Publications by Nava Setter | EPFL Graph Search

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The dielectric response in Bi4Ti3O12 single crystals was studied at subswitching conditions at relative low temperatures (20-250 degrees C) and frequencies (100 mHz to 10kHz) both in-plane and out-of-plane. Electron-holes are likely to be the major charge ...

Recent progress in integrating ferroelectrics directly on silicon opens the exciting possibility of implementing ferroelectric-semiconductor devices. One of the major problems for such integration is the instability of the ferroelectric state in very thin films, which is mainly controlled by the screening ability of the ferroelectric-semiconductor interface. We show here that the presence of built-in potential in the semiconductor can strongly influence the screening ability of the interface. The built-in p

The phase transition behaviors of (1-x)Pb(Yb1/2Nb1/2)O3-xBa(Yb1/2Nb1/2)O-3 (PBYN) solid solution system (0 less than or equal tox less than or equal to0.30) have been investigated by X-ray diffraction, permittivity and E-P hysteresis loop measurements. In the solid solution, for x less than or equal to0.10, the transition shows a normal first-order paraelectric (PE)-antiferroelectric (AFE) behavior and its AFE crystal structure is orthorhombic. The transition temperature gradually decreases with the increas

The influence of Ta, Ti and TiO2 adhesion layers with Pt bottom electrodes and the deposition temperature of the metallization on the nucleation and growth of sol-gel derived Pb(Zr0.53Ti0.47)O-3 thin films is reported. Several different PZT annealing profiles were simultaneously investigated to determine the role of PZT annealing on resultant PZT film microstructures for a given metallization. The adhesion layer was found to primarily influence PZT grain size. Largest grain sizes were observed for substrate

The piezoelectric properties of tetragonal BaTiO3 (BTO) crystals with a high density of 90° twin domain boundaries were experimentally investigated by Wada and Tsurumi (2004 Br. Ceram. Trans. 103 93). These crystals with engineered dense domain structures exhibit significantly larger intrinsic d33 and d31 coefficients than in mono-domain crystals. This phenomena was studied theoretically and several enhancement mechanisms (domain wall broadening, polarization tilting) were suggested in the past, but no sati

We demonstrate charge-mediated and non-volatile control of anisotropic magnetoresistance (AMR) in a dilute magnetic semiconductor (Ga,Mn)(As, P) with an integrated polymer ferroelectric gate. The persistent electric field associated with switchable polariz ...

Structural investigations of SrTiO3 thin films deposited by pulsed laser ablation onto MgO and LaAlO3 substrates are presented. The residual strain along the c -axis (the growth direction) was evaluated with conventional X-ray diffraction. Evaluation of the in-plane strain was accomplished with grazing-incidence X-ray diffraction. The unit cell of the STO film on LAO substrate had an orthorhombic structure with a coexistence of compressive strain along a -axis and tensile strain along b -axis. The film on a

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

Unlike Pb(Mg1/3Nb2/3)O-3 and similar ferroelectric relaxors which never truly become ferroelectric at zero-field, disordered Pb(Sc1/2Ta1/2)O-3 (PST) is a relaxer that spontaneously transforms into a ferroelectric phase. The control of the degree of order of the B-site cations in PST by appropriate heat treatment has been often used to demonstrate the influence of chemical disorder on the dielectric properties of ferroelectrics. Here it is shown that, in PST, disorder itself is not sufficient to prevent a ma

It was noticed long time ago that the dielectric permittivity of BaTiO3 single crystals in the rhombohedral phase varies from observation to observation, but the microstructure mechanism behind this phenomenon remained unclear. We show that the variations in susceptibility can be related to the variable domain structure introduced by different pre-treatments at higher temperatures: Electrical depoling at room temperature leads to nano-sized domains and ultrahigh susceptibility in rhombohedral phase, whereas

The structural property and electric field response of a single perovskite PbTiO3 nanowire were investigated by means of synchrotron X-ray diffraction (XRD) with a micro X-ray beam. XRD 0-20 patterns and Raman spectra confirmed the formation of the perovsk ...

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

It was recently suggested, basing on the analysis of a wide range of macroscopic experimental results([1-4]), that fatigue in ferroelectric thin film capacitors, particularly in the case of PZT with metallic electrodes (Pt), must be related to the freezing of polarisation domains where the dielectric properties of the lattice remain nearly unchanged and the orientation of the locked domains can show a strong preferential direction. According to these results it was also possible to propose a simple method t

The dielectric behaviour and structure of the BaxSr1-x(Zn1/3Nb2/3)O3 (BSZN) solid solution have been investigated with the intention of understanding an anomaly which exists in the temperature coefficient of the dielectric constant (tau(epsilon)) at x almost-equal-to 0.5. A correlation between tau(epsilon) and the occurrence of O-octahedra tilts has been established.

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

This communication reports on the growth of highly uniform KNbO3 nanowires exhibiting a narrow diameter distribution around 60 nm and a length-to-width ratio up to 100. The nanowires were prepared by a hydrothermal route, which enables simple, gram-scale p ...

Temperature dependences of the optic phonons in PbSc1/2Ta1/2O3 (PST) sol-gel films deposited on sapphire substrates were studied by means of Fourier transform far-infrared transmission spectroscopy in the temperature range of 20-900 K. Four films displayin ...

The influence of ultraviolet (UV) illumination on piezoelectric properties is investigated in lead zirconate titanate (PZT) thin films. It is found that the poling procedure is more effective when the film is exposed to a broadband UV light in the presence of a high electric field. Piezoelectric coefficients are increased and aging rates are decreased as compared to poling in dark conditions. Both an internal bias field and a polarization offset are observed in the piezoelectric hysteresis loops. The mechan

Miniaturization of conventional field effect transistors (FETs) approaches the fundamental limits beyond which opening and closing the transistor channel require higher gate voltage swing and cause higher power dissipation and heating. This problem could b ...

The electrical conductivity of SrBi4Ti4O15 (SBT) has been measured under controlled oxygen partial pressure. Both acceptor and donor doping effects were studied using de conductivity and impedance measurements. In addition to the ceramic samples with random grain orientation, grain oriented samples were prepared by hot forging. It has been shown that the conductivity of SBT is electronic p type in air at low temperature and it is n type at high temperature (greater than or equal to 700 degrees) up to 1 atm

Nava Setter

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Conductivity and Ferroelectric Hysteresis in Bi4Ti3O12 Single Crystals Around Room Temperature

Improved Screening Ability of Ferroelectric-Semiconductor Interface

Phase transition behaviors of (1-x)Pb(Yb1/2Nb1/2) O-3-xBa(Yb1/2Nb1/2)O-3 ceramics

Microstructure of PZT sol-gel films on Pt substrates with different adhesion layers

The stress-assisted enhancement of piezoelectric properties due to mechanically incompatible domain structures in BaTiO3

Non-volatile ferroelectric gating of magnetotransport anisotropy in (Ga,Mn)(As,P)

Structural investigation of thin SrTiO3 films grown on MgO and LaAlO3 substrates

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

Role of Defects in the Ferroelectric Relaxer Lead Scandium Tantalate

Unusual dielectric behavior and domain structure in rhombohedral phase of BaTiO3 single crystals

Structural Property and Electric Field Response of a Single Perovskite PbTiO3 Nanowire Using Micro X-ray Beam

Chemical analysis of lead zirconium titanium oxide films

Microscopic observation of "region by region" polarisation domains freezing during fatigue of the Pt-PZT-Pt system

DiP256: The Temperature-Coefficient of the Relative Permittivity of Complex Perovskites and Its Relation to Structural Transformations

Thin piezoelectric films for micro-electromechanical components

Growth of single-crystalline KNbO3 nanostructures

Far-infrared soft-mode behavior in PbSc1/2Ta1/2O3 thin films

Photoinduced poling of lead titanate zirconate thin films

Static negative capacitance of a ferroelectric nano-domain nucleus

Electrical conductivity of strontium bismuth titanate under controlled oxygen partial pressure