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Improving the Performance of III-Nitride Emitters by Nanostructure Fabrication and Surface Plasmon Coupling

Renwick, Paul (2013) Improving the Performance of III-Nitride Emitters by Nanostructure Fabrication and Surface Plasmon Coupling. PhD thesis, University of Sheffield.

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Abstract

III-Nitride based LEDs are quickly being adopted as the next generation in almost all lighting applications due to their potential ability to emit throughout the visible wavelength spectrum. Major challenges exist however which need to be overcome to further increase the adoption of GaN based LEDs, including low efficiency, especially in the green wavelength (and longer) emitting region, and efficiency droop, currently a major issue with GaN based LEDs. This thesis begins by discussing studies made on nanostructures, where improvements to internal quantum efficiency and light extraction efficiency of InGaN/GaN MQW structures are observed. An improvement in efficiency droop is also observed, linked to a reduction in LO-phonon coupling, and quantified by data fitting and the Huang-Rhys factor. Surface plasmon-quantum well interaction is discussed, where an optimised Ag film thickness and morphology is developed leading to an increase in PL emission of up to twenty five times for InGaN/GaN SQW structures, as well as a improvement in internal quantum efficiency. The combination of these two techniques is investigated, resulting in the development of single nanorod emitters showing significant enhancement of InGaN QW structures. Finally stimulated emission is observed by surface plasmon coupling enhanced InGaN QW based single nanorods, offering a potential fabrication technique to realise nano-laser technologies.

Item Type: Thesis (PhD)
Keywords: GaN, InGaN, Nanostructure, Surface Plasmon,
Academic Units: The University of Sheffield > Faculty of Engineering (Sheffield) > Electronic and Electrical Engineering (Sheffield)
Identification Number/EthosID: uk.bl.ethos.605211
Depositing User: Mr Paul Renwick
Date Deposited: 22 Apr 2014 10:21
Last Modified: 03 Oct 2016 11:16
URI: http://etheses.whiterose.ac.uk/id/eprint/5669

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