Dissertation
Ferroelectric domain engineering in thin films and its applications
Doctor of Philosophy (Ph.D.), Drexel University
Aug 2017
DOI:
https://doi.org/10.17918/etd-7775
Abstract
Compared with dielectrics, ferroelectrics exhibit spontaneous polarization below the Curie temperature. Among them, ferroelectricity in perovskite ABO3 oxides generally relies on acentric B-site cation displacements. The spontaneous polarization has multiple energetically equivalent variants, the number of which depends principally on the structural phase and external symmetry-lowering fields. The omnidirectional feature is highly advantageous for non-volatile memory and piezoelectric transducer applications. Recently, ferroelectrics have garnered additional interest for use in photovoltaics, and as novel gate materials for adjacent conducting channels. In the thesis, we use phenomenological Ginzburg-Landau-Devonshire model incorporating temperature and strain to inform the design of single composition and compositionally-graded ferroelectric thin films. Following detailed thermodynamic calculations and analysis of the phase diagrams in candidate ferroelectrics, thin film growths are carried out by pulsed laser deposition, and film properties and domain structures are characterized using X-ray diffraction, atomic force microscopy and piezoelectric force microscopy at different temperatures, including dual-amplitude resonant tracking and band-excitation variants. Ferroelectric domain structures and polarization gradients not found in bulk enhance the figure of merit and achieve new functionalities in selected thin films, including those coupled with semiconductor channels, e.g., at or near the surface of a substrate. Through combination of simulation,film growth and characterizations, a general route of complex domain engineering in ferroelectric thin film and their applications are realized.
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Details
- Title
- Ferroelectric domain engineering in thin films and its applications
- Creators
- Zongquan Gu - DU
- Contributors
- Jonathan E. Spanier (Advisor) - Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- xiii, 102 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- College of Engineering (1970-2026); Electrical (and Computer) Engineering (1970-2026); Drexel University
- Other Identifier
- 7775; 991014632181404721