scholarly journals Voltage Shifts and Defect-Dipoles in Ferroelectric Capacitors

1996 ◽  
Vol 433 ◽  
Author(s):  
W. L. Warren ◽  
G. E. Pike ◽  
D. Dimos ◽  
K. Vanheusden ◽  
H.N. Al-Shareef ◽  
...  
Keyword(s):  
Charge Trapping ◽  
Spatial Location ◽  
Ferroelectric Materials ◽  
Electron Trapping ◽  
Defect Dipole ◽  
Electrode Interface ◽  
Dc Bias ◽  
Ferroelectric Capacitors ◽  
Lead Vacancy ◽  
Common Defect

AbstractWe review the processes and mechanisms by which voltage offsets occur in the hysteresis loop of ferroelectric materials. Simply stated, voltage shifts arise from nearinterfacial charge trapping in the ferroelectric. We show that the impetus behind voltage shifts in ferroelectric capacitors is the net polarization, with the net polarization being determined by the perovskite and the aligned defect-dipole components. Some common defect-dipoles in the PZT system are lead vacancy-oxygen vacancy complexes. One way to change the net polarization in the ferroelectric is to subject the PZT capacitor to a dc bias at elevated temperature; this process is spectroscopically shown to align defect-dipoles along the direction of the applied electric field. The alignment of defect-dipoles can strongly impact several material properties. One such impact is that it can lead to enhanced voltage shifts (imprint). It is proposed that the net polarization determines the spatial location of the asymmetrically trapped charge that are the cause for the voltage shifts. An enhanced polarization at one electrode interface can lead to larger voltage shifts since it lowers the electrostatic potential well for electron trapping, i.e., more electron trapping can occur. Defect-dipole alignment is also shown to increase the UV sensitivity of the ferroelectric.

Electronic Impact of Inclusions in Diamond

2009 ◽  
Vol 1203 ◽  
Author(s):  
Erik M. Muller ◽  
John Smedley ◽  
Balaji Raghothamachar ◽  
Mengjia Gaowei ◽  
Jeffrey W. Keister ◽  
...  
Keyword(s):  
Charge Trapping ◽  
Secondary Phase ◽  
Surface Region ◽  
Phase Region ◽  
Electron Trapping ◽  
Near Surface ◽  
X Ray ◽  
Photoconductive Gain ◽  
Single Crystal Diamond ◽  
Topography Data

AbstractX-ray topography data are compared with photodiode responsivity maps to identify potential candidates for electron trapping in high purity, single crystal diamond. X-ray topography data reveal the defects that exist in the diamond material, which are dominated by non-electrically active linear dislocations. However, many diamonds also contain defects configurations (groups of threading dislocations originating from a secondary phase region or inclusion) in the bulk of the wafer which map well to regions of photoconductive gain, indicating that these inclusions are a source of electron trapping which affect the performance of diamond X-ray detectors. It was determined that photoconductive gain is only possible with the combination of an injecting contact and charge trapping in the near surface region. Typical photoconductive gain regions are 0.2 mm across; away from these near-surface inclusions the device yields the expected diode responsivity.

Macroscopic and microscopic picture of negative capacitance operation in ferroelectric capacitors

Nanoscale ◽  
2021 ◽  
Author(s):  
David Esseni ◽  
Riccardo Fontanini
Keyword(s):  
Landau Theory ◽  
Ferroelectric Materials ◽  
Negative Capacitance ◽  
Stabilization Condition ◽  
Microscopic Picture ◽  
Ferroelectric Capacitors

The negative capacitance (NC) operation of ferroelectric materials has been originally proposed based on a homogeneous Landau theory, leading to a simple NC stabilization condition expressed in terms of macroscopic...

scholarly journals Perovskite Ferroelectric

2021 ◽  
Author(s):  
Paramjit Kour ◽  
Sudipta Kishore Pradhan
Keyword(s):  
Thin Film ◽  
Fundamental Principle ◽  
Dielectric Behavior ◽  
Ferroelectric Materials ◽  
Frequency Filter ◽  
Pyroelectric Effect ◽  
Perovskite Materials ◽  
Wide Range ◽  
Ferroelectric Hysteresis ◽  
Ferroelectric Capacitors

The spectrums of properties exhibited by ferroelectric materials are dielectric, ferroelectric, piezoelectric and pyroelectric effect. This is the makes these materials to have a wide range of useful application. Infrared detectors are used pyroelectric effect of ferroelectric materials. It is used in nonvolatile memories due to have ferroelectric hysteresis. Its piezoelectric properties make them useful for actuator, radio frequency filter, sensor, and transducer. Ferroelectric capacitors are used, their good dielectric behavior. According to the necessity of the system they are available in different form such as single crystals, ceramics, thin film, and polymer, composite. The diversity of properties ferroelectric materials always attracted the attention of engineers and researchers. Size reduction of this material from micro to nanoscale established an enormous consideration to develop nanotechnology. Its vast use of different filed imposed the in detail research in adding to the development of processing and characterization method. This chapter will put some light on some fundamental principle of ferroelectricity, the list of perovskite materials and their application.

scholarly journals Electrocaloric Response of Ferroelectric Material Applicable as Electrothermal Transducer

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Saber Mohammadi ◽  
Akram Khodayari ◽  
Arash Ahmadi
Keyword(s):  
Heat Flux ◽  
Electric Field ◽  
Boundary Conditions ◽  
Ferroelectric Material ◽  
Ferroelectric Materials ◽  
Numerical Results ◽  
Temperature Range ◽  
Periodic Electric Field ◽  
Ferroelectric Capacitors

Electrocaloric response of the PMN-10PT is measured experimentally and compared with the numerical results. Based on the compatibility of the experimental and numerical results, feasibility of using ferroelectric materials as an electrothermal transducer has been investigated. In this study, electrocaloric response of three different ferroelectric capacitors (PMN-10PT, PMN-25PT, and PZN-4.5PT) under an applied periodic electric field have been investigated. Alternative switching of the electrocaloric elements with specific boundary conditions generates a directed heat flux. It can be concluded that each ferroelectric material can be used as a transducer in a special temperature range that in which it has good electrocaloric response.

Degradation Mechanisms in Ferroelectric and High-Permittivity Perovskites

MRS Bulletin ◽  
1996 ◽  
Vol 21 (7) ◽  
pp. 40-45 ◽  
Author(s):  
William L. Warren ◽  
Duane Dimos ◽  
Rainer M. Waser
Keyword(s):  
Thin Films ◽  
Random Access ◽  
Charge Trapping ◽  
Ferroelectric Materials ◽  
Degradation Mechanisms ◽  
High Permittivity ◽  
Polarization Voltage ◽  
Degradation Processes ◽  
Wide Range ◽  
Resistance Degradation

Due to the importance of ferroelectric and high-permittivity perovskite thin films for a wide range of applications, there has been extensive research devoted to understanding the mechanisms responsible for the degradation observed with time, temperature, and/or external field stress. The three most important degradation phenomena for ferroelectric materials such as Pb(Zr, Ti)O3 (PZT) and BaTiO3 are ferroelectric fatigue, ferro-electric aging, and resistance degradation. Ferroelectric fatigue is the loss of switchable polarization by repeated polarization reversals. Ferroelectric aging is characterized by a spontaneous change with time in the polarization-voltage (P-V) response. Resistance degradation is a deterioration of the insulating properties of a dielectric under direct-current (dc) bias and elevated temperature.These degradation processes ultimately limit the lifetime and reliability of devices that use ferroelectric and high-permittivity perovskite dielectrics. Fatigue and aging lead to reliability concerns for electronic (nonvolatile memories), piezo-electric, electro-optic, and pyroelectric applications. Likewise resistance degradation typically limits the lifetime of ceramic capacitors and high-dielectric constant thin films such as (Ba, Sr)TiO3, which is the principal candidate material for very high-density dynamic random-access memories (DRAMs).Because of the importance of these degradation processes, it is critical to understand them and to develop methods of eliminating or mitigating their effects. By combining results from studies on thin films with ones on ceramics and single crystals, a consistent picture of the mechanisms involved in these degradation processes is emerging. In this article, we discuss these degradation mechanisms with particular emphasis on the interaction between ferroelectric domains and charge trapping and the role of oxygen vacancies and associated defect dipoles.

scholarly journals Ferroelectricity in Si-Doped Hafnia: Probing Challenges in Absence of Screening Charges

Nanomaterials ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1576 ◽  
Author(s):  
Umberto Celano ◽  
Andres Gomez ◽  
Paola Piedimonte ◽  
Sabine Neumayer ◽  
Liam Collins ◽  
...  
Keyword(s):  
Hysteresis Loops ◽  
Charge Trapping ◽  
Ferroelectric Materials ◽  
Oxide Surface ◽  
Material System ◽  
Existing Problems ◽  
Spatially Resolved ◽  
Non Volatile Memory ◽  
Piezoelectric Effects ◽  
Si Doped

The ability to develop ferroelectric materials using binary oxides is critical to enable novel low-power, high-density non-volatile memory and fast switching logic. The discovery of ferroelectricity in hafnia-based thin films, has focused the hopes of the community on this class of materials to overcome the existing problems of perovskite-based integrated ferroelectrics. However, both the control of ferroelectricity in doped-HfO2 and the direct characterization at the nanoscale of ferroelectric phenomena, are increasingly difficult to achieve. The main limitations are imposed by the inherent intertwining of ferroelectric and dielectric properties, the role of strain, interfaces and electric field-mediated phase, and polarization changes. In this work, using Si-doped HfO2 as a material system, we performed a correlative study with four scanning probe techniques for the local sensing of intrinsic ferroelectricity on the oxide surface. Putting each technique in perspective, we demonstrated that different origins of spatially resolved contrast can be obtained, thus highlighting possible crosstalk not originated by a genuine ferroelectric response. By leveraging the strength of each method, we showed how intrinsic processes in ultrathin dielectrics, i.e., electronic leakage, existence and generation of energy states, charge trapping (de-trapping) phenomena, and electrochemical effects, can influence the sensed response. We then proceeded to initiate hysteresis loops by means of tip-induced spectroscopic cycling (i.e., “wake-up”), thus observing the onset of oxide degradation processes associated with this step. Finally, direct piezoelectric effects were studied using the high pressure resulting from the probe’s confinement, noticing the absence of a net time-invariant piezo-generated charge. Our results are critical in providing a general framework of interpretation for multiple nanoscale processes impacting ferroelectricity in doped-hafnia and strategies for sensing it.

Defect Creation and Electron Trapping in Single Crystal and Sintered Alumina by Electron Beam Irradiation

1992 ◽  
Vol 279 ◽  
Author(s):  
D. L. Carroll ◽  
D. L. Doering ◽  
P. Xiong-Skiba
Keyword(s):  
Electron Beam ◽  
Single Crystal ◽  
Electron Beam Irradiation ◽  
Thermionic Emission ◽  
Charge Trapping ◽  
Binding Energies ◽  
Electron Trapping ◽  
Excess Charge ◽  
Beam Irradiation ◽  
Core Electron

ABSTRACTElectron beam irradiation of oxides produces electron trapping states which store excess charge. Thermionic emission of this charge occurs during heating with emission peak temperatures related to binding mechanisms and energies. We present thermionic emission results which show both intrinsic and beam induced trapping states in OC-Al2O3 (sapphire) and sintered alumina. Five states have been identified with thermionic emission peaks at temperatures between -50°C and 500°C. Two states are electron beam induced and occur only for electron beam energies above fixed thresholds. These thresholds appear to correlate to with the Is core electron binding energies for oxygen and aluminum. The emission peaks from the sintered material are about 10 fold greater in intensity and slightly broadened in comparison to the single crystal. This suggests that structure plays an important role in charge trapping. Emission was also extremely sensitive to sample treatments such as annealing before electron irradiation.

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