Ultrafast photovoltaic responses in ferroelectric thin films
Abstract/Contents
- Abstract
- The interaction of ultrashort light pulses with the medium of the ferroelectric is a fundamental question for photonics and photovoltaic applications. I report two advances toward our understanding of this family of materials in the ultrafast regime: (1) Using femtosecond time-resolved x-ray scattering to observe changes in the unit-cell tetragonality of thin films of the prototypical ferroelectric lead titanate, PbTiO3, we show the direction, magnitude and physical mechanisms underlying the photocurrents generated by femtosecond near-bandgap photoexcitation. These findings elucidate the ultrafast photovoltaic response in these ma- terials, illustrate the intrinsic coupling between their electronic and structural degrees of freedom, and show that light can enhance the functional properties of ferroelectrics on nanosecond timescales. In addition, we observe that femtosecond optical pulses can reversibly switch the ferroelectric phase to the non-polar paraelectric phase. (2) In order to further investigate mechanisms for using light to manipulate the ferroelectric polarization, a terahertz (THz) pulse source based on coherent transition radiation has been commissioned, which generates single-cycle pulses lasting roughly 100 fs with peak fields greater than 20 MV/cm and energies in excess of 100 uJ. These pulses contain frequencies resonant with the "soft mode" reaction coordinate of the ferroelectric-paraelectric phase transition, and their high peak fields drive strong nonlinear optical responses in materials. As a first demonstration, I show that this source drives an all-THz response in a silicon photodiode. Recent work shows that such pulses should permit purely optical steering of the ferroelectric polarization.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2012 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Daranciang, David Dan Ramelb |
|---|---|
| Associated with | Stanford University, Department of Chemistry |
| Primary advisor | Lindenberg, Aaron Michael |
| Thesis advisor | Lindenberg, Aaron Michael |
| Thesis advisor | Chidsey, Christopher E. D. (Christopher Elisha Dunn) |
| Thesis advisor | Reis, David A, 1970- |
| Advisor | Chidsey, Christopher E. D. (Christopher Elisha Dunn) |
| Advisor | Reis, David A, 1970- |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | David Dan Ramelb Daranciang. |
|---|---|
| Note | Submitted to the Department of Chemistry. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2012. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2012 by David Dan Ramelb Daranciang
- License
- This work is licensed under a Creative Commons Attribution Non Commercial No Derivatives 3.0 Unported license (CC BY-NC-ND).
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