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CC BY V4.0, Open Access
Dissertation
Ferroelectric Properties and Exciton Localization in Two-Dimensional Semiconductors
Washington State University
Doctor of Philosophy (PhD), Washington State University
01/2021
DOI:
https://doi.org/10.7273/000003136
Handle:
https://hdl.handle.net/2376/122526
Abstract
The ferroelectric and optical properties of two-dimensional indium selenide (In2Se3), as well as the mechanical and optical properties of stacked monolayer molybdenum di-selenide (MoSe2) and tungsten di-selenide (WSe2), were investigated through a variety of electrical and spectroscopic techniques. Of special interest was how domains are formed during the ferroelectric polarization flipping (generated with an applied voltage) within In2Se3 memristors. Notably, in the change between low and high resistance states, the polarization flipping was limited to the channel region between the biased and grounded electrodes, not at the electrode contact as previously assumed. The ferroelectric properties of In2Se3 were also examined in how they responded to low-level illumination by a laser. By exposing the layers to global and localized light illumination it was found that the light generated changes in the ferroelectric polarization. These changes were especially evident when polarization changes generated by electrical pulses were put under illumination. This resulted in movement of the ferroelectric domain regions as a direct effect of the low-level illumination without any voltage-generated electric field. Finally, MoSe2 and WSe2 heterobilayer structures were tested under extremely localized tip-enhanced photoluminescent (PL) measurements which revealed the presence of interlayer trions that responded to mechanical stress and small-scale surface inhomogeneities with significant shifts in their PL peaks. These observed features are much smaller than the diffraction limit of traditional PL mapping, providing new insight into exciton formation. These investigations into semiconductor properties reveal a variety of potential directions for semiconductor research going forward, especially ferroelectric domain wall motion and characterization of strain-tuned optical emission in heterostructures.
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Details
- Title
- Ferroelectric Properties and Exciton Localization in Two-Dimensional Semiconductors
- Creators
- Matthew Louis Gabel
- Contributors
- Yi Gu (Advisor)Matthew McCluskey (Committee Member)Brian Collins (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Physics and Astronomy, Department of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 118
- Identifiers
- 99900651900401842
- Language
- English
- Resource Type
- Dissertation