotors

High Piezoelectric Longitudinal Coefficients in Sol-gel PZT Thin Film Multilayers

PZT thin films for micro sensors and actuators