Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 1013-1016 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: There have been numerous reports that Pb(ZrxTi1−x)O3 (PZT) thin-film capacitors with RuO2 electrodes and compositions near the morphotropic phase boundary exhibit minimal decrease in switched polarization with electric-field cycling. We show that the fatigue performance of RuO2//PZT//RuO2 capacitors strongly depends on PZT film composition. Specifically, we demonstrate that the rate of polarization fatigue increases with increasing Ti content for PZT thin films of tetragonal crystal symmetry deposited on RuO2 electrodes. As the Ti content of the PZT films increased, the film gain morphology changed from columnar to granular and the volume percent of a fluorite-type second phase decreased. These microstructural trends and the possibility that the electrode material acts as a sink for oxygen vacancies are discussed to explain the fatigue dependence on B-site cation ratio for PZT films with RuO2 electrodes. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 9250-9257 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We show the alignment of defect dipoles along the direction of the spontaneous polarization in polycrystalline Pb(Zr,Ti)O3 and BaTiO3 ferroelectric ceramics using electron paramagnetic resonance (EPR). The alignment is demonstrated via orientation dependent paramagnetic centers in the polycrystalline materials and computer modeling of the EPR line shapes. It is shown that defect dipoles can become aligned by oxygen vacancy motion in the octahedron about a negatively charged center for the oxygen vacancy-related dipole complexes or by defect displacement and domain realignment in the lattice for isolated defect centers. We find that the alignment is not observed in nonferroelectric materials such as SrTiO3, and is destroyed in ferroelectric materials by heating above the Curie temperature. These observations suggest an interplay between distortion in the unit cell and the ability to align defect dipoles, as is the case more generally for ferroelectric dipole alignment. We also directly observe aligned intrinsic Ti and Pb ion displacements in the ferroelectric Pb(Zr,Ti)O3 perovskite unit cell. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 3975-3980 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Band structure calculations and electron paramagnetic resonance measurements are used to show that Pb states determine many of the electronic properties of Pb(Zr,Ti)O3 ferroelectric materials. The valence-band edge consists of hybridized Pb s and O p states at all compositions. The conduction-band minimum changes from a Ti d-like Γ25' state to a Pb p-like X1 state with increasing Zr content. The Pb p character accounts for the relatively small 0.2 eV increase in band gap in the Pb(Ti,Zr)O3 alloys with Zr content compared to the large 2 eV increase in band gap in Ba(Ti,Zr)O3 alloys. The paramagnetic Pb3+ hole center is found to become deeper and acquire some p character as the Zr content is raised. This is attributed to the change in conduction-band character combined with a local off-center displacement of the Pb3+ ion. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 6695-6702 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Switchable polarization can be suppressed in Pb(Zr,Ti)O3 thin films by optical, thermal, electrical, and reducing processes. The optical suppression effect occurs by biasing the ferroelectric near the switching threshold and illuminating the material with band gap light; the thermal suppression effect occurs by biasing the ferroelectric near the switching threshold and heating the material to ≈100 °C. The electrically induced suppression effect, known as electrical fatigue, occurs by subjecting the ferroelectric capacitor to repeated polarization reversals. We find that the suppressed polarization in these three cases can be restored to essentially its initial polarization value by creating electronic charge carriers in the ferroelectric. This strongly suggests that all three forms of degradation largely involve locking domains by electronic charge trapping at domain boundaries. The fourth form of polarization suppression, a reducing treatment, was obtained by annealing the crystallized PZT films at 400 °C in nitrogen. The suppressed polarization could not be restored by injecting electronic charge into the reduced films, indicating that the mechanism for polarization suppression is different. In this case, it appears as though ionic defects, such as oxygen vacancies, are responsible for locking the domains, and hence, suppressing the polarization. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 4305-4315 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Pb(Zr,Ti)O3 and (Pb,La)(Zr,Ti)O3 thin films and bulk ceramics are shown to exhibit two distinct, but related types of photoinduced changes in their hysteresis behavior: (1) a photoinduced suppression of the switchable polarization and (2) a photoinduced voltage shift. Both effects give rise to stable and reproducible hysteresis changes and, thus, either could be the basis of an optical memory. Both phenomena can be explained by trapping of photogenerated charge at domain boundaries to minimize internal depolarizing fields. The space-charge field that causes the voltage-shift effect is primarily due to the migration and subsequent trapping of electrons. However, the thickness dependence of the voltage shift implies that the trapped charge is not confined to the interface. The voltage-shift kinetics exhibit a stretched-exponential dependence, whereas the polarization-suppression effect follows an exponential time dependence. However, both effects exhibit similar relaxation times. In addition, the relaxation time for the voltage-shift effect decreases with increasing light intensity according to a power-law relationship, τ∝I−n, where 0.67〈n〈0.75.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 4415-4424 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A two-dimensional, lattice-Monte Carlo approach, based upon the energy minimization of an ensemble of electric dipoles, was developed to simulate ferroelectric domain behavior. The model utilizes a Hamiltonian for the total energy based upon electrostatic terms involving dipole–dipole interactions, local polarization gradients, and the influence of applied electric fields. The impact of boundary conditions on the domain configurations obtained was also examined. In general, the model exhibits domain structure characteristics consistent with those observed in a tetragonally distorted ferroelectric. The model was also extended to enable the simulation of ferroelectric hysteresis behavior. Simulated hysteresis loops were found to be very similar in appearance to those observed experimentally in actual materials. This qualitative agreement between the simulated hysteresis loop characteristics and real ferroelectric behavior was also confirmed in simulations run over a range of simulation temperatures and applied field frequencies. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 690-692 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: SrBi2Ta2O9 (SBT) thin films are known to exhibit no polarization fatigue with electric field cycling. However, we have discovered that optical illumination combined with a bias voltage near the switching threshold can result in significant ((approximately-greater-than)90%) suppression of the switchable polarization of SBT thin film capacitors. A similar effect has also been reported for Pb(ZrxTi1−x)O3 (PZT) capacitors. However, it is found that electric field cycling of the optically fatigued SBT capacitors results in near-complete recovery of the suppressed polarization. In contrast, electric field cycling of optically fatigued PZT capacitors does not result in any polarization recovery. These results suggest that optical fatigue in both SBT and PZT capacitors results from pinning of domain walls due to trapping of the photogenerated carriers at domain boundaries, whereas the recovery exhibited by SBT thin films indicates that the domain walls are more weakly pinned in SBT than in PZT thin films. Consequently, the fatigue-free behavior of SBT thin films during electric field cycling can be viewed as a competition between domain wall pinning due to charge trapping and domain wall unpinning by the cycling field; the latter process occurring at least as rapidly as the former. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 272-274 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effect of crystallization temperature on the electrical properties of sol-gel derived Pb(Zr,Ti,Nb)O3 or PNZT capacitors with La0.5Sr0.5CoO3 (LSCO) electrodes has been investigated. It is demonstrated that LSCO//PNZT(4/30/70)//LSCO capacitors can be fabricated at temperatures as low as 550 °C without significant degradation in their ferroelectric and dielectric properties. Lowering the process temperature to 500 °C resulted in substantial degradation in capacitor properties. Nonetheless, all capacitors processed in the 500 °C to 675 °C range exhibited essentially no fatigue up to 5×109 switching cycles. The low temperature processing is significant as it indicates that this ferroelectric capacitor technology is compatible with high density nonvolatile memory architectures. In other words, these process temperatures are low enough to maintain plug integrity and to prevent degradation of the underlying CMOS circuitry in a high density ferroelectric memory. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 2660-2662 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electric field emanating from the surface of a poled ferroelectric (FE) can control the conduction properties of an overlying semiconducting (SC) film; this combination of materials can thus serve as a nondestructive readout (NDRO), nonvolatile memory device. We have characterized prototypes of these devices which utilize semiconducting In2O3 deposited on thin film lead zirconate titanate and bulk BaTiO3 FEs. The remanent state SC resistance in thin film FE NDRO devices is often opposite to that predicted from the known direction of FE polarization. In these cases charge injected from the SC film into the FE and trapped near the interface appears to control the electric field at the SC/FE interface. By contrast, the response of SC films on bulk FEs is largely controlled by just the FE remanent polarization. The measured SC resistance values in the "up'' and "down'' polarization states can be fairly accurately predicted by calculating the accumulation and depletion charge densities from the measured carrier concentrations, mobilities, and FE hysteresis behavior. We also observe a correlation between charge trapping in bulk and thin film of NDRO memory devices and the presence or absence of temperature-bias–stress-induced voltage shifts (imprint) of the FE hysteresis curves. We suggest that the presence of near-interfacial traps in the FE controls both imprint and NDRO memory response. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 1681-1683 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: By systematically poling Pb(Zr,Ti)O3 capacitors to different extents, we observe a linear relationship between the remanent polarization and the magnitude of voltage offsets in the hysteresis curve. This result directly shows that the polarization is the impetus behind voltage shifts and, thus, imprint in ferroelectric capacitors. It is proposed that the increased polarization lowers the electrostatic potential well for the trapping of electrons thereby leading to greater voltage shifts. We also find that the remanent polarization and defect occupancy are temperature dependent which collectively impact the observed voltage offsets measured at elevated temperature. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...