Domain switching and spatial dependence of permittivity in ferroelectric thin films

Persistent Link:
http://hdl.handle.net/10150/282219
Title:
Domain switching and spatial dependence of permittivity in ferroelectric thin films
Author:
Chai, Francis Kang-liang, 1968-
Issue Date:
1996
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
A domain model consistent with the measured capacitance-voltage ( CV) characteristic of PZT (Pb( Zr,Ti)O₃) capacitors is proposed. The model is introduced using a macroscopic electric field that is spatially uniform through the depth of the film. Then this multiple-domain model is generalized, and a spatially varying electric field model with a domain structure varying through the depth of the film is proposed. The spatial variation of the electric field is caused by dopant-ion charges in this work. A position-dependent permittivity is then deduced. Based upon this permittivity, the extraction of doping profiles in ferroelectric thin film capacitors using ferroelectric capacitance-voltage (CV) measurements is studied. The doping profile relation to measured CV curves for ferroelectric thin film capacitors is found to be analogous to the well-known result of metal-semiconductor Schottky junctions with an easily determined effective dielectric constant. Computer simulation shows the electrical doping concentration of ferroelectric thin film capacitors can be profiled accurately with the proposed model. The profiling shows compensation of the p-type PZT samples by the n-type niobium doping. Limitations of the Schottky profiling on ferroelectrics are investigated. Based on the approximate doping profiles extracted from CV measurement and the deduced permittivity, the measured CV characteristics are reconstructed through computer simulations. It is found that there is a minimum doping level below which it is not possible to obtain the doping profile from CV measurements. This minimum level depends on the shape of the CV curve, and a method to determine this minimum level from the CV curve is presented. For the films measured in this work, the minimum level is about 10¹⁸ cm⁻³. It is also found using the model that niobium doping slightly slows the volume growth of polarization with the electric field and has a tendency to increase the coercive field.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Engineering, Electronics and Electrical.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Electrical and Computer Engineering
Degree Grantor:
University of Arizona
Advisor:
Schrimpf, Ronald D.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleDomain switching and spatial dependence of permittivity in ferroelectric thin filmsen_US
dc.creatorChai, Francis Kang-liang, 1968-en_US
dc.contributor.authorChai, Francis Kang-liang, 1968-en_US
dc.date.issued1996en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractA domain model consistent with the measured capacitance-voltage ( CV) characteristic of PZT (Pb( Zr,Ti)O₃) capacitors is proposed. The model is introduced using a macroscopic electric field that is spatially uniform through the depth of the film. Then this multiple-domain model is generalized, and a spatially varying electric field model with a domain structure varying through the depth of the film is proposed. The spatial variation of the electric field is caused by dopant-ion charges in this work. A position-dependent permittivity is then deduced. Based upon this permittivity, the extraction of doping profiles in ferroelectric thin film capacitors using ferroelectric capacitance-voltage (CV) measurements is studied. The doping profile relation to measured CV curves for ferroelectric thin film capacitors is found to be analogous to the well-known result of metal-semiconductor Schottky junctions with an easily determined effective dielectric constant. Computer simulation shows the electrical doping concentration of ferroelectric thin film capacitors can be profiled accurately with the proposed model. The profiling shows compensation of the p-type PZT samples by the n-type niobium doping. Limitations of the Schottky profiling on ferroelectrics are investigated. Based on the approximate doping profiles extracted from CV measurement and the deduced permittivity, the measured CV characteristics are reconstructed through computer simulations. It is found that there is a minimum doping level below which it is not possible to obtain the doping profile from CV measurements. This minimum level depends on the shape of the CV curve, and a method to determine this minimum level from the CV curve is presented. For the films measured in this work, the minimum level is about 10¹⁸ cm⁻³. It is also found using the model that niobium doping slightly slows the volume growth of polarization with the electric field and has a tendency to increase the coercive field.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectEngineering, Electronics and Electrical.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineElectrical and Computer Engineeringen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorSchrimpf, Ronald D.en_US
dc.identifier.proquest9720598en_US
dc.identifier.bibrecord.b34528349en_US
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