Physical Sciences and Mathematics Commons^™

Tuning Topological Surface States By Charge Transfer, Zhiyi Chen

Dissertations, Theses, and Capstone Projects

Three-dimensional (3D) topological insulators (TIs), Bi₂Se₃, Bi₂Te₃, Sb₂Te₃, are a class of materials that has non-trivial bulk band structure and metallic surface states. Access to charge transport through Dirac surface states in TIs can be challenging due to their intermixing with bulk states or non-topological two-dimensional electron gas quantum well states caused by bending of electronic bands near the surface. The band bending arises via charge transfer from surface adatoms or interfaces and, therefore, the choice of layers abutting topological surfaces is critical. Surfaces of these 3D TIs …

Classical Transport In Disordered Systems, Antonios Papaioannou

Dissertations, Theses, and Capstone Projects

This thesis reports on the manifestation of structural disorder on molecular transport and it consists of two parts. Part I discusses the relations between classical transport and the underlying structural complexity of the system. Both types of molecular diffusion, namely Gaussian and non-Gaussian are presented and the relevant time regimes are discussed. In addition the concept of structural universality is introduced and connected with the diffusion metrics. One of the most robust techniques for measuring molecular mean square displacements is magnetic resonance. This method requires encoding and subsequently reading out after an experimentally controlled time, a phase ϕ to the …

Properties Of Type-Ii Znte/Znse Submonolayer Quantum Dots Studied Via Excitonic Aharonov-Bohm Effect And Polarized Optical Spectroscopy, Haojie Ji

Dissertations, Theses, and Capstone Projects

In this thesis I develop understanding of the fundamental physical and material properties of type-II ZnTe/ZnSe submonolayer quantum dots (QDs), grown via combination of molecular beam epitaxy (MBE) and migration enhanced epitaxy (MEE). I use magneto-photoluminescence, including excitonic Aharonov-Bohm (AB) effect and polarized optical spectroscopy as the primary tools in this work.

I present previous studies as well as the background of optical and magneto-optical processes in semiconductor nanostructures and introduce the experimental methods in Chapters 1 - 3.

In Chapter 4 I focus on the excitonic AB effect in the type-II QDs. I develop a lateral tightly-bound exciton model …

Ultrafast Spectroscopy And Energy Transfer In An Organic/Inorganic Composite Of Zinc Oxide And Graphite Oxide, Jeff A. Secor

Dissertations, Theses, and Capstone Projects

The energy transfers and nature of defect levels of an organic/inorganic composite of Zinc Oxide and Graphite are studied with multidimensional spectroscopy. The edge and surface states of each composite are uncovered using excitation emission experiments showing which defect states are mediating the energy transfer from the metal oxide to the graphite oxide. Multidimensional time resolved spectroscopy further describes the effect of the carbon phase on the energy transfer pathways in the material.