Electrical and Computer Engineering ETDs

Publication Date

9-12-2014

Abstract

Quantum dots, due to their small size, portray unique optical properties that are different compared to those of the bulk material. The most apparent of these properties is the excitation of these dots, resulting in emission of photons, which are visible to the human eye as light. More interestingly, the wavelength of these photon emissions does not solely depend on the type of material from which the quantum dot is made; in addition, it depends on the size of the quantum dots. The dots can also be tuned accordingly to emit into the UV or into the infra-red. The colloidal synthesis of CdSe/ZnS quantum dots is presented, to describe their incorporation into nanovoids formed on GaSb membranes. Nanoscale etch-pit formation on GaSb surfaces happens as a result of arsenic (As2) based in situ etch technique. The effect of in situ etch technique leading to the formation of the nanovoids was studied. Atomic force microscopy, scanning electron microscope, and transmission electron microscopy were used to characterize the GaSb surface, to investigate the internal structure of the voids, and to determine the average size dimensions of the voids, and the void density. Furthermore, experiments and measurements were carried out to check the ability of the quantum dots to fluoresce at the high regrowth temperatures inside the molecular beam epitaxy system. CdSe/ZnS quantum dots were used, considering their high stability over time. The quantum dots were further annealed at different temperatures, and optically characterized to investigate if the core-shell structure changed as a result of the high temperature. Encapsulation of these quantum dots into the highly faceted nanovoids offer potential applications for quantum-confined ensembles.

Keywords

quantum dots, colloidal synthesis, nanovoids, GaSb

Sponsors

Air Force Research Laboratory (AFRL)

Document Type

Thesis

Language

English

Degree Name

Electrical Engineering

Level of Degree

Masters

Department Name

Electrical and Computer Engineering

First Committee Member (Chair)

Rotter, Thomas

Second Committee Member

Rishinaramangalam, Ashwin K.

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