Publications by Paul Muralt | EPFL Graph Search

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Sol-gel deposited Pb(Ti,Zr)O-3 thin films have been used to integrate pyroelectric arrays on silicon. The arrays of 1x12 (element size of 600 x 1100 mm(2)) and 1x50 elements (element size of 140 x 1100 mm(2)) are fabricated by standard photolithography techniques on top of a SiO2/Si3N4 buffer layer which acts as a thermally insulating membrane after micromachining of the silicon. The devices have been characterized using a large aperture blackbody radiation source operating at 423 K. Its radiation is focuss

Voltage offset and built-in polarization were investigated in in-situ reactively sputter deposited PZT thin films on Pt, as a function of composition, doping and cooling conditions. The voltage offset increases with increasing Ti content. Hot-poling treatments show that the voltage offset originates from non-mobile defects. Cooling the samples at various 02 partial pressures leads to a change in lattice parameters and orientation, showing a 'bulk' effect rather than a simple 'surface' effect. While doping w

Degradation of piezoelectric properties has been studied in ferroelectric PZT films by means of optical interferometry. The degradation under de bias and aging of poled films have been observed. The decay of piezoelectric coefficient with time is described by a logarithmic law with aging rates comparable to those of switching polarization. The aging rates are shown to be sensitive to poling conditions and to orientation of the poling field with respect to the direction of preferred polarization. The fatigue

The in-situ growth of PbZrxTi1-xO3 (PZT) and PbTiO3 (PT) thin films by reactive sputter deposition has been investigated for applications with silicon substrates. In-situ deposition from three simultaneously operating magnetron sources was applied. At the selected growth temperature range (550-600 degrees C), self-stabilisation of lead composition by a lar ge desorption rate of Pb on stoichiometric PZT surfaces has been observed. Interlayer mixing was found to be limited to a few monolayers. Both Pt and RuO

In this paper, we experimentally explore the transient negative capacitance effect in ferroelectric high-k gate stacks using multi-ferroelectric domain Si-doped HfO2 with and without the metal plane, MFMIS (TiN/Si:HfO2/TiN/SiO2) and MFIS (TiN/Si:HfO2/SiO2) ...

Processing issues for the fabrication of capacitive micromachined ultrasonic transducer (cMUT) arrays have been studied using surface micromachining. This work focuses on the critical steps of process fabrication such as membrane formation, sacrificial layer properties and vacuum sealing performance of cavity. We describe a four-mask process for the realization of sealed cMUT. We demonstrate that the use of a sacrificial layer with a columnar structure gives a fast etching rate (29 nm s(-1)) in a buffered h

Fabrication of high-density ferroelectric memories requires the growth of the ferroelectric material on the drain contact metal. In standard 0.5 mum technology, tungsten plugs are applied to connect the drain contacts to the first metallization level. In this work, we investigated electrode systems to be applied between sputter deposited, ferroelectric PbZr0.35Ti0.65O3 (PZT) and tungsten. Besides the obvious barrier function of such an electrode system, the texture of the PZT is of interest as well. The rou

PZT (PbZrx Ti1-xO3) thin films have been locally grown by means of sol-gel deposition and local annealing on microhotplates. The microhotplates were based on a stress compensated Si3N4 /SiO2 membranes as structural elements and contained tantalum silicide filaments (Ta5Si3) for resistive heating. Above the filaments, a passivation layer of SiO2, an adhesion layer of Ti/TiO2 and a bottom electrode of Pt were deposited. Due to the low heat conductivity of the membrane, crystallization of the PZT film occurs e

Chemical beam vapour deposition (CBVD) is a thin film deposition technique operated under high vacuum conditions in which film growth occurs through the thermally activated chemical decomposition of precursor molecules at the substrate surface. This techni ...

Polycrystalline aluminum nitride thin films were deposited onto platinum, aluminum, and titanium electrodes by reactive magnetron sputtering in the pulsed direct current mode. The films exhibited all a columnar microstructure and a c-axis texture. The built-in stress and the piezoelectric properties of these films were studied as a function of both the processing conditions and the electrode material. Stress was found to be very much dependent on the growth conditions, and values ranging from strong compres

In this communication we address two issues essential for low-voltage memory applications of ferroelectric thin films: the size effect on polarization switching, and polarization fatigue. According to the proposed concept, both of these phenomena are controlled by local injection of charge into the interfacial layers of the ferroelectric film. In the experimental part of this work, we show that the entrapped charge relaxation can be enhanced by introducing a thin RuO2 layer into the top interface of the Pt/

We report on a novel gas spectrometry technique using pyroelectric thin-him arrays. The 1 x 50 element arrays of PZT are integrated onto silicon using a membrane structure. The experimental characterization of the pyroelectric elements shows both high voltage and current responses in defined frequency ranges. Mounting the array as a detector in a commercial spectrometer, we demonstrate its capability of detecting the infrared absorption curves of gases by the example of CO2. (C) 1998 Elsevier Science S.A. A

The mass sensitivity of an AlN thin film resonators operated in air at 6-8 GHz has been investigated in theory and experiment. The 30 x 30 mu m wide resonators included a 180-300 nm thick, highly oriented AlN thin film, bottom and top electrode, and an aco ...

The influence of film thickness on the material properties of aluminum nitride (AlN) thin films deposited on Pt(111) electrodes has been investigated experimentally by means of x-ray diffraction, dielectric response, atomic force microscopy, interferometry measurement of effective d(33), and residual stress measurement. The thickness was varied between 35 nm and 2 mum. Full width at mid-height of the rocking curve decreased from 2.60 to 1.14degrees, rms roughness increased from 3.8 to 18.6 Angstrom, the eff

A novel concept for shear mode Bulk Acoustic Resonators (BAR) is presented. It is based on c-axis oriented AlN thin films grown on silicon dioxide thin films, combined with interdigitated electrodes. Such a structure leads to an excitation of mainly shear ...

We report on a photonic crystal (PhC) etched into a 380 nm thick lithium niobate (LN) thin film deposited on a MgO substrate by pulsed laser deposition. The transmission properties of this device were assessed by optical near-field measurements and compare ...

Piezoelectric membranes consisting of PbZrxTi1-xO3 (PZT) films on silicon diaphragms have been fabricated, investigated, and applied for micromotors. The PZT films were deposited by sputtering and sol gel techniques. Resonance amplitudes of up to 1000 nm/V have been measured for 16 mu m thick, 2 mm diameter membranes with 0.6 mu m PZT. The PZT films show a preferred direction of polarization, which seems to depend on the deposition technique. Membranes of 4 mm diameter have been successfully applied as a vi

AlN thin films were grown by reactive sputtering on amorphous SiO2 thin films. Film texture, x-ray rocking curve width, mechanical stress, and the clamped piezoelectric constant d33,f were studied as a function of rf bias power and substrate roughness. A h ...

DC bias dependent acoustic resonance phenomena have been observed in micromachined tunable thin film capacitors based on Ba0.3Sr0.7TiO3 (BST) thin films. The antiresonance frequency is only weakly dc bias dependent, whereas the resonance frequency exhibits a strong dependence on the applied dc bias. The resonance frequency shifted by 0.8% for a frequency of about 3.44 GHz and an applied of 333 KV/cm. At the same time the electromechanical coupling constant k(t)(2) increased to 1.8%. The experimental observa

The nature and the role of 1 to 5 nm thick TiO2 seed layers for the growth of textured PbTiO3 and Pb(Zr, Ti)O-3 thin films on textured Pt(111) thin film substrates have been studied. Under otherwise identical in situ sputter deposition process conditions, the PbTiO3 texture could be turned from (100) to (111) orientation by adding the seed layer. This is demonstrated by patterning the TiO2 film. Auger electron spectroscopy and x-ray photoemission spectroscopy showed that the seed layer was a continuous TiO2

Paul Muralt

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Pyroelectric thin film sensor arrays integrated on silicon

Origin of voltage offset and built-in polarization in in-situ sputter deposited PZT thin films

Interferometric study of piezoelectric degradation in ferroelectric thin films

In-situ sputter deposition of PT and PZT films on platinum and RuO2 electrodes

Transient Negative Capacitance of Silicon-doped HfO2 in MFMIS and MFIS structures: experimental insights for hysteresis-free steep slope NC FETs

Optimization of the fabrication of sealed capacitive transducers using surface micromachining

Tungsten based electrodes for stacked capacitor ferroelectric memories

Local growth of sol-gel films by means of microhotplates

A combinatorial chemical beam vapour deposition approach to tune the electrical conductivity of Nb:TiO2 films via Si co-doping

Stress and piezoelectric properties of aluminum nitride thin films deposited onto metal electrodes by pulsed direct current reactive sputtering

Downscaling of Pb(Zr,Ti)O-3 film thickness for low-voltage ferroelectric capacitors: Effect of charge relaxation at the interfaces

Gas spectrometry based on pyroelectric thin-film arrays integrated on silicon

Bulk acoustic wave resonator operating at 8 GHz for gravimetric sensing of organic films

Thickness dependence of the properties of highly c-axis textured AlN thin films

PMBAR* - shear mode TFBAR based on (001)AlN thin film Piezo-Modulated Bulk Acoustic wave Resonator

Strong improvement in the photonic stop-band edge sharpness of a lithium niobate photonic crystal slab

Fabrication and characterization of PZT thin films for micromotors

Highly piezoelectric AlN thin films grown on amorphous, insulating substrate

DC bias dependent shift of resonance frequencies in BST thin film membranes

Texture control of PbTiO3 and Pb(Zr,Ti)O-3 thin films with TiO2 seeding