A5050787651- Ferroelectric and Piezoelectric Materials
- Acoustic Wave Resonator Technologies
- Semiconductor materials and devices
- Electronic and Structural Properties of Oxides
- Multiferroics and related materials
- Microwave Dielectric Ceramics Synthesis
- Nuclear materials and radiation effects
- Dielectric properties of ceramics
- Gas Sensing Nanomaterials and Sensors
- Photorefractive and Nonlinear Optics
- Electrical and Thermal Properties of Materials
- Ultrasonics and Acoustic Wave Propagation
- Advancements in Solid Oxide Fuel Cells
- Advanced MEMS and NEMS Technologies
- Ferroelectric and Negative Capacitance Devices
- Dielectric materials and actuators
- Advanced Sensor and Energy Harvesting Materials
Pennsylvania State University
2015-2025
Center for Dielectrics & Piezoelectrics
2015-2023
Millennium Engineering and Integration (United States)
2023
Zn0.64Mg0.36O (ZMO) is a newly discovered ferroelectric oxide with the wurtzite structure. Epitaxial films from 0.036 to 0.5 μm in thickness are grown on Pt/sapphire crystallographic c-axis out of plane. At room temperature, remanent polarization ∼80 μC/cm2 and coercive field ∼3 MV/cm. The strongly temperature dependent up 240 °C pseudo-activation energy 23 ± 0.3 meV, suggesting that reversal occurs through an extrinsic process such as domain wall motion. ZMO can be woken 20 electric cycles...
Abstract Ferroelectric films suffer from both aging and degradation under high ac‐field drive conditions due to loss of polarization with time. In this study, the roles defect chemistry internal electric fields on long‐term stability properties piezoelectric were explored. For purpose, lead zirconate titanate (PZT) a Zr/Ti ratio 52/48 doped Mn‐ (PMZT) or Nb‐ (PNZT) deposited Pt coated Si substrates by sol‐gel method. It was demonstrated that magnitude field is much higher in PMZT compared...
Abstract Strong coupling between polarization ( P ) and strain (ɛ) in ferroelectric complex oxides offers unique opportunities to dramatically tune their properties. Here colossal tuning of ferroelectricity epitaxial KNbO 3 thin films grown by sub‐oxide molecular beam epitaxy is demonstrated. While bulk exhibits three transitions a Curie temperature T c ≈676 K, phase‐field modeling predicts that biaxial as little −0.6% pushes its > 975 decomposition air, for −1.4% strain, 1325 melting...
Abstract Charge transport mechanisms governing DC resistance degradation in ferroelectric films are influenced by defects, particularly oxygen vacancies. This paper demonstrates that vacancies migrate lead zirconate titanate (PZT) under a bias field and contribute to degradation. Model PZT thin were developed which the concentration distribution of controlled via (a) changing dopant type from 1%–4% Mn (acceptor) Nb (donor) or (b) annealing undoped at varying partial pressures PbO. The...
The role of interfacial defect chemistry in time dependent breakdown and associated charge transport mechanisms was investigated for Pb0.99(Zr0.52Ti0.48)0.98Nb0.02O3 (PNZT) films. Electrical degradation strongly on the sign electric field; a significant increase median to failure from 4.8 ± 0.7 7.6 0.4 h observed when top electrode biased negatively compared bottom electrode. improvement electrical reliability Pt/PNZT/Pt films is attributed (1) VO•• distribution across film due PbO...
Many dielectric thin films for energy storage capacitors fail by thermal breakdown events under high‐field drive conditions. The lifetime of the device can be improved conditions where current path within defect regions in dielectrics is eliminated. Self‐healing electrodes were developed depositing a manganese dioxide (MnO 2 ) film between glass substrate and an aluminum film. For this purpose, MnO on boroaluminosilicate fabricated via chemical solution deposition heat‐treated at...
The correlation between defect chemistry, leakage currents, and time-dependent dielectric breakdown was studied for PbZr0.52Ti0.48O3 (PZT) films doped with 0.5, 1, 2, or 4 mol. % Nb. As the samples are nearly intrinsic (that is, close to n- p-type transition), signatures both hole hopping Pb2+ Pb3+ electron trapping by Ti4+ were observed. For all doping levels, dominant conduction mechanism transitioned from Poole–Frenkel emission at lower electric fields Schottky higher fields. field this...
Abstract Thin films based on PbZr 1− x Ti O 3 and K Na NbO are increasingly being commercialized in piezoelectric MEMS due to the comparatively low drive voltages required relative bulk actuators, as well facile approach making sensor or actuator arrays. As these materials incorporated into devices, it is critically important that they operate reliably over lifetime of system. This paper discusses some factors controlling electrical electromechanical reliability lead zirconate titanate...
Highly accelerated lifetime tests of 2 and 3 μm thick potassium sodium niobate [(K0.5, Na0.5)NbO3, KNN] films with different thicknesses were measured under electric fields ranging from 160 to 350 kV/cm temperatures 90 210 °C. The medium time failure (t50) was determined a lognormal distribution plot times up 22 electrodes per measurement condition. activation energy (Ea) for 0.74 ± 0.04 eV 0.92 0.05 the KNN films, respectively. voltage acceleration factor 3.5 0.34 film. But field dependence...
Uniformly acceptor doped Pb(Zr0.48Ti0.52)O3 (PZT) films with 2 mol. % Mg or Fe prepared by chemical solution deposition exhibited decreased dielectric constants and remanent polarizations relative to undoped PZT. For highly accelerated lifetime testing (HALT) at 200 °C an electric field of 300 kV/cm in the up direction, HALT lifetimes (t50) for undoped, Mg-doped, Fe-doped PZT were shortened from 2.81 ± 0.1 0.21 0.54 0.04 h, respectively. Through thermally stimulated depolarization current...
The properties of dielectric and piezoelectric oxides are determined by their processing history, crystal structure, chemical composition, microstructure, dopants (or defect) distribution, defect kinetics. These materials essential in a diverse range applications including aerospace, medical, military, transportation, power engineering, communication, where they used as ceramic discs, thick thin films, multilayer devices, etc. Significant advances understanding the materials, processing,...
The ambient humidity significantly accelerates the degradation of lead zirconate titanate (PZT) films in microelectromechanical systems; cause such is under debate. Here, it shown that chemical solution derived PZT thin-films humid conditions driven by system's electrochemical activity toward water electrolysis. layer stacks with Pt-based electrodes exhibited a faster rate owing to their higher electrocatalytic compared Au. A model proposed based on electrolysis liquid or gaseous H2O,...
Phase pure PbZr0.52Ti0.48O3 (PZT) films with up to 13 mol. % Nb were prepared on Pt-coated Si substrates using chemical solution deposition; charge compensation for was accomplished by reducing the concentration of lead in film. For high doping levels, (1) superoxidation PZT film surface makes PZT/Pt interface more p-type and, hence reduces electron injection over Schottky barrier, (2) bulk transport mechanism changes from trapping Ti4+ hole migration between vacancies, and (3) ionic...
Lead zirconate titanate (PZT) films with high Nb concentrations (6-13 mol%) were grown by chemical solution deposition. In up to 8 mol% Nb, the self-compensate stoichiometry; single phase from precursor solutions 10 PbO excess. Higher induced multi-phase unless amount of excess in was reduced. Phase pure perovskite 13 addition 6 PbO. Charge compensation achieved creating lead vacancies when decreasing level; using Kroger-Vink notation, NbTi• are ionically compensated VPb″ maintain charge...
J. Am. Ceram. Soc., 98[10], 3270–3279. https://doi.org/10.1111/jace.13774 (2015). In the published article above, first sentence in Acknowledgment should be replaced with following: This material is based upon work supported by National Science Foundation, as part of Center for Dielectrics and Piezoelectrics under Grant Nos. IIP-1361571 1361503.