Evaluation of Pb0.95La0.05Zr0.54Ti0.46O3 thin film based capacitors for photovoltaic applications: using top electrodes of varying work function

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dc.contributor Li, Dawen
dc.contributor Burkett, Susan L.
dc.contributor Mewes, Claudia K. A.
dc.contributor Frazier, Rachel M.
dc.contributor.advisor Kotru, Sushma
dc.contributor.author Batra, Vaishali
dc.date.accessioned 2019-02-12T14:31:53Z
dc.date.available 2019-02-12T14:31:53Z
dc.date.issued 2018
dc.identifier.other u0015_0000001_0003243
dc.identifier.other Batra_alatus_0004D_13647
dc.identifier.uri http://ir.ua.edu/handle/123456789/5426
dc.description Electronic Thesis or Dissertation
dc.description.abstract Ferroelectricity and optical transparency are the two properties of lanthanum doped lead zirconate titanate (PLZT) that are utilized to explore its use for photovoltaic (PV) applications. A ferroelectric material sandwiched between two electrodes forms a MFM (metal/ferroelectric/metal) capacitor structure and can generate photocurrent and photovoltage under illumination. The PV effect in these structures is a combination of bulk PV effect and metal/ferroelectric interface effect. Both the material and the electrode properties are critical to improve the PV parameters obtained from these structures. A careful selection of electrode material can enhance the interface photovoltaic effect by modifying the Schottky barrier formed at the interface between electrode and ferroelectric material. This work investigates the effect of top electrodes of varying work functions on the photovoltaic properties of ferroelectric Pb0.95La0.05Zr0.54Ti0.46O3 (PLZT) thin films. PLZT thin films were prepared using a chemical solution deposition method and post annealed in the temperature range of 550-750 ˚C. A variety of characterization methods including x-ray diffraction, Raman, UV-visible and x-ray spectroscopy were used to understand the material properties of the grown films. A detailed analysis of ferroelectric measurements of the films was carried out to study their electrical behavior. Films annealed at annealing temperature (Ta) of 750 ˚C exhibit perovskite peaks, and higher chemical valence states and polarization compared to films annealed at lower temperatures. Thus, Ta of 750 ˚C was chosen to design capacitors studied in this work. Metal/PLZT/Pt (MFM) symmetric and asymmetric capacitor structures with various metals (Pt, Au, and Al) as top electrodes were fabricated. The asymmetric structure designed with Au top and Pt bottom electrode showed an improvement in the PV parameters, while retaining the ferroelectric properties. On the other hand, the symmetric structure designed with Pt top and bottom electrode showed lower PV parameters, but higher polarization. This work further investigated the ferroelectric and photovoltaic properties of PLZT thin film capacitors in two different electrode configurations, coplanar and interplanar, using Au electrodes. A simulation PV model was designed for the symmetric structure, which was helpful in understanding the charge transport properties. This work was extended to design a simulation model for asymmetric structure using ITO as top and Pt as bottom electrode. This work suggests that asymmetric structure results in higher charge transport, which results in higher PV parameters of PLZT thin film based capacitors.
dc.format.extent 244 p.
dc.format.medium electronic
dc.format.mimetype application/pdf
dc.language English
dc.language.iso en_US
dc.publisher University of Alabama Libraries
dc.relation.ispartof The University of Alabama Electronic Theses and Dissertations
dc.relation.ispartof The University of Alabama Libraries Digital Collections
dc.relation.hasversion born digital
dc.rights All rights reserved by the author unless otherwise indicated.
dc.subject.other Electrical engineering
dc.title Evaluation of Pb0.95La0.05Zr0.54Ti0.46O3 thin film based capacitors for photovoltaic applications: using top electrodes of varying work function
dc.type thesis
dc.type text
etdms.degree.department University of Alabama. Department of Electrical and Computer Engineering
etdms.degree.discipline Electrical and Computer Engineering
etdms.degree.grantor The University of Alabama
etdms.degree.level doctoral
etdms.degree.name Ph.D.

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