Author ORCID Identifier

https://orcid.org0000-0001-8801-4850

Date of Award

5-1-2019

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Physics and Astronomy

First Advisor

Vadym Apalkov

Second Advisor

Gennady Cymbalyuk

Abstract

The properties of a step-like defect on the surface of ultrathin topological insulator nanofilm have been studied. The reflectance of an electron from such a defect for different parameters of the nanofilm and the different parameters of the defect has been calculated. An electron incident on a steplike defect not only produces reflected and transmitted waves but also generates the modes, which are localized at the steplike defect. Such modes result in an enhancement of electron density at the defect by ≈ 60%. The magnitude of the enhancement depends on the parameters of the nanofilm and the height of the step and is the largest in the case of total electron reflection. Next, the quantum dots in 2D materials such as topological insulator nanofilm, germanene, and phosphorene were introduced. Intopologicalinsulator, We introduce a quantum dot as a bump at a surface of nanofilm. Such quantum dot can localize an electron if the size of the dot is large enough, ∼ 5 nm. The other type of quantum dot is created in germanene. The band gap of buckled graphene-like materials such as germanene, depends on the external electric field. Then a specially design profile of the electric field can produce trapping potential for electrons. Another type of quantum dot can be designed using phosphorene. Phosphorene itself has a band gap. By considering the piece of cylindrical phosphorene layer, an electron can be confined. We study the energy spectra of such defined quantum dots. The intraband and interband optical transitions within the dots have also been studied. The effects of the temperature and the substrate modify the model parameters and should not change the results considerably.

DOI

https://doi.org/10.57709/13607847

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