Experimental Interrogation Of One-Dimensional Excitons In Cadmium Selenide And Cadmium Telluride Quantum Nanostructures

<p>The lengths of one-dimensional quantum wires: QWs) make them excellent candidates for implementation into devices that require charge transport over micrometer-scale distances. Additionally, their tunable band-gap energies, polarized emission, and large absorption cross sections make them quite attractive for potential use in photovoltaic and optoelectronic devices. The quantum-confined radial dimension of quantum wires increases the coulombic interaction between photo-generated excitons, and therefore increase the exciton binding energy as compared to bulk and quantum well structures. In this thesis, excitons in single one-dimensional CdSe and CdTe QWs were investigated using a combination of optical microscopy techniques. My work indicates that excitons in single quantum wires are bound at room temperature, and can behave as quantum mechanical 1-D particles. Emission is observed from bound excitons levels within the first electronic state, and a binding energy between 57-64 meV is reported. By modifying the potential energy landscape of a wire using photo-generated excitons to fill trap sites, I show that excitons can delocalize along the length of an entire QW, with distances spanning up to 10 microns. Low temperature studies indicate that the potential energy landscape is not uniform along the length of a CdTe wire, and fluctuations in the potential are likely due to a combination of variations in the crystal structure and surface irregularities. Additionally, I show that because of their polarized emission, exciton delocalization, and tunable band-gap energies, excitons in highly efficient CdSe quantum belts can also behave as 1-D quantum mechanical particles.</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Chemistry

Year dc:date.available

2012

Author dc:creator

• Wayman, Virginia Lorraine

Contributors dc:contributor

• Richard A Loomis

• CdSe
• excitons
• microscopy
• nano
• quantum wires
• spectroscopy

Language dc:language

English (en)

DOI

https://doi.org/10.7936/K7XW4GTN

OAI identifier oai:identifier

oai:openscholarship.wustl.edu:etd-1988