The van der Waals epitaxy of bismuth chalcogenide topological insulators for terahertz plasmonic applications
| Author(s) | Ginley, Theresa P. | |
| Date Accessioned | 2020-04-15T12:52:08Z | |
| Date Available | 2020-04-15T12:52:08Z | |
| Publication Date | 2019 | |
| SWORD Update | 2020-02-06T17:01:56Z | |
| Abstract | Bismuth chalcogenide topological insulators are of great interest to scientist due to their unique band structures. They are characterized by linear surface states that cross the bulk band gap. In these surface states, electrons are confined to two dimensions in a Dirac cone, much like electrons in graphene. It is these surface states electrons that make topological insulators so interesting, as electrons that inhabit them are massless, travel at relativistic speeds, and are spin polarized. Understanding these materials could help in fundamental physics applications, like the search for the Majorana fermion or the definition of the Ohm, to device-based applications, such as spin computing or improving sensors in hard to reach frequency ranges. ☐ The key to good material science research is the ability to produce high quality material. To that end this dissertation explored the growth of bismuth chalcogenide topological insulators. We sought to not only improve the quality of the material, but to understand the mechanism at work in van der Waals epitaxy. The growth of Bi2Se3with a selenium cracker cell on sapphire substrates was explored to reduced selenium vacancies and improve the electrical properties of the system. Results from initial research suggested that bulk behaviors did not dominate in thin films and instead a layer of disorder at the interface was to blame for the high bulk doping in thin films. Thus, a (Bi1-xInx)2Se3 buffer layer was used to bury the interface, resulting in reduced bulk carriers and improved mobilities. Attempts to recreate this buffer layer on GaAs(001) substrates resulted in complex 3D morphologies in the (Bi1-xInx)2Se3. We attribute these morphologies to the interaction of bismuth with the reconstructed surface of GaAs(011) after deoxidization, as well as the tendency of In2Se3 to phase segregate. Finally, the unique properties of topological insulators were explored by demonstrating the excitation of coupled two dimensional Dirac plasmons in patterned Bi2Se3 samples. This dissertation demonstrates improved knowledge of van der Waals epitaxy as well as contributing to the field of three-dimensional topological insulators. | en_US |
| Advisor | Law, Stephanie | |
| Degree | Ph.D. | |
| Department | University of Delaware, Department of Materials Science and Engineering | |
| DOI | https://doi.org/10.58088/1298-f631 | |
| Unique Identifier | 1150883585 | |
| URL | http://udspace.udel.edu/handle/19716/25783 | |
| Language | en | |
| Publisher | University of Delaware | en_US |
| URI | https://search.proquest.com/docview/2377938078?accountid=10457 | |
| Title | The van der Waals epitaxy of bismuth chalcogenide topological insulators for terahertz plasmonic applications | en_US |
| Type | Thesis | en_US |