Transport and Fatigue Properties of Ferroelectric Polymer P(VDF-TrFE) For Nonvolatile Memory Applications

Handle URI:
http://hdl.handle.net/10754/244572
Title:
Transport and Fatigue Properties of Ferroelectric Polymer P(VDF-TrFE) For Nonvolatile Memory Applications
Authors:
Hanna, Amir
Abstract:
Organic ferroelectrics polymers have recently received much interest for use in nonvolatile memory devices. The ferroelectric copolymer poly(vinylidene fluoride- trifluoroethylene) , P(VDF-TrFE), is a promising candidate due to its relatively high remnant polarization, low coercive field, fast switching times, easy processability, and low Curie transition. However, no detailed study of charge injection and current transport properties in P(VDF-TrFE) have been reported in the literature yet. Charge injection and transport are believed to affect various properties of ferroelectric films such as remnant polarization values and polarization fatigue behavior.. Thus, this thesis aims to study charge injection in P(VDF-TrFE) and its transport properties as a function of electrode material. Injection was studied for Al, Ag, Au and Pt electrodes. Higher work function metals such as Pt have shown less leakage current compared to lower work function metals such as Al for more than an order of magnitude. That implied n-type conduction behavior for P(VDF-TrFE), as well as electrons being the dominant injected carrier type. Charge transport was also studied as a function of temperature, and two major transport regimes were identified: 1) Thermionic emission over a Schottky barrier for low fields (E < 25 MV/m). 2) Space-Charge-Limited regime at higher fields (25 < E <120 MV/m). We have also studied the optical imprint phenomenon, the polarization fatigue resulting from a combination of broad band optical illumination and DC bias near the switching field. A setup was designed for the experiment, and validated by reproducing the reported effect in polycrystalline Pb(Zr,Ti)O3 , PZT, film. On the other hand, P(VDF-TrFE) film showed no polarization fatigue as a result of optical imprint test, which could be attributed to the large band gap of the material, and the low intensity of the UV portion of the arc lamp white light used for the experiment. Results suggest using high work function metals for a memory application, as lower leakage would enhance fatigue endurance for P(VDF-TrFE) film.
Advisors:
Alshareef, Husam N.
Committee Member:
Manchon, Aurelien ( 0000-0002-4768-293X ) ; Schwingenschlögl, Udo ( 0000-0003-4179-7231 )
KAUST Department:
Physical Sciences and Engineering (PSE) Division
Program:
Materials Science and Engineering
Issue Date:
Jun-2012
Type:
Thesis
Appears in Collections:
Theses; Physical Sciences and Engineering (PSE) Division; Materials Science and Engineering Program

Full metadata record

DC FieldValue Language
dc.contributor.advisorAlshareef, Husam N.en
dc.contributor.authorHanna, Amiren
dc.date.accessioned2012-09-18T06:56:21Z-
dc.date.available2012-09-18T06:56:21Z-
dc.date.issued2012-06en
dc.identifier.urihttp://hdl.handle.net/10754/244572en
dc.description.abstractOrganic ferroelectrics polymers have recently received much interest for use in nonvolatile memory devices. The ferroelectric copolymer poly(vinylidene fluoride- trifluoroethylene) , P(VDF-TrFE), is a promising candidate due to its relatively high remnant polarization, low coercive field, fast switching times, easy processability, and low Curie transition. However, no detailed study of charge injection and current transport properties in P(VDF-TrFE) have been reported in the literature yet. Charge injection and transport are believed to affect various properties of ferroelectric films such as remnant polarization values and polarization fatigue behavior.. Thus, this thesis aims to study charge injection in P(VDF-TrFE) and its transport properties as a function of electrode material. Injection was studied for Al, Ag, Au and Pt electrodes. Higher work function metals such as Pt have shown less leakage current compared to lower work function metals such as Al for more than an order of magnitude. That implied n-type conduction behavior for P(VDF-TrFE), as well as electrons being the dominant injected carrier type. Charge transport was also studied as a function of temperature, and two major transport regimes were identified: 1) Thermionic emission over a Schottky barrier for low fields (E < 25 MV/m). 2) Space-Charge-Limited regime at higher fields (25 < E <120 MV/m). We have also studied the optical imprint phenomenon, the polarization fatigue resulting from a combination of broad band optical illumination and DC bias near the switching field. A setup was designed for the experiment, and validated by reproducing the reported effect in polycrystalline Pb(Zr,Ti)O3 , PZT, film. On the other hand, P(VDF-TrFE) film showed no polarization fatigue as a result of optical imprint test, which could be attributed to the large band gap of the material, and the low intensity of the UV portion of the arc lamp white light used for the experiment. Results suggest using high work function metals for a memory application, as lower leakage would enhance fatigue endurance for P(VDF-TrFE) film.en
dc.language.isoenen
dc.subjectTransport propertiesen
dc.subjectFerroelectric polymersen
dc.subjectP(VDF-TrFE)en
dc.subjectMemory applicationen
dc.subjectFatigueen
dc.titleTransport and Fatigue Properties of Ferroelectric Polymer P(VDF-TrFE) For Nonvolatile Memory Applicationsen
dc.typeThesisen
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
thesis.degree.grantorKing Abdullah University of Science and Technologyen_GB
dc.contributor.committeememberManchon, Aurelienen
dc.contributor.committeememberSchwingenschlögl, Udoen
thesis.degree.disciplineMaterials Science and Engineeringen
thesis.degree.nameMaster of Scienceen
dc.person.id113158en
All Items in KAUST are protected by copyright, with all rights reserved, unless otherwise indicated.