Date of Award

2021

Document Type

Doctoral Thesis

Degree Name

Doctor of Philosophy

Department

Physical Sciences

First Advisor

Dr. Tomasz J. Ochalski

Abstract

Perturbation of the inherent radiation equilibrium in solids by an external energy could engender an emission of the superfluous energy as electromagnetic radiation, or luminescence. Photoluminescence methods precipitate this disintegration of radiation equilibrium often by supplying the external energy as photons with energies higher than the bandgap energy of the solid. Since the excitation energy momentarily transforms the medium before luminescence is emitted, photoluminescence experiments are able to produce diverse and intricate spectroscopic data detailing the optical properties of the solid as a measure of this transformation. The pliability of allowed electron states in semiconductors have instigated bourgeoning research in the engineering of their bandgaps for a variety of applications. Owing primarily to its non-destructive nature and flexibility of bespoke experimental setups to meet specific constraints and objectives, photoluminescence spectroscopy is a universally adopted tool in the optical characterization of semiconductors. In this dissertation, electron and hole dynamics describing the luminescence properties of three types of novel semiconductor systems are derived with laser spectroscopy experimental techniques. This includes stacked layers of Type-II GaSb/GaAs quantum rings, InGaAsN:H quantum dots and AlGaAsSb quaternary alloys. The quantum ring ensemble exhibited long radiative recombination times and significant blue shifts of peak position energies with increasing excitation powers, in addition to demonstrating quantum coherence with Aharonov-Bohm oscillations. Time-resolved photoluminescence enabled identification of shallow and deep localization centres present in the quantum dots, formed as a result of hydrogen irradiation and dilute nitride incorporation in the host lattice. Finally, the substantial effects of Sb in the indirect bandgap quaternary alloy which dominate its optical characteristics have also been determined with photoluminescence experiments.

Comments

This dissertation was prepared in association with Tyndall National Institute.

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Access Level

info:eu-repo/semantics/openAccess

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